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EPA Releases Case Study on California’s San Pedro Bay Ports Addressing Air Quality and Environmental Justice in Nearby Communities

April 1, 2021

WASHINGTON (April 1, 2021) — Today, the U.S. Environmental Protection Agency (EPA) released a new case study on the San Pedro Bay Ports’ Clean Air Action Plan (CAAP), which was the first U.S. port air quality program to include air emission reduction targets. The CAAP is a groundbreaking and ongoing program at the Port of Los Angeles and the Port of Long Beach, collectively known as the San Pedro Bay Ports. The program is a result of action by community members, and coordination between port operators as well as state and local agencies among others, in addressing air quality impacts from port operations. This collaboration paved the way for significantly cleaner air for near-port communities with environmental justice concerns and can serve as model for port stakeholders nationwide.

“The Clean Air Action Plan is an excellent example of what can happen when port operators work with neighboring communities to develop and implement a robust plan, leading to positive impacts on air quality and emissions,” said EPA Administrator Michael S. Regan. “While there is still lots of work to be done in San Pedro Bay, this trailblazing effort can serve as a model for the rest of country to follow.”

The case study originated from conversations with EPA, the Moving Forward Network and near-port community stakeholders, and was developed as part of the EPA Ports Initiative. The case study presents best practices and lessons learned that other port authorities and near-port communities may find useful when implementing air quality actions including the importance of:

• Collaborating among ports and communities; • Conducting emission inventories; • Setting quantified emissions targets; • Supporting technical innovations; and • Developing partnerships with industry and government.

The case study summarizes the CAAP’s background and history, and includes three discussions on environmental justice and levers of community influence; technologies and practices for development and deployment; and an overview of the San Pedro Bay Ports' 2017 Clean Truck Program. The accompanying fact sheets highlight key overarching conclusions as well as takeaways from the three focused discussions.

Ports are critical for commerce, a keystone for economic growth, and play a significant role in the goods movement supply chain. Investing in clean port infrastructure and operations supports economic prosperity and reductions in emissions.  EPA’s Ports Initiative works to improve efficiency and reduce harmful air pollution at ports by advancing next-generation, clean technologies and practices, and collaboration among stakeholders including the port industry, communities, and all levels of government.

To review the CAAP case study, please visit: https://www.epa.gov/ports-initiative/san-pedro-bay-ports-clean-air-action-plan-best-practices-and-lessons-learned

EPA’s Ports Initiative has a number of resources to support port operators and community groups to take steps to address diesel pollution and improve air quality. To learn more about EPA’s Ports Initiative, please visit: https://www.epa.gov/ports-initiative

For information on Environmental Justice Small Grants (EJSG) to support communities living near port and rail facilities to address diesel pollution (applications due May 7), please visit: https://www.epa.gov/community-port-collaboration/2021-environmental-justice-small-grants-opportunity-communities-living  

For information on EPA resources to support community-port collaboration, including an upcoming webinar on April 9, please visit: https://www.epa.gov/community-port-collaboration

Suggested citation: Khan, Adeel, Uday Suryanarayanan, Tanushree Ganguly, and Karthik Ganesan. Improving Air Quality Management through Forecasts: A Case Study of Delhi’s Air Pollution of Winter 2021. New Delhi: Council on Energy, Environment and Water.

This study assesses Delhi’s air pollution scenario in the winter of 2021 and the actions to tackle it. Winter 2021 was unlike previous winters as the control measures mandated by the Commission of Air Quality Management (CAQM) in Delhi National Capital Region and adjoining areas were rolled out. These measures included the Graded Response Action Plan (GRAP) and additional emergency responses instituted on the basis of air quality and meteorological forecasts. Given that the forecasts play a major role in emergency response measures, the study assesses the reliability of different forecasts. Further, it gauges the impact of the emergency measures on Delhi’s air quality levels. It also discusses the primary driver of air pollution in winter 2021.

Key Findings

• While air quality forecasts picked up the pollution trends, they are not yet very accurate in predicting high pollution episodes ('very poor' and 'severe' air quality days)
• When the restrictions were in place like ban on entry of trucks, construction & demolition activities and others, air quality did not descend into the ‘severe +’ category. Moreover, air quality improved from ‘severe’ to ‘poor’ when all the restrictions were in place simultaneously, aided by better meteorology.
• However, when the restrictions were finally lifted, the air quality spiralled back into the ‘severe’ category resulting in the longest six days ‘severe’ air quality spell of the season.
• There has been no significant improvement in Delhi's winter air quality since 2019. In winter 2021, air quality was in the ‘very poor’ to ‘severe’ category on about 75 per cent of days.
• In the winter of 2021, transport(∼ 12 per cent), dust (∼ 7 per cent) and domestic biomass burning (∼ 6 per cent) were the largest local contributors.
• About 64 per cent of Delhi’s winter pollution load comes from outside of Delhi’s boundaries.

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Executive Summary

With every passing winter, the need to address Delhi’s air pollution grows more urgent. During the winter of 2021, the Supreme Court, the Delhi Government, and the Commission for Air Quality Management in the NCR and Adjoining Areas (CAQM), all sprang into action to arrest rising pollution levels in Delhi. The interventions ranged from shutting down power plants and restricting the entry of trucks into Delhi to school closures and using forecasts to pre-emptively roll out emergency measures. However, the impact of these interventions on Delhi’s air quality begs further investigation.

Through this study, we intend to examine what worked and what did not this season. As is the case every year, meteorological conditions played an important role in both aggravating and alleviating pollution levels. To assess the impact of meteorological conditions on pollution levels, we analysed pollution levels during the months of October to January vis-a-vis meteorological parameters. To understand the driving causes of pollution in the winter of 2021, we tracked the changes in relative contribution of various polluting sources as the season progressed.

While pre-emptive actions based on forecasts was a step in the right direction, an assessment of forecast performance is a prerequisite to integrating them in decision-making. We also assessed the performance of forecasts by comparing them with the measured onground concentrations. We also studied the timing and effectiveness of emergency directions issued in response to forecasts.

We sourced data on pollution levels from Central Pollution Control Board’s (CPCB) real-time air quality data portal and meteorological information from ECMWF Reanalysis v5 (ERA5). For information on modelled concentration and source contributions, we used data from publicly available air quality forecasts, including Delhi’s Air Quality Early Warning System (AQ-EWS) (3-day and 10-day), the Decision Support System for Air Quality Management in Delhi (DSS), and UrbanEmissions.Info (UE).

Figure ES1 In Delhi, 75% of Winter 2021 saw 'very poor' to 'severe' air quality

Source: Authors’ analysis, data from Central Pollution Control Board (CPCB). Note: Air quality index (AQI) for the day is calculated using the PM2.5 concentration at the same stations with a minimum of 75 per cent of the data being available.

A. 75 per cent of days were in ‘Very poor’ to ‘Severe’ air quality during winter 2021

The number of ‘Severe’ plus ‘Very poor’ air quality days during the winter has not decreased in the last three years (Figure ES1). During the winter of 2021 (15 October 2021 - 15 January 2022), about 75 per cent of the days, air quality were in the ‘Very poor’ to ‘Severe’ category. Interestingly, despite more farm fire incidents in Punjab, Haryana, and Uttar Pradesh in 2021 compared to 2020, Delhi’s PM2.5 concentration during the stubble burning phase (i.e., 15 October to 15 November) was lesser in 2021. This was primarily due to better meteorological conditions like higher wind speed and more number of rainy days during this period.

B. Regional influence predominant; Transport, dust, and domestic biomass burning are the largest local contributors to air pollution

We find that about 64 per cent of Delhi’s winter pollution load comes from outside Delhi’s boundaries (Figure ES2(a). Biomass burning of agricultural waste during the stubble burning phase and burning for heating and cooking needs during peak winter are estimated to be the major sources of air pollution from outside the city according to UE (Figure ES2(b). Locally, transport (12 per cent), dust (7 per cent), and domestic biomass burning (6 per cent) contribute the most to the PM2.5 pollution load of the city. While transport and dust are perennial sources of pollution in the city, the residential space heating component is a seasonal source. However, this seasonal contribution is so significant that as the use of biomass as a heat source in and around Delhi starts going up as winter progresses, the residential sector becomes the single-largest contributor by 15 December (Figure ES2(b)). This indicates the need to ramp up programmes to encourage households to shift to cleaner fuels for cooking and space heating.

Figure ES 2(a) Transport, dust, and domestic biomass burning are the largest local contributors to the PM2.5 pollution load in Delhi

Source: Authors’ analysis, source contribution data from DSS and UE. Note: Modelled estimates of relative source contributions retrieved from UE and DSS.

Figure ES 2(b) Both local and regional sources need to be targeted for reducing Delhi’s pollution

Source: Authors’ analysis, source contribution data from UE. Note: Source contribution data retrieved from UE district products which have larger geographical cover and lower resolution.

C. Forecasts picked up the pollution trend but could not predict high pollution episodes

The availability of multiple forecasts provides decisionmakers with a range of options to choose from. At the same time, this is an obstacle to effective onground action. To streamline the flow of relevant information from forecasters to decision-makers, it is important to analyse the forecasts and assess their reliability. We found that all the forecasts identified pollution trends accurately (Figure ES3) but their accuracy in predicting pollution episodes (‘Severe’ and ‘Very Poor’ air quality days) decreases with future time horizon.

D. Though forecasts were used to impose restrictions, the lifting of the curbs was ill-timed

In November–December 2021, apart from the Graded Response Action Plan (GRAP) coming into effect in DelhiNCR, the CAQM introduced several emergency response measures through a series of directions and orders. The Supreme Court also stepped in from time to time to direct the authorities to act on air pollution.

As a first, the CAQM used air quality and meteorological forecasts to time and tailor emergency response actions. The first set of restrictions was put in place on 16 November 2021, and all were lifted by 20 December 2021, save the one on industrial operations.

Figure ES3 All the forecasts can predict the trend accurately

Source: Authors’ analysis, data from Central Pollution Control Board (CPCB), AQ-EWS, and UE. Note: r represents correlation.

During this period, all the forecasts except AQ-EWS (3-day) underpredicted PM2.5 levels. Therefore, by looking at the difference between forecasted and measured concentrations, it is not possible to gauge the effectiveness of the restrictions conclusively. Hence, multiple models or different modelling experiments are needed to estimate the impact of the intervention.

It should be noted that during the restriction period, air quality did not descend into the ‘Severe +’ category. Further, when all the restrictions were in place along with better meteorology, air quality did improve from ‘Severe’ to ‘Poor’. The first prolonged ‘Severe’ air quality period in December was witnessed between 21 December and 26 December. While the forecasts sounded an alarm for high pollution levels during this period, all restrictions barring those on industrial activities were lifted. Subsequently, PM2.5 levels remained above 250 µgm -3 for six straight days resulting in the longest ‘Severe’ air quality spell of the season. (Figure ES4).

Figure ES4 The lifting of the restrictions was ill-timed with high pollution levels forecasted in the following days

Source: Authors’ analysis, data from Central Pollution Control Board (CPCB). Note: C&D stands for construction and demolition activities. Work from home (WFH) stands for the 50% cap on employee attendance in the office. Industrial restrictions stand for compulsory switching over to Piped Natural Gas (PNG) or other cleaner fuels within industries and non-compliant industries being allowed to operate restrictively.

The discussion above highlights that despite the emergency measures taken in winter 2021, the air quality conditions were far from satisfactory. Calibrating emergency responses to forecasted source contributions may result in a greater impact on air quality. Our study recommends the following to help the Government of National Capital Territory of Delhi ( GNCTD) and CAQM plan and execute emergency responses better:

• GRAP implementation must be based strictly on modelled source contributions obtained from forecasts and timed accordingly. This will eliminate the need for ad-hoc emergency directions to restrict various activities. For instance, restrictions on private vehicles can be brought in when the air quality is forecasted to be ‘Very poor’ as transport is a significant contributor.
• Surveys or assessments are required in the residential areas across NCR to explore the prevalence of biomass usage for heating and cooking purposes. Based on this, a targeted support mechanism is required to allow households and others to use clean fuels for cooking and heating. There is also a need to assess and promote alternatives for space heating.
• Air quality forecasts should be relayed to the public via social media platforms to encourage them to take preventive measures such as avoiding unnecessary travel and wearing masks when stepping out. This will help reduce individual exposure and activity levels in the city.
• Ground level data and insights need to be incorporated in forecasting models. Data from sources like social media posts (text and photos), camera feeds from public places, and pollution related grievance portals like SAMEER, Green Delhi, and SDMC 311 can provide near-real time information on pollution sources. Then aggregated representation of polluting activities based on recent days or weeks can be used as an input in models. Ultimately, a crowd-sourced emissions inventory for NCT/NCR will benefit modellers and policymakers alike while also making pollution curtailment efforts transparent.
• Combining the available air quality forecasts through an ensemble approach can help improve the accuracy of the forecasts and prompt better coordination within the modelling community.

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Climate Change, Air Pollution, and Health Inequality: Vulnerability of Marginalized Populations

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Air pollution and climate change are two interconnected global challenges that have significant implications for public health. Marginalised populations, including low-income communities, minority groups, and indigenous peoples, often bear the brunt of these environmental hazards, facing disproportionate health impacts due to their heightened vulnerability. Factors such as limited access to healthcare, inadequate infrastructure, and socioeconomic disparities exacerbate their susceptibility to the adverse effects of pollution and climate variability. Despite growing awareness and efforts to address these issues, there remains a critical gap in understanding the specific mechanisms through which climate change and air pollution increase health inequalities among marginalised populations. This Research Topic aims to explore the complex interplay between climate change, air pollution, and health inequality, with a focus on understanding the vulnerabilities of marginalized populations. We seek to elucidate the underlying factors contributing to these disparities and identify strategies for mitigation and adaptation. Recent advances in interdisciplinary research have shed light on the differential impacts of environmental stressors on vulnerable communities, providing valuable insights into potential interventions. By bringing together researchers from diverse disciplines, we aim to foster collaboration and generate evidence-based solutions to address health inequalities in the face of climate change and air pollution, ultimately working towards a more equitable and sustainable future. We welcome contributions that examine various aspects of the vulnerability of marginalized populations to the intersection of climate change, air pollution, and health inequality. Specific themes of interest include but are not limited to: · Socioeconomic determinants of vulnerability · Health impacts and disparities · Environmental justice and equity · Community-based interventions and resilience-building · Climate change adaptation strategies for vulnerable populations · Cross-cultural perspectives on environmental health disparities · Case studies on successful implementation of environmental policies · Policy analysis and recommendations Manuscripts employing interdisciplinary approaches and providing innovative solutions are particularly encouraged. Join us in addressing this pressing global challenge and advancing knowledge for the benefit of all communities.

Keywords : Environmental Justice, Socioeconomic Disparities, Climate Vulnerability, Marginalized Communities

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Environmental Pollution and Public Health

Case studies on air, water and soil from an interdisciplinary perspective.

• 1st Edition - January 15, 2024
• Editors: Ronnie Frazer-Williams, Mary B. Ogundiran, Emmanuel I Unuabonah
• Language: English
• Paperback ISBN: 9780323959674 9 7 8 - 0 - 3 2 3 - 9 5 9 6 7 - 4
• eBook ISBN: 9780323959681 9 7 8 - 0 - 3 2 3 - 9 5 9 6 8 - 1

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Environmental Pollution and Public Health: Case Studies on Air, Water and Soil from an Interdisciplinary Perspective provides detailed case studies showing real-world applications of the latest technologies surrounding pollution in air, water and soil. Sections cover the environment and its nexus with public health, highlighting how the health of our environment can invariably influence our public health. Following this, atmospheric pollution is addressed, identifying various air pollutants, methods for identification, impacts on the environment and health, and mitigating technologies. Final sections are dedicated to liquid waste management, focusing on wastewater and treatment options including emerging technologies that are compared to existing options.

The book finishes with case studies and information on regulatory frameworks for environmental pollution for those wanting to implement the remediation techniques covered. This is a necessary read for postgraduates, academics, professionals and researchers in environmental science, soil science, environmental health, and waste management who need the latest sustainable remediation practices and case studies and the efficacy of the associated techniques.

• Offers a broad overview of the environmental and practical aspects of pollution, pollution control measures, and environmental impact assessment
• Focuses on providing detailed, global case studies with an emphasis on cost, efficiency and sustainability of the techniques for treating wastewater, contaminated soils and solid waste
• Provides theoretical and technical information that will assist professionals and practitioners in their goals to address current challenges stemming from environmental pollution
• Cover image
• Contributors
• Editors’ biography
• Part 1 The environment and its critical nexus with public health
• Chapter 1 Bacterial and viral contaminants in drinking water: Why do they really matter to us
• 1.1 Introduction
• 1.2 Microorganisms associated with water
• Chapter 2 The health of our environment and Sustainable Development Goal 3
• 2.1 Introduction
• 2.2 The environment and total well-being
• 2.3 The nature of our environment
• 2.4 Environmental health challenges
• 2.5 Perspectives
• 2.6 Conclusion
• Part 2 Atmospheric pollution and control
• Chapter 3 Air pollution: Prevention and control strategies
• 3.1 Introduction
• 3.2 Factors to consider in designing air pollution control strategy
• 3.3 Prevention and control strategies
• Part 3 Liquid waste management strategies
• Chapter 4 Low-cost and efficient technologies for the treatment of industrial wastewater
• 4.1 Introduction
• 4.2 Characteristics of industrial effluents
• 4.3 Low-cost technologies for industrial wastewater treatment
• 4.4 Conclusion
• Chapter 5 Treatment of landfill leachate
• 5.1 Introduction
• 5.2 Classification and characteristics of landfill leachate
• 5.3 Basic physical–chemical processes for landfill leachate treatment
• 5.4 Advanced oxidation processes for landfill leachate treatment
• 5.5 Biological processes for landfill leachate treatment
• 5.6 Recovering resources from landfill leachate
• 5.7 Typical combined landfill leachate treatment processes in application
• 5.8 Conclusion and perspectives
• Chapter 6 Wastewater circular economy
• 6.1 Introduction
• 6.2 Resource recovery
• 6.3 Wastewater reuses
• 6.4 Wastewater circular economy case studies
• 6.5 Conclusion and perspectives
• Part 4 Soil pollution and efficient municipal solid waste sorting and management practices
• Chapter 7 Soil pollution and management practices
• 7.1 Introduction
• 7.2 The impacts of soil pollution on the food chain and ecosystem services
• 7.3 Integrated soil management options for polluted soils
• Chapter 8 Technologies for resource recovery and recycling of solid wastes: A case study of recent advances and applications of municipal solid waste in Mauritius
• 8.1 Introduction
• 8.2 Waste generation rate, sources, and composition
• 8.3 Municipal solid waste management techniques in Mauritius
• 8.4 Landfill
• 8.5 Municipal solid waste recycling and composting
• 8.6 Waste sorting at the source and its benefits
• 8.7 Municipal solid waste resource and energy recovery
• 8.8 Strategies for overcoming barriers
• 8.9 Attitudes of the people towards municipal solid waste management
• 8.10 Future works and perspectives
• 8.11 Conclusion
• Acknowledgment
• Chapter 9 Soil contamination resulting from inefficient solid waste management
• 9.1 Introduction
• 9.2 Early practices of solid waste collection and disposal
• 9.3 Waste generation
• 9.4 Contribution of inappropriate solid waste collection and transportation system to soil contamination
• 9.5 Transfer stations
• 9.6 Dumpsites as a major contributor to soil contaminated with heavy metals
• 9.7 Contaminants in the soil as a result of poor solid waste management
• 9.8 Organic contaminants in dumpsite soils and environs
• 9.9 Conclusion
• Chapter 10 Sustainable remediation techniques for solid waste polluted soils
• 10.1 Introduction
• 10.2 Case studies of solid wastes as point sources of soil pollution
• 10.3 Health implications of polluted soils
• 10.4 Case studies of remediation techniques for heavy metal-polluted soils
• 10.5 Soil remediation with biochar
• 10.6 Soil remediation with compost
• Chapter 11 Soil pollution and climate change
• 11.1 Introduction
• 11.2 Soil pollution
• 11.3 Types of soil pollution
• 11.4 Major causes of soil pollution
• 11.5 Climate change
• 11.6 Soil pollution and climate change
• 11.7 Effects of climate change on soil pollution
• 11.8 Conclusion
• Part 5 Environmental justice, policies and regulatory frameworks
• Chapter 12 Environmental laws and enforcement: Prospects and challenges
• 12.1 Introduction
• 12.2 Conceptualizing “regulation” in environmental protection and enforcement
• 12.3 Global environmental protection and air pollution
• 12.4 Global environmental protection and soil pollution
• 12.5 Global environmental protection and water pollution
• 12.6 Conclusion
• Chapter 13 Environmental accounting for a quality regulatory framework
• 13.1 Introduction
• 13.2 Methodology
• 13.3 Findings, conclusion, and recommendation
• No. of pages : 400
• Language : English
• Edition : 1
• Published : January 15, 2024
• Imprint : Elsevier
• Paperback ISBN : 9780323959674
• eBook ISBN : 9780323959681

Ronnie Frazer-Williams

Ronnie A. D. Frazer-Williams is a Professor of Environmental and Analytical Chemistry at the University of Sierra Leone. He holds a BSc with honours in Chemistry (University of Sierra Leone), M. Eng. & M.Sc. in Environmental Science and Technology (IHE, Delft, The Netherlands) and PhD in Environmental Technology (Cranfield University, UK). Currently, he is the Dean of Postgraduate Studies, University of Sierra Leone. He has authored several articles both in peer review journals and conference proceedings and serves as a member of editorial teams of peer review journals. Ronnie has served as African representative to SAICM Ad Hoc Advisory Group of Chemical Expert; UNEP National Expert on Chemical Weapons Convention to the National Authority; External Examiners to universities; national consultant to the Environmental Protection Agency Sierra Leone on the National Implementation Plan under the Stockholm Convention and many others. Ronnie is a member of several international scientific and professional organizations notably Vice President of the West African Society of Toxicology and Vice President of West African Anglophone Quality Assurance Network.

Mary B. Ogundiran

Mary. B. Ogundiran is a Professor of Analytical/Environmental Chemistry at the Department of Chemistry, University of Ibadan, Nigeria.

She obtained B.Ed. Chemistry/Physics in 1994, M.Sc. Analytical Chemistry in 1997 and Ph.D. Analytical/Environmental Chemistry in 2007 from the University of Ibadan, Nigeria.

She was a Women for Africa Foundation Fellowship Researcher at Material Physics center (CFM) CSIC-UPV/EHU), San Sebastian, Spain, CV Raman International Fellowship Visiting Researcher to NML-CSIR Jamshedpur, India, and TWAS-DFG Visiting Scientist to Justus Liebig University Giessen, Germany. She did OPCW Postdoctoral Fellowship at the Department of Chemical Engineering, Delft University of Technology, the Netherlands.

She has supervised many undergraduate and postgraduate students and currently supervising research students. She has functioned in various administrative posts in her University.

She has authored many articles in peer review journals, conference proceedings, chapters in books and serves as a reviewer for many journals. Currently, she’s is the Vice president for Biochar Initiative of Nigeria (BIN) and member of the Editorial Board of BIN Journal.

Emmanuel I Unuabonah

Emmanuel I. Unuabonah is a Professor of Chemistry in the Department of Chemical Sciences, Redeemer’s University, Nigeria. His research work is focused on the development of relatively cheap functional materials for treatment of water and wastewater. He is currently developing photocatalytic materials from low-cost sources for water treatment. He has published several articles in international peer-reviewed Journals and has two national patents. He has won several research grants including the Cambridge-Africa ALBORADA, the Academy of Medical Sciences Global Challenges Research Fund Networking Grant Scheme (GCRF), TWAS-IsDB research grant for collaboration etc. He is also a recipient of several national and international awards and research fellowships including the TWASROSSA Young Scientist Award, SCOPE–Zhongyu Young Scientist Environmental Award (Environmental Technological Innovations category), African Union-TWAS Young Scientist Award in Basic Sciences, Technology and Innovation, the Alexander von Humboldt (AvH) Postdoctoral Research Fellowship, and the first Nigerian Academy of Science Gold Medal Prize. He is the Founding President of the Nigerian Young Academy and an alumnus of the same. He is also an alumnus of the TWAS Young Affiliate program and of the Global Young Academy (GYA). He is a Fellow of the African Science Leadership Program (ASLP) and a Fellow of the Nigerian Academy of Science. He has successfully supervised and co-supervised several M.Sc. and PhD students. He is currently the Director of Academic Planning and Quality Assurance, Redeemer’s University and also the Director of the Redeemer’s University African Centre of Excellence for Water and Environmental Research (ACEWATER).

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Case study: Air pollution in New York City

By Matt Burdett, 2 January 2020

On this page, we look at New York City as a case study of air pollution in one city and its varying impact on people.

Introduction to air pollution in New York City

New York City has long had a problem with air pollution. In 1953, 1963 and 1966, high pressure reduced winds which normally moved polluted air from the city, resulting in widespread health issues and even some deaths. In the twenty first century, air pollution continues to cause health issues across the city, as shown on the maps below.

• Health problems from air pollution in New York City. Source: ( One NYC, 2018 , p190).

However, on a global scale New York City’s air pollution is currently quite low. This page will look at the factors that have led to this low level of air pollution and the impacts of these strategies.

• Brooklyn’s pollution is a problem, but is very mild compared to some other cities such as New Delhi in India. Source: Popovich et al., 2019 . Data reflects regional estimates by Berkeley Earth based on observations at ground-level monitoring stations.

Causes of pollution in New York City

New York City’s Environmental Protection agency identifies several different types of air pollution. While some types, such as sulfur dioxide, may be relatively low, others such as ozone can be high. Being aware of the different pollutants is also important because they are caused by different emitters. Knowing this can help to tackle the problem.

The types of air pollutant and their main sources are ( NYC Environmental Protection, 2019) :

• Fine Particulate Matter (PM2.5) – all types of combustion sources
• Nitrogen Oxides (NOx) – emission from vehicles
• Elemental Carbon (EC) – fossil fuel combustion, including diesel exhaust
• Sulfur Dioxide (SO2) – fossil fuel combustion at power plants and other industrial facilities
• Ozone (O3) – motor vehicle exhaust, industrial emissions, and natural sources

New York’s response to air pollution

New York City has introduced several steps such as congestion charging (from 2020 onwards), switching taxis to cleaner fuels, and changing the oils used in heating. These are part of a wider sustainability plan.

Sustainability planning frameworks

In 2007, New York City began its first sustainability plan, known as PlaNYC. To achieve clean air, it set out fourteen initiatives that would reduce PM2.5 emissions by 40%. These were in five broad areas ( Charles-Guzman, 2012 ):

• Reduce vehicle emissions from roads
• Reduce general transport emissions (including ferries, trains and so on)
• Reduce emissions from buildings
• Develop natural solutions, such as planting trees
• Engage in research to develop further understanding of air pollution in New York

In 2015, PlaNYC was taken over by One NYC. One NYC is a comprehensive planning document that looks at all aspects of New York City’s future, including the issue of air pollution. It includes the stated goal “New York City will have the best air quality among all large U.S. cities by 2030” ( One NYC, 2018 , p188).

Specific strategies

The strategies mentioned below are not necessarily mentioned in the One NYC plan for air pollution reduction, but are all strategies that are being used that will reduce the problem of air pollution.

• Congestion charging

A congestion charge is a payment made by drivers who want to enter the city centre. Similar schemes have been very successful in other cities such as London where, since 2003, drivers have avoided paying the charge by not entering (and therefore not polluting) the city centre, or switching to cycling. The result in London is a drop of about 30% of vehicles in the city centre ( Edmond, 2014 ).

New York City’s congestion charge began on 1 January 2019 for some commercial vehicles ( NYC Taxi and Limousine Commission, 2019 ) and covered all of southern Manhattan. It is being extended in 2020/2021 to cover all vehicles and will be the first such scheme in the United States ( Durkin and Aratani, 2019 ).

• New York City’s congestion charge for taxis and limousines. Source: NYC Taxi and Limousine Commission, 2019 .

Clean air taxi fuels

Vehicles are subject to national standards decided by the US Environmental Protection Agency, so New York City cannot impose its own emissions standards on private vehicles, However, the PlaNYC and One NYC plans both included plans to convert the city-owned or controlled vehicles (such as dustcarts, cleaning vehicles and emergency vehicles) to more fuel efficient sources which pollute less. By 2012, over 30% of the city’s taxis had been converted ( Charles-Guzman, 2012 ) and by 2017 there were over 200 electric vehicle charging stations in the city.

The result was that between 2007 and 2015 the “overall fuel efficiency of the medallion taxi fleet climbed from 15.7 to 33.1 MPG [miles per gallon], and corresponding estimates of nitrous oxide and particulate exhaust emissions declined by 82 percent and 49 percent, respectively” ( Columbia University’s Mailman School of Public Health, 2019 ).

Switch to more efficient heating oils in buildings

New York City gets cold in winter, and most buildings are independently heated using oil burning systems. In 2010, the City legislated to reduce the sulfur content of some of the types of fuel used, and in 2012 the City launched its ‘Clean Heat’ programme which offered advice and financial and technical assistance to help owners change their buildings to better sources of fuel. Between 2012 and 2015, over 6000 buildings were converted most buildings to more efficient sources of fuel. This is projected to reduce related hospital visits by 700 per year and avoid 300 premature births due to the associated air pollution. ( New York City Department of Health and Mental Hygiene, 2016 ).

• Planting trees

New York City’s ‘Million Trees Initiative’ aimed to plan trees in among the existing city infrastructure including in parks, as part of new developments, and on streets. The initiative has multiple aims including flood water management, but the top reason for planting is to reduce atmospheric pollution ( NYC Parks, n.d. ).

According to the Million Trees Initiative, “one tree can remove 26 pounds of carbon dioxide from the atmosphere annually, the equivalent of 11,000 miles of car emissions. Our trees remove about 2,200 tons of air pollution per year, valued at $10 million annually” ( Million Trees NYC, 2015 ). The aim to plant one million trees by 2017 was exceeded and they were planted by 2015 ( Dumplemann, 2019 ).

These initiatives appear to have worked. As the map below shows, in all but a few central areas (some of which are where congestion charging will be introduced in the 2020s) air pollution has decreased.

• Citywide improvements in air quality between 2009 and 2017. Source: NYC Health, 2019 a.

It is not only PM2.5 particles that have reduced. All of the main pollutants have decreased between 2009 and 2017 ( NYC Health, 2019b ):

• Fine particles (PM2.5) -30%
• Nitrogen Dioxide (NO2) -26%
• Nitric Oxide (NO) -44%
• Black Carbon (BC) -30%

Perhaps most successfully, the amount of sulfur dioxide has declined by 96%, mainly as a result of the new regulations on heating oils used in buildings.

Charles-Guzman, 2012. Air Pollution Control Strategies In New York City:mA Case Study Of The Role Of Environmental Monitoring, Data Analysis, And Stakeholder Networks In Comprehensive Government Policy Development. https://deepblue.lib.umich.edu/bitstream/handle/2027.42/94532/Kizzy%20Charles-Guzman%20practicum%20120312.pdf?sequ

Columbia University’s Mailman School of Public Health, 2019. Clean air taxis cut pollution in New York City. In ScienceDaily. https://www.sciencedaily.com/releases/2019/05/190529131221.htm Accessed 3 January 2020.

Dumpelmann, 2019. How a Massive Tree-Planting Campaign Eased Stifling Summer Heat in New York City. https://www.discovermagazine.com/environment/how-a-massive-tree-planting-campaign-eased-stifling-summer-heat-in-new-york-city Accessed 2 January 2020.

Durkin and Aratani, 2019. New York becomes first city in US to approve congestion pricing. https://www.theguardian.com/us-news/2019/apr/01/new-york-congestion-pricing-manhattan Accessed 3 January 2020.

Edmond, 2014. 4 bold new ways New York is going clean and green. https://www.weforum.org/agenda/2019/04/new-york-city-goes-green-meatless-congestion-clean-air/ Accessed 3 January 2020.

Million Trees NYC, 2015. NYC’s Urban Forest. https://www.milliontreesnyc.org/html/about/forest.shtml Accessed 3 January 2020.

New York City Department of Health and Mental Hygiene, 2016. New York City Air Quality Programs Reduce Harmful Air Pollutants. https://www.healthypeople.gov/2020/healthy-people-in-action/story/new-york-city-air-quality-programs-reduce-harmful-air-pollutants Accessed 3 January 2020.

NYC Environmental Protection, 2019. Air Pollution & Regulations. https://www1.nyc.gov/site/dep/environment/air-pollution-regulations.page Accessed 7 November 2019.

NYC Health, 2019a. Health Department Releases Report on Improvements in Citywide Air Quality. https://www1.nyc.gov/site/doh/about/press/pr2019/health-department-releases-report-on-air-quality.page Accessed 2 January 2020.

NYC Health, 2019b. The New York City Community Air Survey: Neighborhood Air Quality 2008-2017. https://nyc-ehs.net/besp-report/web/report/6 Accessed 3 January 2020.

NYC Parks, n.d. Street Tree Planting. https://www.nycgovparks.org/trees/street-tree-planting Accessed 3 January 2020.

NYC Taxi and Limousine Commission, 2019. New York State’s Congestion Surcharge. https://www1.nyc.gov/site/tlc/about/congestion-surcharge.page Accessed 3 January 2020.

One NYC, 2018. One New York: The Plan for a Strong and Just City. https://onenyc.cityofnewyork.us/wp-content/uploads/2018/04/OneNYC-1.pdf Accessed 2 January 2020.

Popovich et al., 2019. See How the World’s Most Polluted Air Compares With Your City’s.

https://www.nytimes.com/interactive/2019/12/02/climate/air-pollution-compare-ar-ul.html Accessed 2 January 2020.

Case study: Air pollution in New York City: Learning activities

• Briefly outline the history and causes of air pollution in New York City. [3]
• Briefly summarise the differences between the PlaNYC and One NYC frameworks for sustainability. [2]
• Clean air fuels
• Efficient heating oils
• Evaluate the success of these strategies. [6]

Other tasks

Does your nearest city have an air pollution problem? Does it have an air pollution strategy? Write to a local government representative suggesting what they could do regarding air pollution and why. You may like to check the current levels of air pollution in your nearest city using https://waqi.info/#/c/7.085/8.785/2.4z

© Matthew Burdett, 2020. All rights reserved.

All secondary material on this site is clearly referenced and may be subject to copyright restrictions by the original authors. All original material on this page is subject to copyright.

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Open Access

Peer-reviewed

Research Article

Land suitability analysis in monocentric post-socialist city: Case of Ulaanbaatar, Mongolia

Roles Conceptualization, Data curation, Formal analysis, Methodology, Writing – original draft

¶ ‡ GB and GG are contributed equally to this work and Joint Senior Authors

Affiliation Department of Geography, Research Laboratory of Land Planning and Survey, National University of Mongolia, Ulaanbaatar, Capital City, Mongolia

Roles Conceptualization, Data curation, Formal analysis, Methodology, Resources, Writing – original draft

Roles Data curation, Investigation, Software, Visualization

Current address: Department of Geography, School of Arts and Scineces, National University of Mongolia, Ulaanbaatar, Capital City, Mongolia

Roles Data curation, Formal analysis, Methodology, Software, Writing – original draft

Affiliation School of Earth and Planetary Sciences, Curtin University, Perth, Western Australia, Australia

Roles Data curation, Investigation, Methodology, Software, Validation, Writing – review & editing

* E-mail: [email protected] (MI); [email protected] (MP)

Current address: Department of Land Management, School of Agro-Ecology, Mongolian University of Life Sciences, Ulaanbaatar, Capital City, Mongolia

Affiliation Department of Land Management, Mongolian University of Life Sciences, Ulaanbaatar, Capital City, Mongolia

Roles Conceptualization, Funding acquisition, Project administration, Supervision, Validation, Writing – review & editing

• Galmandakh Boldbaatar, 
• Gantulga Gombodorj, 
• Dorligjav Donorov, 
• Robert Andriambololonaharisoamalala, 
• Myagmarjav Indra, 
• Myagmartseren Purevtseren

• Published: August 15, 2024
• https://doi.org/10.1371/journal.pone.0308762
• Peer Review
• Reader Comments

Urban expansion has been rapidly increasing and is projected to be tripled in 2030 in worldwide. The impact of urbanization has adverse effects on the environment and economic development. Residential lands consist of almost one-third of the urban area and heavily affect the city’s inhabitants. The capital of Mongolia, Ulaanbaatar, has been significantly expanded, particularly in the urban periphery where poor living conditions and a lack of essential urban services were identified. The paper aims to conduct a suitability analysis of residential areas in Ulaanbaatar city based on three main categories (livability, affordability, and accessibility) of fifteen criteria using the fuzzy logic. Through the study, we have identified some potential suitable residential areas for further development, such as apartment residential area located in the southern part of the city and four low-rise ger areas were distributed along major transport corridors. Moreover, the results indicated that the spatial structure of the whole town might be in transition to a polycentric pattern. However, a concentric ring pattern in the ‘city’s periphery displayed a concerning uncontrolled ger area expansion, which may increase low living conditions in the area. This study recommends better urban sprawl control policies and more property market investment in the ger area to ensure sustainable development goals in Ulaanbaatar.

Citation: Boldbaatar G, Gombodorj G, Donorov D, Andriambololonaharisoamalala R, Indra M, Purevtseren M (2024) Land suitability analysis in monocentric post-socialist city: Case of Ulaanbaatar, Mongolia. PLoS ONE 19(8): e0308762. https://doi.org/10.1371/journal.pone.0308762

Editor: Walid Al-Shaar, AUM: American University of the Middle East, KUWAIT

Received: March 30, 2024; Accepted: July 30, 2024; Published: August 15, 2024

Copyright: © 2024 Boldbaatar et al. This is an open access article distributed under the terms of the Creative Commons Attribution License , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Data Availability: All relevant data are within the manuscript and its Supporting Information files.

Funding: This research was funded by the National University of Mongolia (NUM), research project and grant number: P2022-4385 and P2023-4621. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Competing interests: The authors have declared that no competing interests exist.

1. Introduction

According to the UN, the pace of urbanization is projected to be the fastest in many developing countries, facing challenges of uncontrolled urban growth and unstructured urban sprawl [ 1 ]. One prime example is capital city of Mongolia. The city’s population has increased fifteen times in the last few decades due to rapid rural-urban migration after the democratic revolution [ 2 ]. It has totally changed the pattern of the city to ger area expanding as 51.8% [ 3 ]. The impact of urbanization is adverse, creating environmental, social and economic problems globally [ 1 , 4 , 5 ]. Purevtseren et al. noted that air pollution, soil pollution, traffic condition, lack of essential services and poverty were serious problems in Ulaanbaatar city [ 6 ]. Moreover, severe damage to water resources was predicted due to city expansion [ 7 ]. The Ulaanbaatar city is the heart of the country, contributing 65% of the ‘country’s GDP, 85% of electricity power, and 50% of investments [ 2 ]. The uncontrolled urban sprawl in the Ulaanbaatar city may slow down the economic development and increase the environmental “footprints” of the country.

In 1933, ‘Athens Charter’ put forward a vision that residential land development is the top priority of a city, which is the heart of a functional town [ 8 ]. The uncontrolled residential land development drove many urban sprawl issues. For instance, Purevtseren et al. [ 3 ] found that 32% of the area in Ulaanbaatar city was covered by residential “ger” area (sprawl). According to the Japan International Cooperation Agency (JICA)’s questionnaire survey report, residents of Ulaanbaatar city have risen that security and environment were the most critical concerns of their sustainable life [ 7 ]. The essential aspect of a suitable and sustainable living environment in urban areas is good air quality and health and welfare services. Moreover, citizens commonly requested to locate the healthcare facilities near residential areas [ 7 ].

Furthermore, the typical monocentric spatial arrangement of the city was increasingly equipped in the city center throughout the Soviet era [ 9 ]. A significant population increase following the democratic revolution in 1990 created unregulated pressure on the city’s centralized spatial structure. Additionally, Bertaud [ 10 ] examined the spatial organization of cities in Central and Eastern Europe (CEE) and discovered that these regions have a monocentric spatial structure. Following market transitions, it observed a gradual transition to polycentric structures. Despite limited research on the monocentric spatial structure of Ulaanbaatar city, there is a noticeable presence of this kind of transition in this area.

Urban planning is consistently linked to a variety of decision-making difficulties and strategies, and the results of planning will differ based on the combination of the approaches and techniques employed. During the Soviet era, Mongolia, like many other communist nations, employed planning approaches and techniques to design cities without involving citizens. This resulted in a simple, quick, and interruption-free planning procedure during the project [ 11 ].

In our knowledge, in the Soviet era, a monocentric structure allowed the communist government to “control everything” related to urban management. According to the centralized economy, it was cost-effective and easy to manage particularly to build mega infrastructure and new residential district. The urban development process was implemented under “bulldozer urbanism” approaches, whereas all land had been owned by the state. There was no need for residents’ consent or negotiations with them to expropriate their lands. The municipality directly canceled the resident permit and gave notice to vacate the new development area by official declaration. This procedure referred to as “enter to ground” characterizes communist regimes’ relation to their people. For the new development areas, only the land capability for construction was considered, focusing on investigating the physical characteristics of ground soil and topography.

These days, many of these nations have new laws requiring public engagement while also using new approaches and technologies. One of the most difficult tasks facing communities and municipal governments today is to locate prospective locations for the sustainable growth of city subcenters without threatening human rights and environmental protection. Land suitability analysis offers tools to address these management problems [ 11 ].

Ulaanbaatar city’s monocentric structure hinders sustainable development promoting traffic jams, air pollution, land grabbing, etc. Several international and local experts suggested to replan and switch from monocentric to polycentric structures by developing new city subcenters in Ulaanbaatar [ 7 , 11 , 12 ].

In short, there has been a constant increase in interest in adopting land suitability analysis since it can handle and combine many types of data (both spatial and non-spatial, as well as multi-temporal and multi-scale) in an efficient manner. Then, from a technical perspective, comprehension of the fundamental issue, and democratic points of view can all benefit the planning process [ 11 ].

Therefore, it is now widely admitted that analyzing and identifying the suitability of residential areas is very important for appropriate land use policies to improve the living condition of citizens for future urban development [ 13 – 15 ].

To support sustainable urban development, a scientific and systematic approach for evaluating and planning the residential area development is essential. However, very limited research work in Ulaanbaatar city has been done. Such research may help the public, such as citizens justify their residential selection and real estate agencies, and land developers and investors make appropriate residential land development decisions.

The process of land suitability analysis involved multicriteria analysis (MCA) and geographic information system (GIS), and the land suitability evaluation methods have significantly improved due to the development of data science and GIS. Multicriteria analysis manages complex factors for suitability analyses and has been used in various industries [ 16 – 19 ]. The integration of GIS and MCA takes advantages of the professional field with publicity, productivity, efficiency, and accuracy [ 20 ].

However, determining the appropriate criteria is an essential and complicated step to achieving the scientific evaluated results [ 21 , 22 ]. The criteria of residential suitability analysis are multidimensional, generally including socio-economic and environmental factors, and their subdivisions into more exact criteria depending on the specification of research [ 23 ]. Commonly, natural conditions including slope, aspect, elevation, lithology, waterbody, green space and earthquake; and socio-economic conditions, such as demography, community accessibility, employment, housing, health, and safety, are mainly employed for residential suitability analysis [ 13 , 17 , 23 ]. However, the data availability and quality were mentioned as long-lasting challenges. As for popularity in this research field, a number of scholars demonstrated the integration of evaluation criteria as effective to develop the factors in the case study [ 22 ].

Many case studies have used MCA methods that include the ranking of the degree of strength and weakness by using the analytic hierarchy process (AHP) [ 11 ], ordered weighted averaging (OWA) [ 17 , 24 , 25 ], Bayesian networks [ 26 ], matter element [ 27 ], artificial neural network [ 28 ], agent-based model [ 14 ] and fuzzy logic theory [ 13 , 21 , 22 , 29 , 30 ]. Even though the usage of the MCA method is more popular, it still has several concerns. Firstly, data preparation and data quality are the issues that can heavily affect the results. The standardization of criteria is the next barrier that has more concern on mathematical simulation. Moreover, problems dependency of experts is remaining, such as the subjective uncertainty and some mathematical calculation for the standard quantification of evaluation factors [ 31 – 33 ]. Furthermore, in working with multiple criteria, it is complicated since the importance of criteria may vary. To minimize the subjectivity and mathematical shortcomings, the fuzzy logic theory, which was initially developed by Zadeh [ 34 ], was highly valued in the latest studies [ 24 , 35 , 36 ]. However, determining the membership of criteria, selecting fuzzy membership, and the criteria overlaying method still involve a certain level of subjectivity. Qualified references and validation were recommended to control the errors. The fuzzy logic theory is common in land suitability analysis, particularly residential suitability [ 29 ]. However, this method has not been used in the residential suitability and urban development industry in Ulaanbaatar.

Thus, for this study, we aim to develop a new framework for analyzing the residential suitability of Ulaanbaatar city using spatial analysis techniques (fuzzy logic theory), to evaluate the current residential suitability status and to provide commendation for future sustainable residential development. Moreover, the developed methods and outputs of this study may facilitate Ulaanbaatar urban development agencies to develop sustainable residential development policies and help citizens make a right residential location choice. The following objectives will be fulfilled in order to do this:

• Identify factors in case of Ulaanbaatar city based on literature review;
• Conduct suitability analysis using fuzzy AHP and Multi criteria analysis methods;
• Validate the developed model and recommend suitable areas for further residential development regarding Sustainable Development Goals (SDGs).

2. Materials and methods

2.1. study area.

Ulaanbaatar city is the Mongolian capital, located in the north-central part of Mongolia ( Fig 1 ). It is the country’s cultural, industrial, and financial hub, and the centre of Mongolia’s road network [ 3 ]. Ulaanbaatar covers approximately 4,740.4 km2, the equivalent of 0.3% of the total area of Mongolia (1.57 million km2). Ulaanbaatar has six central and three remote districts, and it is divided into 171 suburbs. It is the most populated city of Mongolia with approximately 1.8 million inhabitants, which accounts for 54.5% of the total population of Mongolia, with a population density of 308 people per km 2 [ 3 , 11 ]. Ulaanbaatar is the world’s coldest capital city, with an annual mean temperature of −1.3°C with its harsh winter climate minimum temperatures frequently falling below −30°C [ 37 , 38 ]. Geographically, the city is at an elevation of about 1,350 meters in a valley on the Tuul river, surrounded by mountains. Even though Ulaanbaatar city is not the largest capital cities globally ( Fig 1 ), it has been significantly expanded since the mid-twentieth century. For instance, in 1956, 118,000 residents were recorded in Ulaanbaatar [ 3 ].

• PPT PowerPoint slide
• PNG larger image
• TIFF original image

Data sources: DEM (elevation) based on Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) [ 39 ] (Available online: http://www.jspacesystems.or.jp/ersdac/GDEM/E/ ), river, and suburbs produced by the General Authority for Land administration, Geodesy and Cartography of Mongolia (ALMGC) [ 40 ] (Available online: https://nsdi.gov.mn/open-layer/ ). All sources are in the public domain and not copyrighted.

https://doi.org/10.1371/journal.pone.0308762.g001

2.2. Dataset

In this study, 25 types of data provided by The General Authority for Land administration, Geodesy and Cartography of Mongolia (ALMGC) [ 40 ], Research Laboratory of Land planning and survey, National University of Mongolia (NUM-Lab.RaS) [ 41 ] and National Statistics Office of Mongolia (NSO) [ 42 ] were used. Data of landscape for an illustration base map on all figures, particularly slope degree, was gathered from a subset of an optical stereo-based ASTER GDEM elevation data as well as radar-based SRTM elevation data from the CGIAR Consortium and the United States National Aeronautics and Space Administration (NASA) and the Ministry of Economy, Trade, and Industry (METI) of Japan [ 39 , 43 ]. Other sources for data and information inputs and figure representation belong to public organizations (ALMGC [ 40 ], NSO [ 42 ] and JICA [ 7 ]) or our laboratory (NUM-Lab.RaS) [ 41 ] listed below. The administration boundary, land use map, land price, road networks, heating supply network, water supply network, sewerage network, electricity network, railroad, land price and cadastral parcel and building were provided by ALMGC open-spatial data online portal [ 40 ], which were obtained through the authorized access rights by the authors. The data of schools, kindergartens, hospitals, bus stops, and air pollutions were collected from database of the NUM-Lab.RaS [ 41 ]. Finally, the census data were generated from the open data of NSO’s website [ 42 ].

Based on the literature and data availability, 15 different criteria were developed and processed in ArcGIS from ESRI ( http://www.arcgis.com ) platform ( Table 1 ).

https://doi.org/10.1371/journal.pone.0308762.t001

2.3. Methodology

2.3.1. defining residential suitability criteria..

The literature study of urban suitability analysis had carried on to select the necessary criteria for the study ( Table 2 ). According to the literatures and data availability, we categorize the 15 criteria into three types: livability, affordability, and accessibility. Slope, main parks, air pollution, water protection zones, crime rate, and land use belong to livability criteria. School, kindergarten, hospital, bus stop, shopping centre, central and sub-central business district (CBD), facility cover, and building cover were categorized as accessibility criteria. Land price with regards to affordability, the was the indicator.

https://doi.org/10.1371/journal.pone.0308762.t002

Regarding livability, the slope is the factor that can increase construction costs and the risks of soil erosion and landslide, and a slope smaller than 20 degrees was considered to be potential of any usage [ 20 ]. In Ulaanbaatar city, green space is scarce, within 10 kilometers and closer to the main park were considered to be an appropriate distance [ 2 ]. Air pollution of the study area represents PM10, and PM2.5 as the pollution levels from air pollution source points, and literature suggested that air pollution in Ulaanbaatar city was eight times higher than the safest level of World Health Organization (WHO). It revealed that the spatial pattern where remote area from high level were less polluted [ 38 ]. Environmentally, water is a serious concern, and within 50 m from water bodies, no construction activities are allowed, and it is also not suitable for residential and commercial usage [ 22 ]. The crime maps data are categorized using a modified version of the Jenks natural breaks classification method, aiming to minimize within-group variance and maximize between-group variance [ 48 ]. Crime rate shows a percentage of recorded crime per population in each suburb and was categorized into five classes from low to high. As for the land use (ALMGC’s land use map), undeveloped (land use code ““21””) and developed residential area (land use code ““22””), public land (land use code ““24””), recreational land (land use code ““25””), protected area (land use code ““61””) and open space (land use code ““11””) were selected and categorized into five classes ( Table 3 ).

https://doi.org/10.1371/journal.pone.0308762.t003

In terms of accessibility, school, kindergarten, hospitals, bus stops, shopping centre, central and sub-central business districts (CBD) have the highest score since they are essential for the residents [ 2 , 22 ]. Infrastructure and building density were categorized into five classes. Facility cover represents road network, heating supply network, water supply network, sewerage network and railroad network, and it reveals the percentage of cover on each suburb, and high level of coverage indicates high suitability [ 7 ]. Regarding building coverage, it was calculated the same as facility cover; however, a high level of building cover indicates a low score of suitability because the higher building density, the less potential for further development. A limitation for future development, such as a new house, infrastructure, green area etc.

Regarding land price, it was also classified into five categories, and lower price is suitable due to elevated cost for development [ 49 ].

2.3.2. Commensuration of the criteria.

To conduct residential suitability analyses, measurement scales of the criteria were required to be a competitive unit. We normalized criteria value ranging from 0 to 1. A number of different approaches were used in the literature, including deterministic, linear standardization and fuzzy logic theory. In this case study, we used the deterministic and fuzzy logic methods. In terms of the conventional deterministic approach, we rescaled criteria using a score range from 0 to 255. The crime rate, land use, facility cover, building cover and land price were classified into five categories representing suitability from very low (1) to high (5). Each class was rescaled as follow: ““Very low”” as 50, ““Low”” as 100, ““Medium”” as 150, ““Moderate”” as 200 and ““High”” as 255, and it was normalized by the maximum value ( Table 3 ). All rescaled criteria were simply normalized to be a competitive unit from 0 to 1 ( Fig 2 ).

Noted: (A) Distance from schools, (B) Water restriction zone, (C) Slope, (D) Land price, (E) Distance from the main parks, (F) Distance from the shopping, (G) Land-use type, (H) Distance from kindergartens, (I) Distance from hospitals, (J) Facility cover, (K) Crime rate, (L) Distance from CBD, (M) Distance from bus stops, (N) Building cover, (O) Distance from air pollution points. The criteria maps were created by the authors in QGIS ( https://qgis.org/en/site/ ). Data sources: criteria map A, H, I, M, O data of the NUM-Lab.RaS [ 41 ]; B, D, E, F, G, J, N were provided by ALMGC [ 40 ] (Available online: https://nsdi.gov.mn/open-layer/ ); C from a subset of radar-based SRTM data [ 43 ] (available online https://srtm.csi.cgiar.org ); K open data of NSO [ 42 ] (Available online: https://data.nso.mn/datamart ); L based on JICA study [ 7 ].

https://doi.org/10.1371/journal.pone.0308762.g002

All the classification methods of criteria are based on literature sources in Table 2 and below presented criteria classifications in detail ( Table 3 ).

2.3.3. Overlaying of the criteria.

Zimmermann and Zysno [ 52 ] discussed a variety of fuzzy overlay operations and highlighted five useful operators to combine independent datasets with the fuzzy AND, fuzzy OR, fuzzy algebraic product, fuzzy algebraic sum and fuzzy γ -operators. Based on the studies of suitability analysis, the results showed that a 0.9–0.95 fuzzy gamma coefficient has a high accuracy for the suitability map [ 53 – 55 ].

This “γ -operator” is a combination of the fuzzy algebraic product and the fuzzy algebraic sum, where γ is a parameter having values ranging from 0 to 1. If γ is 1, the combination is the same as the fuzzy algebraic sum while for a score of 0, the combination is equal to the fuzzy algebraic product. The parameter indicates where the actual operator is located between the logical ““and”” and ““or”” where μi is the fuzzy membership values for the i-th (i = 1, 2,…, n) maps to be integrated. The fuzzy algebraic sum operator is complementary to the fuzzy algebraic product. The result of this operation is always larger than, or equal to, the largest contributing fuzzy membership value. It means an increasing of possibility to obtain more suitable area.

2.3.4. Defuzzification.

The next step involved in the methodology is the defuzzification, which has two stages, a reclassification of the output of the model and generalization of final output into a final suitability map [ 56 ]. In the first step, we defuzzified it into six classes using the geographic equivalent classification method. Systematically evaluating the suitability of residential, the classification has been possibly explained as a linkage between urban development process and residential suitability. Moreover, the specification of the study area, the characteristic of the residential land was divided into two main features as apartment residential area (middle and high-rise residential buildings) and ger area (low-rise area with a house and traditional tent named as “ger” enclosed with fences) [ 3 , 57 ]. Finally, the classification of the degree of suitability was categorized as the most suitable, the second most suitable, moderately suitable, potentially suitable, marginally suitable and not suitable.

2.3.5. Accuracy assessment of criteria map.

Several accuracy metrics can be obtained from the confusion matrix. The percentage of incorrectly classified (omitted) data and overall accuracy are the two metrics that are most widely recognized [ 58 , 59 ]. By dividing the total number of pixels by the number of correctly classified pixels in relation to the data used as ground truth, the overall accuracy score provides an evaluation. It’s critical to understand the appropriate interpretation of each particular class in addition to the overall accuracy. The ’two standpoints’ approach of Story and Congalton [ 60 ] is typically used to determine the correctness of each particular class: the producer’s and user’s accuracy. The number of cases appropriately allocated classes is divided by the total number of that case classes [ 59 , 60 ].

The K statistics is a commonly used metric to assess map accuracy that may be obtained from a confusion matrix. It provides an indication of the chance of agreement between the map and the reference data [ 61 – 66 ]. We are used as the reference data the randomly selected and visualized ground control points from the high-resolution satellite image of Google Earth ( https://earth.google.com/web/ ) with field visited onsite manual evaluations.

Since the calibration of model not performed in the suitability evaluation steps, additionally employed the relative operating characteristic (ROC) curve and area under the ROC curve (AUC) value for the validation of criteria map [ 67 , 68 ]. AUC value (range of 0.5–1) close to 1 indicates perfect model with low bias and near 0.5 value shows low accuracy with random chance to predict. In practice, AUC values greater than 0.7 indicates that model/mapping has acceptable accuracy [ 69 , 70 ].

In our case, newly constructed or under construction residential blocks in the study area were counted as test data to evaluate accuracy of the produced suitability maps. All the processes of overall accuracy, K statistics and ROC curve (AUC) have been computed with the ArcGIS software (version 10.6) using ArcSDM tool (from Esri ( http://www.arcgis.com ).

Overall, the spatial structure of the city is a monocentric while the spatial pattern of the residential suitability is polycentric. One main suitable area and four small area were found as the most suitable for living and formed a concentric ring pattern on the resulted map ( Fig 3 ). Moreover, the result delineated that two main features of the most suitable residential area in the city, such as a high-rise residential area in the southern part of the city and a low-rise ger area in four small hotspots.

Noted: (A) Most suitable apartment area, (B) Most suitable ger and apartment area, (C), (D), and (E) Most suitable ger area. The residential suitability map was created by the authors in QGIS ( https://qgis.org/en/site/ ). Data source: The base map in this figure is from Geoportal of Mongolia’s (ALMGC) parcel map [ 40 ] (Available online: https://nsdi.gov.mn/open-layer/ ), and DEM (Elevation) subset based on the radar-based SRTM elevation data from the CGIAR Consortium [ 43 ] (available online https://srtm.csi.cgiar.org ).

https://doi.org/10.1371/journal.pone.0308762.g003

This study applied three main categories of suitability factors, including, livability, affordability, and accessibility from the assessment of 15 factors. Based on the final map’s spatial pattern, criteria related to accessibility heavily influence the suitability, including, distance from bus stops, schools, kindergartens, hospitals, shopping centers, CBD and facility cover. Criteria of livability and affordability have relatively lower influences on the resulted suitability map.

The final map indicated the residential suitability ( Fig 3 ). Approximately 3% (179.3 km 2 ) of the study area has suitability score above zero while the rest was identified as not suitable ( Table 4 ).

https://doi.org/10.1371/journal.pone.0308762.t004

However, the spatial pattern of Ulaanbaatar city is monocentric, a few small sub-centres have been created in the city ( Fig 3 ). Moreover, the city centre (CBD) is highlighted as a not suitable for residential apartment purpose, instead, a few areas in the south were found to have potential. The residential suitability is decreasing from those hotspots with the distance. In terms of total area, 4.9 km 2 is identified as the most suitable for residential purpose consisting of 0.1% of the total identified suitable area. Approximately 80% of the area is suitable for a residential apartment on the most suitable ( Table 4 ).

The most suitable residential site in the apartment area has been found in the south and central part of the city. The boundary of this area is featured by the central railroad in the north, along the north-south axis road it’s narrowing to south merging to the Tuul river creating the south-western edge, and central to south main avenue becomes the eastern boundary. It is administered as southwest district dominantly. The spatial pattern of the suitable area is clearly surrounding the most suitable area ( Fig 3 ).

In terms of potential areas, they are more likely to be connected with the most suitable area of ger area. However, new suburb development in southwest district, it’s the western, southern part of the area, is indicated as the most potential area.

Regarding the low-rise ger area, the number of the small hotspots is revealed on the map, and it is spatially clustered, unlikely to apartment suitability. In the north, locally known name as traditional old black-market area and north transport hub of ger area are found as the most suitable as the ger area residential. Second, the central part of the north western, locally known as west-arm area, is identified as the most suitable in ger area. Finally, in the south of the west, locally known as new city centre is outputted as a high level of suitability.

With regards to the second most suitability, spatially, it particularly surrounded by the most suitable location of residential apartment with a monotonic decreasing function. Moreover, it is also found with a large extent of area from the east part, north, and western part. Similarly, regarding the ger area, the most suitable hotspots are surrounded by the suitable area. It is noted that the classification of “the suitable” area is well distributed and surrounding the CBD, and 32.3 km 2 area is calculated (0.7% of the study area).

An error matrix was calculated to provide more details for the accuracy assessment. The overall accuracy is 0.85, meaning that 85% of the pixels were identically classified in the model and in the reference data, the result of the residential suitability and the 61 ground control points (GCPs) from the high-resolution satellite image of Google Earth ( https://earth.google.com/web/ ) visualization with field manual checks. This indicates that there is quite some good coincidence between the maps and GCPs. The Kappa coefficient also presents excellent agreement. A value of 0.82 indicates that the produced suitability map classes are about 82% better than a random assignment of these classes. However, it should be noted that the GCPs, besides random selection concerns, is also based on manual evaluation of the expert knowledge of authors, introducing same arbitrary criteria of performed model.

In the study, fuzzy AHP based residential suitability was divided into 6 classes. A total of 65 newly constructed or under construction residential blocks in the study area were selected as sample points (true positive) to evaluate accuracy of the produced suitability maps (false positive). ROC curve (AUC) has been computed with the ArcGIS software (version 10.6) using ArcSDM tool from Esri ( http://www.arcgis.com ) which is allowed to present graphically ROC curve and compute AUC value. Acceptable AUC value 0.74 indicates that performed suitability map has a sufficient degree of accuracy.

A reason for AUV value’s near to 0.7 could be the differences on the newly erected residential block buildings not always found perfect suitable sites for construction. While, fulfilling market demand construction company, land developer face lack of land supply for production and have to follow urban development plans which not based on suitability. Planning experts based their analysis on existing physical constraint, feasibility and construction factor data to locate residential development zone which is far from suitability and customers’ request.

4. Discussion

The study analyzed residential suitability in Ulaanbaatar city using fuzzy logic theory. As highlighted in the literature, the fuzzy logic theory was used to deal with suitability analysis in decision making [ 29 , 32 ]. It also involved more creativity than the traditional AHP approach [ 22 ]. The fuzzy AHP approach minimizes the subjective importance of the criteria and is the sophisticated method to deal with the uncertainty of an expert’s knowledge bias. Ustaoglu and Aydinoglu [ 22 ] emphasized that urban suitability maps obtained from the fuzzy method provide a better interpretation of the land use characteristics. However, a more specific study is suggested for residential suitability analysis. Our finding suggested that the result from the selected method showing a competitive output.

Regarding the delineated boundary residential suitability area, approximately 3% of the city is identified with a suitability score from the lowest to highest (0–73), and it has created the residential suitability boundary ( Fig 3 ). Apparently, this boundary closely matches with the boundaries that were found in other studies. JICA [ 7 ] highlighted the north edge of prohibition urban development, and further from this boundary, it was identified to plan green area where is essential to the environment for sustainable city development. Erdenechimeg et al. [ 57 ] noted that the ger residential area categories as central area, mid-tier area, fringe area, apartment area and summer camp green space settlements. The boundary of the fringe ger area and summer camp green space settlements were almost matched with our findings. Moreover, a recent case study of urban sprawl in Ulaanbaatar city showed the suitable area of settlements, and the result is relatively similar with both the boundary and the sub-centres [ 71 ]. However, it can be said that those matching boundaries could be representing a weak feature of centralized infrastructure development, including road network, heating supply network, water supply network, sewerage network and the railroad network, and accessibility of basic services. Historically, the ‘city’s spatial structure is traditional monocentric, which tend to more equipped in the city centre in the Soviet era [ 9 , 10 , 49 ]. After the democratic revolution in 1990, a lack of urban development policies and immature land market during the unprecedented period with significant population growth pressured to form the uncontrolled and centralized formation of spatial structure in the city. However, it is unclear to define the border of the developing area of the city, caused of imprecise components and a subjective methodology. As a result, it enables a subjective influence on urban plans. Moreover, urban planners and decision-makers have acknowledged a circumstance that city problems related to environment, society, economy, transportation, infrastructure, and spatial planning are not possible to fully determine before the planning process. One of the prime steps in formulating the Ulaanbaatar master plan is “an evaluation of complex assessment for urban development”. However, in this assessment, 65 factors of 4 categories, including environmental (26 factors), societal and economic (20 factors), infrastructural (8 factors), architectural, and landscape (8 factors) are evaluated, and the scoring is limited from 1 to 5 with arithmetic average [ 12 ]. Furthermore, the scoring of the evaluation did not recognize the spatial parameters (geometry). As a result, assessment is not possible due to inadequate information for spatial planning. Therefore, the proposed methodology should be made essential in planning projects, since our study’s results clearly show the benefits of taking residential suitability analysis using fuzzy logic into consideration when examining suitability for new residential area development.

Furthermore, Bertaud [ 10 ] analyzed the spatial structure of Central and Eastern European (CEE) cities and found that it has a monocentric spatial structure causing a centralized command economy, maintaining their prestigious cultural centre, and converting to a polycentric structure slowly after their market transitions. Generally, one of the key changes in our results is that the monocentric spatial pattern is converting slowly into a polycentric structure ( Fig 3 ). Regarding a high-rise apartment residential area, surprisingly, CBD is not identified as the most and second suitable site according to our findings, and the pattern of CBD has been changing to be mixed and converting to multi-purposes activities [ 3 , 6 ]. Moreover, the value of the residential area in CBD is slowly dropping due to inappropriate living condition, including a high density of building, underdeveloped public transportation, lack of green space and air pollution, indicating to develop and maintain in CBD as a cultural or business centre. UN [ 1 ] also noted this urbanization consequences, and government policy, regulation on urban development and investment responses market liabilities are the primary victims based on the CEE cities [ 1 , 9 ]. Moreover, the real estate market plays a vital role in city development, open information about prices, the business environment of real estate agent, clear land and property tenure, property registration institution, the flexibility of land use change, subsidies and taxation policy [ 49 ]. Ulaanbaatar city has demonstrated a similar spatial pattern of residential suitability. Since the economic capital of the citizens has increased, mid and high-societal groups are starting to prefer urban fringes or preurban agricultural areas for residential propose, compared to the socialist era, where CBDs were in high demand. Ulaanbaatar City’s housing market immediately reflected that kind of "close to nature" choice and private land developers started small residential development projects in suitable urban fringes, which are gradually changing an urban monocentric structure to a polycentric one.

It’s evident, that Ulaanbaatar is the oldest urban center in Mongolia with a history of more than 700 years. The monocentric structure of the city had been created and administrated without land market implications during the Soviet era, with most urban growth of that time. This period saw land nationalization and centralized administrative allocation, impacting the internal spatial pattern of the city defined as prominent centers with extensive, radial, and concentric transit networks reinforcing their monocentric structure [ 72 ]. The combination of the centralized location of the national institutions, the main role in the domestic economy, and the high rate of urbanization in the post-socialist city founded insecure property rights, institutional disorganization, governance problems, and weak urban planning regulations. Mongolia’s transition to a market economy was formed in the 1990s through the legal reform of numerous legal frameworks about land and property, including the Land Law, the Law on Allocation of Land to Citizens of Mongolia for Ownership, and the Law of Urban Development. Initially, the government proposed free land policy accelerated the market economy, helped the reduction of poverty, and allowed poor urban residents of slum districts (ger area) to own valuable residential land plots as immovable property. However, the free land policy harms urban management, accelerates urban expansion in city fringes, and creates difficulties in infrastructure construction, private owners refuse new development plans, increasing land speculation and corruption in the public sector.

The legal frameworks empower the local government of the capital city to organize land allocation, and public participatory planning principles are to be applied and reflected in urban development plans and activities [ 72 – 74 ]. Even though Mongolia has changed its urban regulation and administrative system, the historically centralized administration on the monocentric structure somehow exists and impacts the urban expansion on spatial patterns [ 9 ].

Regarding the most suitable area of apartment residential, the south and central part of the city is determined where indicates appropriate infrastructure, an accessible distance of basic services, CBD, and main park, a reasonable level of air pollution and crime rate ( Fig 3 ). Moreover, the income level of residents in this suburb is sufficiently high with the poverty rate is less than 6%, according to the report of the World Bank [ 2 ].

With regards to ger area, four hotspots of the most suitable low rise ger area are the main indicators for the conversion of polycentric spatial structure. ADB [ 75 ] and JICA [ 7 ] recommended sub-centre locations on Ulaanbaatar Master Plan 2040, and they were almost the same locations as the most suitable hotspots of our study [ 12 ]. However, almost 40% of resident in ger area was identified as multidimensional poverty and high level of unemployment on The World Bank report [ 72 ]. Even though the location of those sites is the core of sub-regions as the most suitable ger residential, living condition is incomparably lower than apartment residential area ( Fig 3 ). Furthermore, Singh [ 2 ] highlighted three dynamic factors for the low-density spatial pattern of Ulaanbaatar, including the traditional planning system and free land ownership, the unmatched urban plan with population growth after 2000. The main problem is the lack of centralized infrastructures, such as sewage, water supply, sanitary facilities, roads, and a public transportation system [ 57 ], and it is essential to improving living standard and filling the lack of basic services [ 75 ].

Regarding the potential for residential, the hotspots of most suitable for the low-rise ger area would be ideal for future developments. Also, for the high-rise residential area, the second most suitable category is preferable. Moreover, the number of locations would be the potential of suitability, if the condition of livability and accessibility are improved, including in low-rise ger area close to mid-rise residential area of CBD. Similarly, as the Ulaanbaatar city master plan 2030, experts of JICA found and recommended that the restriction in the east, north and south for the urbanization of Ulaanbaatar city has to be taken in 2009 [ 7 ]. They only suggested promoting the urban expansion into the west due to environmental concerns in sustainable city development. Moreover, Gantumur et al. observed that the prediction of urban growth in 2030 and 2040 is projected toward the western and eastern part limited by the mountains [ 76 ]. Overall, based on the literature and our results, the potentiality of residential development depends on accessibility, and the southern and the western part of the city would be the most suitable for future development while some conditional development suggested the east and northern areas.

In term of the unsuitable residential area (99.93 km 2 ), it’s expanding significantly [ 6 , 71 ] due to rural migration and free land policy implementation after 2002 [ 2 , 52 ]. The Law on Land (2002) grants Mongolian citizens, regardless of age and sex, one free land plot until May of 2028, in Ulaanbaatar city. According to the Land Inventory report [ 72 ], 277537 citizens owned land, and it was only 16.7% of the residents of the capital city. Despite the abundance of land plots owned by residents, there is still a significant need for 9715.5 hectares of land in Ulaanbaatar city [ 74 ]. The impact of free land policy is severe in the city, even though it is a market economy, residential ger area land is administratively allocated free for residents without a proper urban plan and basic infrastructures [ 72 – 74 ]. Once the land was allocated, it was almost never recycled since the difficulties of legislation for land-use recycle and urban development on the government decision [ 49 ]. The free land policy resulted in the absence of land prices, removing all economic incentives to the land use recycling process in the city [ 49 , 72 ].

As a result of this phenomenon, low-rise ger area continuously expands in the urban periphery with a low living condition, accelerating multidimensional poverty. Moreover, it is forming a spatial pattern of a concentric ring in the city and added by this process. Similarly, in Moscow and CEE cities, this phenomenon was observed and noted in the persistence and uniformity of housing types in successive rings [ 9 , 49 ]. Furthermore, whether in ger area or in sub-centre, households tend to be concentrated in the periphery with a low developed infrastructure, this spatial pattern is led to the increase of costs of living and pollutions.

5. Conclusions

To conclude, key changes are observed from the results, and it can be said that the city spatial pattern of residential suitability is changing to polycentric structure slowly. Firstly, the spatial pattern of residential suitability in Ulaanbaatar city is in a stage of an ongoing process of suburbanization, which indicates that the centre of the city (CBD) is not suitable for residential purpose. Secondly, the most suitable is only an area of 4.9 km 2 , and almost 80% of the category was determined as a high-rise residential area, found in the southern part of the city. Thirdly, approximately 3% (179.3 km 2 ) of the study area is evaluated as a suitable while the rest is identified as unsuitable. Moreover, the ger area is the most important part of the spatial pattern of residential suitability, the specific living condition to consider for further urban development. Moreover, the ger area tends to expand through the progressive addition of concentric rings in the periphery of the city due to the distortion of the land market.

Further study should use more accurate data and identify the necessity of basic services (school, kindergarten, bus stop, hospital, public services, social services, green space, playground), road, central infrastructure access (water, heating, transport, sanitary) on each suburb.

Supporting information

S1 fig. auc of suitability map..

AUC is computed with the ArcSDM tool of ArcGIS software (version 10.6) from ESRI ( http://www.arcgis.com ).

https://doi.org/10.1371/journal.pone.0308762.s001

S1 Table. Accuracy assessment result.

https://doi.org/10.1371/journal.pone.0308762.s002

Acknowledgments

The authors acknowledge all the data providers, especially the General Agency for Land Management, Geodesy and Cartography of Mongolia, Research Laboratory of Land Planning and Survey, National University of Mongolia and JICA. Lastly, we would like to express our sincere gratitude to Jianhong (Cecilia) Xia, the editors and two anonymous reviewers for their constructive suggestions, which greatly raised the quality of the paper.

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• Published: 13 August 2024

Unintended food safety impacts of agricultural circular economies, with case studies in arsenic and mycotoxins

• Christian Kelly Scott   ORCID: orcid.org/0000-0002-4869-9151 1 &
• Felicia Wu   ORCID: orcid.org/0000-0003-0493-0451 1 , 2  

npj Science of Food volume  8 , Article number:  52 ( 2024 ) Cite this article

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• Plant sciences
• Risk factors

For millennia, food systems worldwide have employed practices befitting a circular economy: recycling of agricultural and food waste or byproducts, environmentally sustainable production methods, and food preservation to reduce waste. Many modern-day agricultural practices may also contribute to a circular economy through the reuse of waste products and/or reducing agricultural inputs. There are, however, food safety impacts. This paper describes two sustainable agricultural practices that have unintended positive and negative impacts on food safety: alternative rice cultivation practices and no-till agriculture. We highlight how alternative rice cultivation practices have intended benefits of water conservation and economic savings, yet also unintended effects on food safety by reducing foodborne arsenic levels while increasing cadmium levels. No-till agriculture reduces soil erosion and repurposes crop residues, but can lead to increased foodborne mycotoxin levels. Trade-offs, future research, and policy recommendations are discussed as we explore the duality of sustainable agricultural practices and food safety.

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Introduction.

Agriculture in the circular economy is often referenced in terms of sustainable food systems. While minimizing food waste, food loss, and pollution is often the introductory entry point into the discussion of food, the interconnectedness of the principles of the circular economy also includes repurposing/reusing products and materials and regenerating natural systems 1 , 2 , 3 .

Yet another important component of sustainability is health—not only the health of ecosystems but also human health. Agricultural practices focused on advancing the usefulness of byproducts, like crop residuals and soil management, and/or practices that focus on regenerative cultivation techniques to conserve water and limit inputs, like alternate wetting–drying cultivation (AWD) and furrow irrigation (FI), can have important unintended impacts on food safety—with either human health risks or benefits. Figure 1 demonstrates where these issues fit conceptually within the circular economy. In this paper, we present the evidence of unintended food safety impacts stemming from agricultural practices generally regarded as sustainable: alternative cultivation practices for rice (ACP) and no-till agriculture, in the circular economy and the resulting food system.

Figure shows the progression of sustainable production in an orange circle containing a self-loop and a progression to a blue sustainable use circle. Sustainable use circle contains a self-loop and a progression to yellow circle recycling/reusing. Recycling/reusing is linked to sustainable production. No-till agriculture text box is placed within the recycling/reusing circle. Alternative cultivation practices for rice text boxes are placed in the sustainable production circle. The figure demonstrates alternative cultivation practices for rice are a form of sustainable production through reduced water use, no-till agriculture prevents soil erosion and reuses crop residue for soil protection and nutrients, and sustainable use of water and residues relates to both these practices. Authors original creation referencing van Buren et al. 3 and Helgason et al. 2 .

The current global food system is arguably less oriented around sustainability and more focused on economic viability and food availability. As a result of this emphasis, agricultural production has increasingly moved towards large-scale production, crop monocultures, mechanized farming, and yield maximization. Conventional market production for agricultural products is both highly resource-intensive (land, water, chemical inputs, fossil fuels) and impactful to the environment. A shift in agricultural production away from conventional practices can help to abate these concerns. For many, novel agricultural practices that are integrated into the circular economy paradigm represent the way forward: a focus on sustainability in the food system while improving access to safe, sufficient, healthy, and nutritious food for the world’s growing population.

In the circular economy, a change in agricultural policy or practice that is focused on one aspect of the food system sector can have numerous unintended impacts in other areas. For example, previous work focusing on agricultural products resulting from the circular economy includes the promotion of oilcakes that reduce food waste having unintended anti-nutritional impacts on human food and animal feed 4 . By contrast, plant byproducts in the application of the circular economy in the food system can have positive unintended impacts through human consumption of more nutritional products 5 or environmental benefits of using fewer chemical inputs 6 . Other scholars have noted that targeted changes focusing exclusively on food safety can have widespread unintended impacts throughout the economy and food system 7 .

However, in this area of growing scientific inquiry, little attention has been given to how agricultural practices regarded as sustainable may have unintended consequences on food safety. In the examples presented below, we demonstrate how those risks can unintentionally be decreased with ACP of rice or increased with no-till cultivation.

Alternative cultivation practices for rice: reduced water use and food safety benefits and risks

For thousands of years, rice has been cultivated around the world in highly water-intensive ways: most often, farmers will keep paddies continuously flooded from early rice plant growth stages through to harvest. Indeed, continuous flooding can be regarded as the conventional rice production method worldwide. Alternative cultivation practices for rice (ACPs), on the other hand, are methods to reduce water use throughout the rice growing season. Two practices that are receiving growing attention in this area are alternate wetting–drying (AWD) and furrow irrigation (FI) cultivation. AWD is the practice of intermittent flooding of fields as opposed to keeping a field flooded throughout the growing stages of the crop. FI is the practice of cultivating rice along elevated beds to deliver water to plant roots from an irrigation system pumping water into furrows without flooding the entire field.

These ACPs have gained traction for three primary reasons relating to the circular economy paradigm: water conservation, reduced greenhouse gas emissions, and reduced input costs. However, the traditional continuous flooding method of rice production had its rationale in maximizing yield and reducing weed damage. Therefore, a reasonable concern is whether ACPs can provide rice yields similar to those afforded by conventional continuous flooding production.

In addition to these economic considerations, an important question is whether using ACPs can reduce the uptake of soilborne arsenic into rice. Arsenic, a naturally occurring metalloid in soil and water, has been known for thousands of years to cause toxicological effects in humans and other animals. Today, humans worldwide are exposed to arsenic through drinking water and food. Under continuously flooded conditions, rice plants take up soilborne arsenic easily through all parts of the plant, including the rice grains. If the soil is not continually wet, arsenic uptake is reduced. Hence, in both AWD and FI cultivation practices, lower arsenic levels may accumulate in rice. This would be an additional benefit of these ACPs. Conversely, however, any soilborne cadmium (also naturally occurring in water and soil) may be taken up more easily when soil is dry: the difference in these cases is that soilborne arsenic is often in the form of anionic metalloids (more easily taken up by plants in wet conditions), while soilborne cadmium is in the form of cationic metal ions (more easily taken up by plants in dry conditions).

No-till agriculture and the risk of foodborne mycotoxins

No-till agriculture refers simply to the practice of forgoing tilling (turning over the soil) on farmlands, either before planting, after harvest, or both. Tilling is common on agricultural fields to remove weeds at the start of the planting season, as well as to remove crop residues after harvest. This practice can, however, increase risks of soil erosion and loss of important soil nutrients for crop plants. No-till agriculture is seen as a potentially more sustainable method of farming; crop residues after harvest are left on the soil to protect nutrients and to prevent erosion.

However, when crop residues are left on farm fields, they can harbor microorganisms and fungal sclerotia, which can then infect the crops planted on those fields in the next season. In the case of overwintering fungi that then colonize crops in the next season, the risk is that some of these fungi produce mycotoxins (fungal toxins) that cause a variety of adverse health effects to humans and animals. The state of the evidence linking no-till practices to mycotoxin risks in subsequent seasons is explored in this paper.

Alternative cultivation practices for rice: impacts on yield, water use, and arsenic levels

The link between alternative cultivation practices (ACPs) for rice production and targeted outcomes (both positive and negative) has been examined in multiple studies, shown in Table 1 . These ACPs—specifically, alternate wetting–drying and furrow irrigation—have been tested extensively and shown to reduce water usage and abate water scarcity concerns 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 . The practices are useful for the environmental conservation of fresh water and reducing the economic costs of farmers by reducing the use of inputs (like fuel used to power irrigation in AWD) 8 , 15 , 26 , 27 , 28 , 29 . The practices reduce run-off from fields and aid in rainfall capture efificacy 8 , 15 , 25 , 30 , 31 . AWD and FI have also been shown to reduce greenhouse gases and emissions compared to continuous flooding 10 , 32 , 33 , 34 , 35 , 36 , 37 . These benefits are notable, given evidence that suggests that, under the proper conditions, there is no reduction in yield in AWD or FI rice compared to continuous flooding cultivation 8 , 10 , 11 , 12 , 13 , 14 , 17 , 18 , 19 , 20 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 . These are practical financial and environmental reasons for ACPs to further the principles of the circular economy while preserving rice farmers’ overall profitability.

Nonetheless, it is important to consider the food safety impacts of these ACPs. In continuous flooding (conventional) cultivation, the anaerobic conditions lead to increased phyto availability and uptake of soilborne arsenic by rice plants 46 , 47 , 48 , 49 . Arsenic is a metalloid that occurs naturally in soils and water worldwide and causes multiple adverse effects in humans: acute toxicity at high doses, several human cancers—most notably lung cancer, skin cancer, and bladder cancer, hyperkeratosis and black foot disease, and cardiovascular disease 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 . In multiple studies worldwide, AWD and FI cultivation practices have shown reduced arsenic levels in rice 8 , 10 , 15 , 30 , 39 , 43 , 44 , 45 , 46 , 60 , 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 . These studies are summarized, with corresponding arsenic reductions in ACPs vs. continuously flooded rice, in Table 2 . In practice, therefore, these ACPs could reduce human exposures to foodborne arsenic, with potentially significant health effects—especially for populations where rice is a dietary staple. Indeed, policymakers worldwide are increasingly focusing on reducing arsenic in food. In the United States, the Food and Drug Administration (FDA) is implementing a Closer-to-Zero Action Plan, with the intent of setting action levels for foodborne arsenic, cadmium, lead, and mercury by 2024. This was followed by a US Congressional Report in 2021, describing high levels of arsenic, cadmium, lead, and mercury in infant foods pulled from grocery shelves 71 , 72 , 73 , 74 . As rice is a common component not just in adult diets but in infant foods, it is all the more critical to find methods to reduce arsenic levels in rice.

ACPs, however, are not uniformly beneficial to human welfare and the environment. ACPs can be tactically demanding compared to continuously flooding rice 8 , 10 , 12 , 75 , 76 . If a field has soils that dry out quickly, yields can be reduced substantially, even if the other benefits of the practice, such as arsenic reduction, are increased 10 , 12 , 23 . In general, ACPs are often associated with reduced yields compared to continuous flooding cultivation 12 , 44 , 66 , 77 , 78 . Many studies have examined the relationship between rice yields under conventional vs. alternative cultivation practices, summarized in Table 3 . Adoption of ACPs has been slow because they are often difficult to scale up, and, in the case of quickly drying soils, present potential economic risks to farmers who cannot afford to switch rice cultivation techniques for a relatively unproven practice 8 , 10 , 12 , 13 , 27 , 28 , 79 . Some studies suggest that ACPs may be related to decreased carbon availability in soils 80 , 81 , 82 .

There is a countervailing potential food safety risk as well, in that drier soils have increased bioavailability of cadmium that can be taken up by the plants, thereby increasing the consumption of the harmful metals and metalloids in diets 39 , 66 , 68 , 83 , 84 , 85 . Several studies have demonstrated the link between ACPs and increased cadmium uptake in rice, as shown in Table 4 . Cadmium exposure has been associated with diverse cancers and with neurotoxic and nephrotoxic effects 86 . This is far from an ideal solution, with increased exposure to cadmium as arsenic decreases in alternate wetting-drying rice production. Even so, from a public food safety risk perspective, arsenic is generally regarded as the more toxic element compared to cadmium, from a human health perspective 87 . Moreover, interestingly, cadmium uptake in rice has been shown to be correlated with other essential elements such as copper and selenium 88 , which may help to reduce the biologically effective dose of cadmium in the body. Hence, in a literal ‘pick your poison’ decision, reducing arsenic levels through ACP has been considered preferable to reducing cadmium levels in continuous flooding cultivation 39 , 68 , 87 . Nevertheless, ACPs are not all-or-nothing strategies, and farmers must often weigh the specific amount of flooding and dry field management in a manner that provides an optimal reduction in both arsenic and cadmium uptake by their crops 39 , 68 , 87 , 88 , 89 .

No-till crop cultivation: impacts on mycotoxin concentrations in crops

Mycotoxins are toxic and carcinogenic chemicals produced by fungi that colonize crops 90 . Among the most agriculturally important mycotoxins worldwide are aflatoxins, produced primarily by Aspergillus flavus and A. parasiticus ; fumonisins, produced primarily by Fusarium verticillioides and F. proliferatum ; deoxynivalenol (DON, vomitoxin) and zearalenone, produced primarily by F. graminearum and F. culmorum ; and ochratoxin A, produced by Penicillium verrucosum and A. ochraceus 91 . These mycotoxins, which can co-occur in field conditions 92 , cause a diversity of harmful health effects in humans and animals, ranging from liver cancer to neural tube defects in babies to immunosuppression and growth impairment. These fungi frequently colonize crops such as maize, nuts, and cereal grains in the field, where they may produce these mycotoxins; and can also continue to grow in storage or to overwinter in fields, particularly if crop residues are still present.

One growing practice that is often discussed in the context of the circular agricultural economy is no-till agriculture—in which crop residues play a key role. No-till agriculture is a practice of soil management that involves minimal disruption of the topsoil both before planting and after harvest. Where much of the conventional contemporary farming practices involve turning over the topsoil and crop residues following the harvest to prepare the soil for the next season’s crops, no-till farming involves minimal soil disturbance between harvest and planting and typically means leaving crop residue on fields. The practice of no-till agriculture has several important economic, environmental, and health benefits: it can preserve soil organic carbon, improve biodiversity, reduce soil erosion, reduce labor and agricultural input costs, and reduce emissions of PM 2.5 93 , 94 , 95 , 96 , 97 .

However, the discourse around no-till farming has almost exclusively focused on comparison to conventional tilling of agricultural and environmental outcomes, such as yields, soil health, weed abundance, and ecosystem services; with little attention given to the quality and safety of the food crops produced in each scenario 98 , 99 , 100 , 101 . Indeed, non-tilled soils may retain harmful characteristics that conventional tilling could reduce or eliminate. It has been shown that pathogens may survive more efficiently and colonize the following season’s crops under no-till conditions 102 , 103 , 104 , 105 . Untilled soil may result in immobilized nutrients, leading to problems with crop nutrition availability and uptake 105 , 106 , 107 . In many commercial fields, no-till cultivation has led to greater use of chemical controls for pests and weeds because these are not cleared from the field as they would be if tilled; which may increase human health and ecosystem risks from pesticide and herbicide exposures 101 , 108 . Specific to food and feed safety, the primary concern of no-till agriculture’s effect on the crops grown in following seasons is what some authors have described as ‘the mycotoxin problem’ 109 , 110 , 111 .

Under no-till agricultural cultivation, crop residues left in the field serve as a refuge for fungal sclerotia to overwinter in the field: to survive between harvest and the next planting. These sclerotia can serve as an inoculum for fungal infection on crops grown in the following season 110 , 111 , 112 , 113 , 114 . This can pose a food safety danger in that certain fungi produce mycotoxins that contribute to cancer, immunosuppression, and growth impairment in humans; as well as economic losses to farmers 115 , 116 , 117 , 118 . The explicit link between the targeted fungal species/fungal mycotoxins and no-till agriculture has been examined in a wide variety of contexts—mycotoxins, fungi, crops, and different geographic regions worldwide—shown in Table 5 . While several studies did not find any significant differences in fungal infection rates and mycotoxin levels in no-till vs. conventionally tilled fields, the preponderance of evidence to date is that no-till agriculture results in higher levels of fungal infection and subsequent mycotoxin contamination in crops grown in no-till agricultural conditions.

Given the food safety (and other previously mentioned) concerns, a careful balance between ecological, health, and economic factors must be calculated by farmers in choosing a tillage system for their crops. This is simultaneously a public health, agricultural science, and livelihood-economic calculation. If the agricultural products that farmers produce exceed the limits of consumable mycotoxins, they cannot be sold for human or animal consumption, due to regulations on allowable mycotoxin levels in over 100 nations worldwide. Further complicating the matter is that mycotoxins are expected to become a greater risk in the future due to near-term climate change impacts 118 , 119 , 120 , 121 .

When the agricultural circular economy is discussed in the context of sustainable food production, it is important to consider food safety and food quality impacts. In 2016, Stahel 122 wrote of the circular economy paradigm: “It would change economic logic because it replaces production with sufficiency: reuse what you can recycle what cannot be reused, repair what is broken, remanufacture what cannot be repaired.” Later, he states that this paradigm applies to “arable land;” grouped with his discussions of cars, buildings, mobile phones, and cultural heritage. Indeed, since this writing, agricultural studies have examined applications of the circular economy to promote sustainable food production practices. However, somewhat differently from other applications of the circular economy listed in Stahel’s article, food safety and its attendant human health effects must be key considerations when it comes to agricultural contexts.

In this review, we described two very different and arguably sustainable agricultural practices befitting of the “circular economy” designation: alternative cultivation practices (ACPs) for rice production that use significantly less water than the conventional continuous flooding method and no-till farming. In both cases, these practices reduce certain important agricultural inputs such as water and labor, and foster other environmental benefits such as reduced carbon emissions and reduced soil erosion and PM 2.5 emissions. However, the food safety effects of these practices must be considered in a truly circular paradigm.

In the case of alternate wetting–drying and furrow irrigation production methods of rice production, a key food safety benefit is the reduced uptake of soilborne arsenic into rice grains. This could translate into significantly lower foodborne arsenic exposures, which could lead to meaningful health benefits in populations worldwide where rice is a dietary staple. On the other hand, there is some evidence of increased cadmium uptake in rice grains when ACPs are employed—a tradeoff resulting from the anionic vs. cationic natures of arsenic vs. cadmium in wet or dry soil. The extent to which these concentrations may differ in rice grains under different cultivation practices and the imputed human health effects are important areas to study in the future; as around the world, rice farmers may adopt these ACPs at higher rates due to meeting new food safety standards. Other means of reducing arsenic and cadmium exposure through rice include removal of the hull and bran, which typically bioaccumulate more of these metals; and soaking rice grains and discarding the water before cooking.

In the case of no-till agriculture, diverse microorganisms, including mycotoxigenic fungi, are more likely to survive in fields that contain crop residues—which are common in untilled fields. The overwintering fungi can then colonize the crops planted in the subsequent season, and produce mycotoxins on those crops that pose health risks to humans and animals. There is a large body of evidence for the five most agriculturally important mycotoxins—aflatoxins, fumonisins, deoxynivelanol, zearalenone, and ochratoxin A—that no-till agriculture increases the risk that the fungi that produce these toxins will colonize food crops. Because the aforementioned mycotoxins cause such a wide diversity of serious health effects, this food safety issue must be taken into account when considering the benefits and costs of adopting no-till farming systems. While tilling is far from the only solution to reduce mycotoxin risks—others include good agricultural practices in the field, improved (cool, dry, pest-free) food storage practices, and a variety of plant breeding and chemical application strategies—tillage choices by farmers can have an important impact on this key food safety risk.

Incorporating food safety considerations into sustainable agricultural practices is crucial and, in fact, fulfills the true “circular economy” paradigm by extending to human health effects. Healthier populations are better able to sustainably produce safe and nutritious food worldwide, and the circular nature of human health and agricultural production can result in improved food security while protecting environmental resources.

We conducted a systematic review of the published literature on alternative vs. conventional rice production practices, with a focus on alternate wetting–drying and furrow irrigation compared with continuous flooding (the traditional and conventional method of rice production). We examined the evidence for a variety of economic and environmental outcomes, as well as the evidence for arsenic and cadmium uptake in each of these cultivation practices. We also conducted a systematic review of the literature on the impact of tilling vs. no-till agriculture on the concentrations of five agriculturally important mycotoxins—aflatoxins, fumonisins, deoxynivalenol, zearalenone, and ochratoxin A—in a diversity of crops. We compared results across studies for concentrations of these mycotoxins in tilled vs. no-till fields.

Boolean search terms were used to conduct a systematic literature review to identify extractable data sources for summary tables for ACP rice/grain impacts and no-till agriculture/mycotoxin relationships. The review consisted of a systematic and additional examination of relevant sources and citations from these documents for additional references (see refs. 1 , 2 , 3 , 4 , 5 ). Searching took place in Google Scholar and the Michigan State University Library database search tool. The Michigan State University (MSU) Library database search tool allowed for simultaneous searching from multiple databases. The top identified databases where articles were sourced were Complementary Index; Environmental Complete; Academic Search Complete; and Springer Nature Journals. In total, 7 searches took place (reference in Fig. 2 a and b ): (1) alternate wetting–drying cultivation of rice (AWD) and reduced arsenic; (2) furrow irrigation (FI) and reduced arsenic; (3) AWD and yield; (4) FI and yield; (5) AWD and increased cadmium; (6) FI and increased cadmium; and (7) no-till agriculture and mycotoxin occurrence. Peer-reviewed publications from the last 30 years (since 1994) were considered for review for the alternative cultivation practices’ (ACP) impacts. Detailed review of 143 sources allowed for the identification of 28 sources with extractable data. A study is needed to provide synthesizable evidence of ACP compared to conventional cultivation for the desired impact, arsenic/cadmium content, or yield to be included in our review. For the no-till and mycotoxin review, selection criteria were not limited to the last 30 years and the search criteria stipulated peer-reviewed sources.

Panel A shows the selection and inclusion criteria of studies related to rice production methods. Search numbers refer to (1) alternate wetting-drying cultivation of rice (AWD) and reduced arsenic; (2) furrow irrigation (FI) and reduced arsenic; (3) AWD and yield; (4) FI and yield; (5) AWD and increased cadmium; and (6) FI and increased cadmium. 1, 3, and 5 on the left with 159 initial records. The primary search term was “alternate wetting-drying” with secondary terms OR “alternative wetting drying” or “AWD rice”. The number of studies evaluated at each step is included in the boxes. Panel B shows the selection and inclusion criteria of studies related to no-till agriculture and mycotoxin occurrence (Search 7). The primary search term was “no-till agriculture” with secondary “no-till agriculture” or “tillage”. Progresses to 2 records excluded due to language/subject review; leading to 11 records assessed. Right side demonstrates 100 initial records identified with “mycotoxin occurrence” in the title. Secondary terms were “mycotoxin concentration”, “aflatoxin”, “fumonisin”, “deoxynivalenol”, “zearalenone”, or “ochratoxin A”. The number of studies evaluated at each step is included in the boxes.

The systematic inclusion/exclusion process of studies related to rice cultivation practices and diverse effects, and no-till agriculture and mycotoxin risks, can be seen in Fig. 2 a and b , respectively. Our review consisted of extensive consideration of in-text citations and referenced studies drawing from the initial systematic search. However, despite extensive searching, evaluating, and reference-checking, there is a potential for introduced bias in utilizing peer-reviewed publications that are indexed in the MSU database registry and in Google Scholar. By only including indexed, peer-reviewed, and English-language publications, potential alternative perspectives and non-traditional theoretical/methodological approaches may have been excluded from our analysis and presentation of findings.

Data availability

All data generated or analyzed during this study are included in this published article and its references.

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This work was supported by the Institute for the Advancement of Food and Nutrition Sciences (IAFNS) through contract IAFNS-MICHIGANSTATE-20220328; and US Department of Agriculture (USDA) Grant MICL02527. IAFNS is a nonprofit science organization that pools funding from industry collaborators and advances science through in-kind and financial contributions from public and private sector participants. IAFNS and USDA had no role in the design, analysis, interpretation, or presentation of the data and results.

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Impacts of solid waste management strategies in urban high density suburbs: a case of Amaveni suburb, Kwekwe, Zimbabwe

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• Published: 14 August 2024
• Volume 2 , article number  97 , ( 2024 )

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• Chireshe Amato 1 ,
• Steven Jerie 1 ,
• Timothy Vurayayi Mutekwa 1 ,
• Tapiwa Shabani 1 ,
• Takunda Shabani 1 &
• Muyambo Tafadzwa 1  

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Improper solid waste management is one of the causes of environmental and health problems in many cities worldwide. It is in this context that the study aimed to determine the solid waste management strategies used in Amaveni suburbs in Kwekwe, Zimbabwe and assess the health and environmental problems associated with the solid waste management strategies used in Amaveni. Researchers used a mixed method design in which quantitative and qualitative data was collected at the same time. Semi –structured interviews, field observations and questionnaires were used to collect data. The sample comprised 380 Amaveni residents, 3 Kwekwe City employees and one Environmental Management Agency (EMA) official. Qualitative data was analyzed thematically while quantitative data was analyzed using inferential statistics. Open dumping and open burning were the dominant solid waste management strategies in Amaveni. The main health problems identified were cholera and malaria. Air pollution, water pollution and loss of urban beauty were the main environmental problems identified. From the findings it can be concluded that solid waste management strategies used in Amaveni were associated with many health and environmental problems and as a result sustainable solid waste management was proposed.

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1 Introduction

Solid waste management is one of the most challenging environmental issues that urban areas face globally [ 1 , 2 ]. This presents that solid waste management is a problem in developed and developing nations, particularly in high density suburbs in urban areas. The continued population growth in cities, need for goods and services coupled with increased urbanization has resulted in a surge of waste production which pose significant challenges to sustainable development [ 3 , 4 ]. In many urban areas, the volume of solid waste generated overwhelms the waste collection and disposal systems, resulting in adverse environmental and public health outcomes [ 3 , 5 ]. Owing to various anthropogenic activities, generation of solid is projected to rise to 3.4 billion tonnes by 2050 [ 2 ]. Generation of solid waste is increasing in the United Kingdom, Canada, Germany and the United States of America among other developed countries [ 6 , 7 ]. Although solid waste is increasing in developed countries, management of solid waste is more sophisticated due to availability of resources. As a result, application of approaches which support turning waste into useful resources is common, thus limiting the quantity of disposed solid waste. Solid waste management strategies refer to approaches adopted by individuals, governments, organizations and communities to effectively handle and dispose solid waste [ 8 ]. Solid waste management generally encompasses activities encompassing generation, treatment, storage, transportation, waste reduction approaches, disposal as well as monitoring of disposal sites. Reference [ 9 ] argued that solid waste management strategies should include various practices and techniques aimed at minimising the adverse impact of solid waste on the environment and public health. This suggests that management of solid waste, particularly disposal strategies like landfills must take into account demands of sustainability.

Landfilling is a method of solid waste management which involves compacting and covering solid waste with soil [ 10 ]. Reference [ 7 ] argued that out of all the solid waste that the municipalities collect, over 70% is disposed in landfills and dumpsites, 19% is recycled and 11% is utilised for energy recovery. However, studies by [ 11 ] highlighted that 59% of global solid waste is disposed in landfills. In developed countries like Australia and Japan environmental health problems associated with landfilling are low since landfills are equipped with gas and leachate control systems while waste is compacted and covered after disposal [ 12 ]. However, the scenario differs with issues in most developing countries like Zimbabwe, Botswana, Zambia where a number of landfills are operated like open dumpsites [ 5 , 13 , 14 ]. This clearly signifies that in developing countries solid waste is openly dumped on landfills and is not compacted or covered, therefore averting of environmental health risks associated with landfills is difficult. As a result, a number of landfills used in developing countries encompassing Zimbabwe can generate gases like methane which cause air pollution while leachates have potential to reach groundwater since most landfills are unlined. Composting is emerging among significant solid waste disposal approaches in developing and developed regions in the world [ 15 , 16 ]. Organic solid waste including food waste, garden waste and yard waste is disposed through composting since they are biodegradable materials which naturally degrade. In developed countries like France, Sweden and Italy composting is present to be more practical since residents are equipped with enough storage receptacles to practice proper segregation [ 17 ]. Composting enables conversion of biodegradable solid waste into organic manure, thus minimizing the need for synthetic fertilizers [ 18 , 19 ]. Recovery of organic fertilizer from composting is limited by poor waste segregation in Sub-Saharan African countries [ 20 , 21 , 22 ]. Moreover, indiscriminate composting reduces the effectiveness of composting, since decomposition is minimized and the compost acts as breeding sites for various pests and organisms which propel transmission of diseases. This is also articulated by [ 5 , 23 ] that co-disposal of solid waste limits efficiency of composting and effectiveness of incinerators.

An incinerator is a waste treatment facility that uses combustion to convert waste materials into ash, flue gas and heat [ 24 , 25 ]. During the incineration process, solid waste is combusted at high temperatures typically between 850 and 1200 °C which results in the conversion of the organic materials into ash, flue gas and heat [ 18 , 25 , 26 ]. Considering this, incineration Solid waste incineration is a waste treatment process that involves the burning of solid waste in specialised facilities known as incinerators and incineration has the potential to reduce the quantity of solid waste. Incinerators used in development to be more sophisticated since they allow energy to be recovered during incineration [ 27 , 28 ]. In developed nations in Northern America and Europe, utilise incinerators with emission scrubbers and energy recovery systems [ 27 , 28 ]. This suggests that characteristics of incinerators used in developed countries advocate for air pollution reduction while supporting a circular economy. The situation is different in developing countries in Asia and Africa where most of the incinerators are almost of sub-standard since they lack energy recovery and emission control systems [ 29 , 30 ]. Considering their characteristics, it implies that these incinerators have potential to cause various environmental health risks. This reduces the ability of developing countries to meet demands of sustainable development goals namely goal 13 of Climate Action and 3 of good health and well-being. To worsen the scenario, efficiency of incinerators is lessened by utilisation of incinerators with cracked combustion chambers in developing nations like Zimbabwe [ 31 , 32 ]. These incinerators produce partially burned materials and numerous gases and particulate matter namely carbon dioxide, monoxide, Sulphur dioxide, dioxins and furans. This implies that management of solid waste through the incineration process is among factors contributing to high occurrence of respiratory diseases as well as cancer since dioxins and furans are carcinogenic. This is supported by studies which illustrated that incinerators used in other developed and developing countries release pollutants such as dioxins, heavy metals, and particulates which pose health risks to people [ 18 , 33 ]. Exposure to compounds emitted from incinerators may occur by inhalation of contaminated air, consumption of local agricultural produce or contact with contaminated ashes.

Furthermore, in developing countries like Botswana and Namibia collection of solid waste is described as insufficient [ 34 , 35 ]. This goes in line with [ 36 ] that collection of solid waste from point of generation to official disposal sites is approximately 40 to 70% in most developing countries. This is ascribed to shortage of resources particularly finance to purchase enough waste collection trucks, fuel as well as finance to pay workers. In Sub Saharan Africa insufficient solid waste collection by municipalities leave residents with no option but they resort to illegal dumping [ 37 , 38 ]. Illegally disposed solid waste is found along road edges, on open spaces, in drains as well as buildings under construction among other undesignated sites. Continuous accumulation of unmonitored solid waste on these sites result in land, water, soil pollution while acting as breeding sites for mosquitoes, rats, rodents in cities like Masvingo in Zimbabwe [ 39 ], in informal settlements in South Africa [ 40 ] and in cities in Nigeria [ 41 ]. This suggests that disposal of solid waste on non-regulated sites is associated with various forms of pollution, disturbing aesthetic value of the land while accelerating outbreak of intestinal diseases, malaria and rat bite fever. According to [ 39 , 42 , 43 ] besides illegal dumping of solid waste, people always apply open combustion as well as discarding in open pits at household level. Although these methods are of low cost, therefore easy to apply in developing countries [ 23 , 43 , 44 ], open air burning of solid waste releases various toxic gases with potential to manipulate air quality negatively while causing numerous ailments to people. Backyard solid waste burning coupled by use of backyard shallow open pits is highly practiced in Zimbabwe, although solid waste is also buried but at a lower rate.

In Zimbabwe, approximately 90% of solid waste is disposed through landfilling, open dumping, open burning and into open pits although a certain proportion of solid waste is illegally disposed [ 21 , 45 ]. This asserts that application of recycling, reuse, recovery, repair and refurbishment is limited in the Zimbabwean context. This goes in line with [ 32 ] that adoption of solid waste management which supports the circular economy in Zimbabwe is at infancy stage. A view supported by studies which indicated that about 63% of all waste generated in developed countries is recycled while less than 10% of generated waste is recycled in developing countries [ 46 ]. Although recycling advocates turning solid waste into useful resources, in developing countries in Southern Africa like Zimbabwe, non-segregated solid waste is transported and indiscriminately disposed [ 45 , 47 ]. In Zimbabwe, management of solid waste from urban residential areas is highly pinned on the lower base of the waste management hierarchy focusing on landfilling, open dumping and incineration [ 39 , 48 ]. These approaches which are least prioritized by the hierarchy have potential to trigger occurrence of a number of environmental health problems. Thus hindering progress towards attainment of various global Sustainable Development Goals and Zimbabwe Vision 2030 targets particularly those related to environmental protection and human health. Inadequate management of solid waste in Zimbabwean urban suburbs, particularly high density suburbs is attributed to population increase which accelerates generation of solid waste [ 49 , 50 ]. This exceeds the capacity of municipalities which are already struggling due to lack of resources due to economic problems experienced by Zimbabwe since the beginning of twenty-first century. Municipalities responsible for supporting high density suburbs are struggling to offer enough services and Amaveni high density suburb in Kwekwe city is also among residential areas impacted by waste management problems.

The problem at hand revolves around the challenges and consequences associated with solid waste management in densely populated urban areas such as Amaveni. The suburb is among other high densities experiencing high population growth, expansion and infrastructure deterioration translating to difficulties in waste management. The lack of proper waste management infrastructure and practices in this high-density suburb exacerbates challenges experienced by people who are already vulnerable to deteriorating living conditions. This creates a pressing need for sustainable solid waste management approaches tailored to the specific context of high density suburbs. Therefore, in order to deal with the matter meticulously this study focuses on understanding the effects of various solid waste management strategies in an urban high-density suburb, specifically focusing on the Amaveni suburb in Kwekwe, Zimbabwe. Results of the research are essential since they pave route to achieve various environmental health goals advocated for by Sustainable Development Goals (SDGs) namely good health and well-being (3), clean water and sanitation (6), life below water (14), life on land (15), sustainable cities and communities (11), responsible consumption (12) among others, Zimbabwe’s second republic Vision 2030 targets and Agenda 21, Chapter 21 which calls for proper management of waste including solid waste. Moreover, urban high-density suburbs face unique challenges when it comes to waste management due to the concentration of population and limited space [ 49 , 50 ]. Understanding the specific issues faced by these areas such as inadequate infrastructure, limited resources and high waste generation rates is essential for developing targeted interventions. Moreover, the choice of Amaveni suburb in Kwekwe, Zimbabwe as a case study provides valuable insights into the practical implications of waste management strategies in a real world setting. Consequently, by focusing on a specific location, the study can assess the effectiveness of existing strategies, identify local constraints and propose context specific recommendations. Unearthing issues surrounding solid waste management in Amaveni enable the Zimbabwean government to formulate policies directed to management of solid waste in high density suburbs. Findings from this study can serve as a model to develop proper solid waste management for other similar urban areas particularly high density residential areas facing comparable challenges in waste management. In the Zimbabwean context, studies related to impacts of solid waste management always cover whole cities, therefore, in-depth information linked to high density suburbs only is scarce. As a result, besides enabling sustainable management of solid waste, this research also covers the literature gap. The research was guided by objectives namely to assess the current solid waste management practices in the Amaveni suburb, to evaluate the environmental and health impacts of existing waste management strategies and to propose possible recommendations to enhance solid waste management approaches and suppress environmental health problems that emanate from the management techniques.

2 Materials and methods

2.1 location of the study area.

The study area is illustrated in Fig.  1 in Kwekwe town. Kwekwe is a town in the Midlands province of Zimbabwe and has a population of about 119,863. Kwekwe is made up of low, medium and high-density suburbs. Amaveni is one of the high-density suburbs in Kwekwe situated in the northern side of the Kwekwe Central Business District (CBD). A Central Business District (CBD )  is generally a commercial center within a city that typically contains a high concentration of commercial spaces, offices and financial institutions [ 51 , 52 ]. Mostly, large volumes of specialised goods and services are exchanged within the CBD. Amaveni is about 5 km from the CBD. Its geographical coordinates are 18 55 30° south, 29 46 54° east from the CBD. Amaveni is one of the oldest suburbs in Zimbabwe which was established during the colonial era as a racially segregated dormitory for African male laborers. Today Amaveni is made up of people from different professional backgrounds. Amaveni suburb in Kwekwe, Zimbabwe, represents a high-density urban area facing specific challenges related to solid waste management. Therefore, by focusing on this particular suburb, the research can delve deep into the intricacies of waste management strategies within a densely populated urban setting. Utilisation of Amaveni as a case study provides local relevance. Hence, the choice of Amaveni suburb allows the study to address issues that are directly relevant to the local community and policymakers. Understanding the impacts of solid waste management strategies in this specific context can lead to more targeted and effective solutions tailored to the needs of the residents.

Amaveni suburb, Kwekwe, Zimbabwe

2.2 Method of data collection

During the research triangulation method was employed during data collection, analysis and presentation. According to [ 53 ] triangulation refers to research that combines quantitative and qualitative methods within a single study. The mixed-methods approach was suitable for this study as it allowed a deeper understanding of the complexities and nuances of solid waste management practices in residential areas [ 54 ]. By combining qualitative and quantitative data more accurate and contextually rich information is obtained resulting in findings that can be generalized to other settings or populations [ 55 ]. Furthermore, mixed research design enabled the researchers to triangulate quantitative data from questionnaires and qualitative data from semi-structured interviews and observation thereby increasing the validity of the findings [ 56 ].

The target population for this study comprises residents of Amaveni suburb in Kwekwe, Zimbabwe. Amaveni suburb had approximately 2000 houses with a population of around 20,000 people. Cochran’s formula was used to determine sample size:

n = \(\frac{{z}^{2}*p(1-p)}{{e}^{2}}\) where p is standard deviation = 0.5, z is standard normal deviate at 95% confidence interval which is set at 1.96, e is margin of error = 5%

n is sample size

Thus 384 participants took part in this study.

Stratified random sampling was used to select Amaveni residents who took part in the study. Stratified random sampling ensured that a diverse representation of households across different sections of Amaveni were included in the study. It also ensured that there was no bias in the selection of the population sample and every member of Amaveni suburb had an equal chance of being selected. The suburb was sub-divided into 20 sections based on geographical locations. From each section 19 residents were randomly selected thereby having a total of 380 residents. Questionnaires with both open ended and closed ended questions were self-administered to collect data regarding objectives of the study. The questionnaire consists of questions related to demographic data of the respondents, solid waste management strategies including waste disposal methods, environmental health risks associated with existing management strategies as well as possible strategies to minimize impacts of solid waste.

Purposive sampling was used to select three key informants from the Kwekwe city council and one from the Environmental Management Agency. Two council officials from the department of waste management were selected and these included the director of waste management services and one waste collection worker because they had information on solid waste management. One environmental health technician (EHT) from the department of health within the city council was also selected to provide reliable insights on health impacts associated with solid waste management. The EMA official was selected to provide reliable information on environmental impacts associated with solid waste. Interview guides were used to collect data from purposively selected interviewees. The key informants were expected to provide in-depth knowledge related to solid waste management methods, impacts of solid waste on human health and the natural environment. Interviews were also used to solicit data on strategies to curb detrimental impacts that emanate from inadequately managed and disposed solid waste. Furthermore, an observation checklist was prepared and used to collect data during the study, therefore the nature of disposed solid waste, areas with undesignated dumpsites and possible environmental impacts were observed. A digital camera was used to capture images during field observations. Secondary data sources were also used as sources of already existing literature. This assists in understanding the past and current trends in solid waste management strategies and their impacts. Figure  2 presents a brief structure of the research methodology.

A brief structure of the research methodology

2.3 Data analysis and presentation

The collected quantitative data was analyzed using statistical software for social sciences (SPSS) and thematic analysis. Quantitative data obtained from the survey questionnaire was analyzed using descriptive statistics, such as frequencies, percentages, and Chi-square, to identify patterns, trends, and relationships. Qualitative data from interviews and observations was transcribed, coded, and subjected to thematic analysis to identify recurring themes and patterns. The themes used in the description were derived from the research objectives. The themes include solid waste management strategies used in Amaveni, health and environmental impacts associated with solid waste management. Findings of this research were presented on graphs, tables and pie charts for easy interpretation.

2.4 Research ethics

Research ethics play a crucial role in ensuring the integrity and validity of a research study. The research ethics followed during the study plays a vital role in ensuring that research upholds the interests of the public, research subjects and researchers themselves by establishing guidelines for responsible conduct throughout all stages of the research process. Research ethics followed during the study encompass informed consent, confidentiality as well as seeking permission to conduct the study from responsible authorities.

3 Research results

3.1 solid waste management strategies, 3.1.1 bin provision.

All respondents (100%) unanimously reported that the Kwekwe city council is failing to provide enough bins to store household solid waste, hence each household found their own container to store solid waste before collection. Most of the participants used 50 kg sacks (70%), 15% used black polythene bags, 8% had plastic bins, 2% used metal bins and 1% used cardboard boxes to store solid household waste. This was supported by observations which demonstrated that people in Amaveni suburbs used different types of solid waste storage receptacles. This information concurs with information obtained through interviews. Interviewee A revealed that “Kwekwe city council used to provide bins to residents long back; however they have stopped providing bins to residents due to financial constraints.” (Excerpt from interview Kwekwe, 2023).

3.1.2 Waste disposal

A significant number of people who answered questionnaires (52%) dispose their solid waste through open burning while 22% of those who responded dispose waste through open dumping as shown in Fig.  3 . Twenty-five percent of questionnaire respondents dispose waste through land filling and only 1% of waste is recycled.

Waste disposal methods (Fieldwork, 2023)

Interviewee D revealed that:

“Open burning and dumping of solid waste is rampant in Amaveni suburb due to erratic collection of waste by the Kwekwe city council.” (Excerpt from interview, Kwekwe, 2023).

Interviewee C said “Household solid waste collected from Amaveni suburb is landfilled at the outskirts of the suburb however there is a lot of waste dumped in open spaces”. (Excerpt from interview, Kwekwe, 2023).

Observations point out that some waste dumps within the suburb as well as on the unsanitary landfill near the suburb. Observations indicated that solid waste was also disposed on non-designated sites including road sides, open spaces and in drains. Figure  4 is evidence of solid waste dumped on non-designated open space.

Dump waste in Amaveni suburb (Fieldwork, 2023)

3.2 Health impacts

3.2.1 water borne diseases.

Responding to the question on water borne diseases, Interviewee C said:

“Increasing illegal solid waste disposal in Amaveni is posing risks to people’s health as more and more flies breed in the dumpsites increasing the chances of cholera outbreak.”

Interviewee D also revealed that “Dumping of solid waste has polluted water sources in Amaveni and this has increased the risk of cholera in Amaveni suburb.”(Excerpt from interview, Kwekwe, 2023).

Results from interviews were supported by questionnaire respondents since residents indicated that improperly managed waste is facilitating outbreak of water borne diseases namely cholera (64%), typhoid (15%), dysentery and diarrhea (21%).

3.2.2 Vector borne diseases

Interviewee C’s response on the question regarding health risks associated with solid waste management was:

“Mosquitoes are breeding on decomposing solid waste dumped in open spaces increasing the risk of malaria in Amaveni suburb”. (Excerpt from interview, Kwekwe, 2023).

Vectors observed on dumpsites mosquitoes, houseflies, rats and cockroaches. All these have potential to cause vector borne ailments. Questionnaire participants (100%) highlighted that improperly managed solid waste offer breeding sites for vectors with potential to cause vector borne diseases including malaria, sleeping sickness and rat bites fever.

3.2.3 Respiratory diseases

In response to the question relating to respiratory diseases Interviewee C revealed that:

‘Many residents burn solid waste in the suburb which produces a lot of smoke and this has caused many people to experience coughing problems.’(Except from interview, Amaveni suburb, 2023).

Interviewee D shared the same sentiments and said:

“A lot of smoke is produced in the suburb from burning of solid waste and many people are exposed to the risk of breathing the smoke resulting in coughs” (Excerpt from interview, Kwekwe, 2023).

Key informants argued that toxic gases from solid decomposition and open burning cause various respiratory diseases encompassing asthma, tuberculosis, bronchitis and lung cancer. Information from questionnaire participants suggested that existing solid waste management approaches like open burning are associated with tuberculosis (13%), asthma (55%) and persistent coughing (32%) (Fig.  5 ).

Nature of respiratory diseases highlighted by respondents (Fieldwork, 2023)

3.2.4 Injury problems

Responding to a question on injury problems, interviewee C stated that:

“Waste pickers and many waste workers are cut by sharp objects at dump sites” (Excerpt from interview, Kwekwe, 2023).

Interviewee A concurred with the view above and said:

“Waste workers often request for safety shoes and gloves to protect themselves from cuts from broken glass and scrap metal.” (Excerpt from interview, Kwekwe, 2023).

Broken glass, scraps of metal and tins were observed within dumpsites during field observation (Fig.  6 ). Information above confirms that injuries are associated with improper solid waste management in Amaveni suburb. Questionnaire respondents argued that scraps of metal and broken glass are sharp objects; hence, they increase the risk of cuts (82%), pricks (12%) and piercing (6%) among waste scavengers and children who consider illegal dumpsites as playgrounds (Fig.  7 ).

Scraps of metal within unsanitary landfill (Fieldwork, 2023)

Types of injuries caused by sharp waste (Fieldwork, 2023)

3.3 Environmental impacts

3.3.1 air pollution.

Most of the questionnaire respondents (80%) agreed that solid waste strategies used in Amaveni were associated with air pollution, although 15% were not sure while not agreeing was indicated by 5% (Table  1 ). Moreover, during field survey smoke from solid waste open burning was observed at a dumpsite used to dispose solid waste collected from Amaveni suburb (Fig.  8 ).

Burning waste emitting smoke into the air (Fieldwork, 2023)

The information from questionnaires concurred with information obtained through interviews. Interviewee D noted that:

“Air pollution is one environmental risk associated with solid waste management strategies used in Amaveni since burning of solid waste is common” (Excerpt from interview, Kwekwe, 2023).

3.3.2 Water pollution

The majority of people who responded to questionnaire questions (90%) agreed that water pollution was associated with illegal solid waste disposal (Table  1 ). However, 8% of the respondents were not sure while 2% of the questionnaire participants failed to agree. Solid waste was observed in surface water sources as shown by plastics floating on water (Fig.  9 ).

Solid waste in water sources (Fieldwork, 2023)

Information from interviews was in harmony with information obtained through questionnaires. Interviewee D said:

“The streams are clogged with plastics that are being thrown all over in Amaveni suburb” (Excerpt from interview, Kwekwe, 2023).

3.3.3 Loss of urban beauty

The majority of questionnaire participants (86%) agreed that poor solid waste management is associated with loss of urban beauty. Responses from questionnaires were in harmony with interviews. Interviewee D noted that:

“The general outlook of Amaveni suburb is dirty due to illegal dumping of solid waste in open spaces.” (Excerpt from interview, Kwekwe, 2023).

The researchers observed solid waste illegally disposed on open spaces and this has reduced the aesthetic value of Amaveni suburb as shown in Fig.  10 . This means solid waste management strategies used in Amaveni suburb were associated with loss of urban beauty.

Dumpsite near houses making the area lose beauty (Fieldwork, 2023)

4 Discussion

In this study, all questionnaire respondents (100%) unanimously reported that the Kwekwe city council failed to provide bins for storing household solid waste. Consequently, each household had to procure their own containers for solid waste storage before collection, although the city council sometimes provided. Approximately 70% of the study’s participants utilised 50 kg sacks for storing their solid household waste while around 15% opted for black polythene bags. This clearly illustrates that most of the storage receptacles used by residents in this high density suburb are temporary, not durable and can be easily torned by stray dogs. A view upheld by [ 45 ] and [ 57 ] that sometimes receptacles such as plastics and cardboard boxes are torned by dogs before waste collection or by waste collectors during collection. This increases littering in residential areas like Amaveni high density suburbs. In the past, the Kwekwe City Council used to provide bins to residents as part of their waste management services but due to financial constraints, they have made the decision to discontinue this service. This is supported with studies which indicated that currently most of the city councils in Zimbabwe are incapacitated to provide sufficient services to residential areas of their jurisdiction [ 58 , 59 ]. Nevertheless, owing to lack of enough storage receptacles, residents fail to manage their waste effectively from storage to disposal, translating to littering, environmental pollution and public health concerns. This generally points out that lack of adequate resources among responsible city councils is widening the gap to achieve Sustainable Development Goal 11 which advocates for sustainable cities and communities.

This study allows us to understand that various methods are used to dispose of solid waste generated from Amaveni suburb, which conforms with a study by [ 49 ] indicating that solid waste collected from Bulawayo suburbs is discarded through several approaches, namely landfilling, open pits, open dumping, and burning' in the in discussion. Collected data revealed that 52% of the participants opt for open burning as a means of waste disposal, while 45% resort to open dumping. Open burning and open dumping are two common but highly unsustainable methods used to dispose waste from Amaveni. These approaches are less sustainable since burning of solid waste generates various air pollutants with potential to cause serious health risks to vulnerable individuals while adding greenhouse gasses into the atmosphere. Therefore, reliance on open burning among other disposal methods limit the ability of the Zimbabwean government to attain requirements of Sustainable Development Goal 3 and 13 of good health and well-being and climate action respectively. Toxic gases and fumes from solid waste combustion are increasing the prevalence of respiratory diseases, headache and nose irritation among people [ 32 , 60 ]. Similarly, highly used open dumping not only leads to unsightly and unhygienic conditions but also contaminates soil and water sources while impacting both human health. Therefore, besides affecting soil quality, these contaminants hinder achievement of universal and equitable access to safe and affordable water as highlighted by Sustainable Development Goal 6 and Zimbabwe Vision 2030. Results indicated that solid waste was also disposed on non-designated sites including road sides, open spaces and in drains. These results state that while many countries have made progress in increasing their coverage of formal waste management systems, there are still gaps in Zimbabwe since illegal dumping of waste is still common. A view upheld by [ 30 , 47 , 49 ] that attaining proper solid waste disposal in developing countries, particularly those in Southern Africa is difficult due to numerous socio-economic and political challenges.

Results from interviews were supported by questionnaire respondents since residents indicated that improperly managed waste is facilitating outbreak of water borne diseases namely cholera (64%), typhoid (15%), dysentery and diarrhea (21%). This entails that improperly managed waste is a major contributor to the outbreak of waterborne diseases such as cholera, typhoid, dysentery and diarrhea. Mismanagement of solid waste in high density suburbs of Zimbabwe is adding burden to health services which are almost failing to serve their purpose. Zimbabwe always experiences high cholera outbreaks which mostly affects high density suburbs and add burden to hospitals and clinics [ 61 , 62 ]. This suggests the significance of investing in effective waste management systems as key interventions for preventing solid waste related diseases. This is because improper waste management is almost against the Sustainable Development Goal 3, target 3.9 target of reducing the number of illnesses and deaths related to air, water and soil contamination in Zimbabwe. Vectors observed on dumpsites such as mosquitoes, houseflies, rats and cockroaches are significant public health concerns due to their potential to transmit diseases or cause discomfort and injury to humans. These findings tally very well with [ 63 ]’s view in Botswana and Ethiopia that improperly monitored dumpsites act as suitable breeding sites for vectors. The presence of these vectors on dumpsites poses a serious risk to public health as they can spread diseases within communities and contaminate the environment. Questionnaire respondents (100%) highlighted that improperly managed solid waste offer breeding sites for vectors with potential to cause vector borne diseases including malaria, sleeping sickness and rat bites fever. This illustrates that when solid waste is not managed effectively, particularly on disposal sites, it can create environments that attract and support the proliferation of disease carrying vectors. This is supported by [ 43 ] and [ 64 ] that improperly managed solid waste can indeed serve as breeding sites for vectors, which are organisms that can transmit diseases to humans. Proper methods to spray and control breeding of vectors at designated and non-designated disposal is crucial to safeguard health of people especially those who reside in areas which are less than 500 m from disposal sites.

Key informants supported by questionnaire participants suggested that existing solid waste management approaches like open burning are associated with tuberculosis, asthma and persistent coughing. The evidence presented the detrimental impact of burning solid waste on respiratory health in suburban areas. The findings correspond very well with [ 39 ] that toxic gasses from solid waste burning and decomposition increase prevalence of respiratory diseases among people. Furthermore, the majority (82%) identified cuts as a common type of injury resulting from sharp objects in dumpsites, followed by pricks (12%) and piercing (6%). The sharp edges of broken glass and metal pieces can easily cause injuries when handled or stepped on, leading to various types of wounds such as cuts, pricks and piercing [ 5 , 30 ]. The presence of broken glass, scraps of metal, and other sharp objects in dumpsites within Amaveni suburb poses a serious threat to the health and safety of waste scavengers and children. As waste pickers and workers scavenge through these piles of garbage to collect recyclable materials or items of value, they are exposed to the danger of getting cut by these sharp objects. The lack of proper protective gear like boots, gloves and safety measures further increases the risk for waste pickers and workers to sharp injuries which expose them to tetanus, Hepatitis as well as HIV and AIDS. Similarly, in Latin America and Sudan apart from the immediate pain and discomfort caused by cuts and lacerations, there is also a risk of infection due to exposure to contaminated sharp materials [ 65 , 66 ].

In the context provided, it is evident that there is a concern regarding the association between solid waste strategies in Amaveni and air pollution. The questionnaire results indicate that a significant majority of respondents, 80%, agreed that the solid waste management strategies employed in Amaveni are linked to air pollution. This suggests a widespread perception among the community that the management of solid waste in the area has implications for air quality. Furthermore, during a field survey, smoke from open burning of solid waste was observed at a dumpsite where solid waste collected from the Amaveni suburb is disposed. Less sustainable waste management practices including open air burning leads to air pollution through the release of harmful emissions into the atmosphere [ 4 , 19 ]. This implies that when materials such as paper, cardboard, plastics, textile waste and electronic waste are burned they release pollutants like particulate matter, carbon monoxide and volatile organic compounds into the air. These pollutants have detrimental effects on human health and the environment since particulate matter emitted from open burning can penetrate deep into the lungs and cause respiratory issues [ 44 , 67 ]. Carbon monoxide interferes with the blood’s ability to carry oxygen potentially causing headaches, dizziness and in severe cases, death while volatile organic compounds can harm lung function and aggravate respiratory diseases [ 68 , 69 ]. This signifies the importance of resorting to other solid waste disposal since open burning is cheap while capable of reducing the volume of waste but it speeds up lives of people to graves. In the study conducted in Kwekwe, it was found that a significant majority of questionnaire respondents, amounting to 86%, agreed that poor solid waste management is directly linked to the loss of urban beauty. This sentiment was further reinforced by insights gathered from interviews and observations. This simply highlights that the presence of illegally disposed solid waste in open areas not only poses environmental and health hazards but also significantly diminishes the aesthetic appeal of urban spaces. In the case of Amaveni suburb, the inadequacies in waste disposal mechanisms have directly contributed to a decline in the visual attractiveness of the area. According to [ 70 , 71 ] ineffective solid waste management strategies are among aspects which disturbs urban aesthetics in Kenya. Addressing various environmental health problems that emanate from improperly managed solid waste from Amaveni is paramount in the efforts towards achieving Sustainable Development Goals, and Zimbabwe Vision 2030 targets.

5 Conclusion

Solid waste management is a critical issue in urban high-density suburbs due to the large population concentration, poor infrastructure and limited space for waste disposal. The problem is more pervasive in high density suburbs of developing countries since most of the municipalities responsible to offer services are almost incapacitated. Therefore, this study put much emphasis on impacts of solid waste management strategies in urban high density suburbs: a case of Amaveni suburb, Kwekwe, Zimbabwe”. The research was guided by objectives namely to assess the current solid waste management practices, to evaluate the environmental and health impacts of existing waste management strategies and propose possible recommendations to suppress environmental health problems. This paper has examined various solid waste management strategies utilised in Amaveni high density suburbs and their impacts on human health as well as the environment. Management of solid waste in Amaveni is characterized by a traditional linear approach where solid waste is generated, indiscriminately stored, transported and finally disposed. Solid waste was disposed through open burning, illegal dumping and unsanitary landfilling. Insignificant amount of waste was composted and recycled. Findings illustrated that most of the existing management approaches offer little attention to aspects which support circular economy and the upper part of the waste management hierarchy. Consequently, a large proportion of solid waste is disposed, thus adding pressure to poorly monitored dump sites. Moreover, in order to free solid waste receptacles, residents resort to illegal solid waste disposal along road verges, drains, open spaces and backyard dumping. Verdicts of the study illustrated that improperly dumped solid waste and monitored dumpsites act as breeding sites for pests, vermin and pathogens which trigger occurrence of various health problems. Diseases such as cholera and malaria were health problems identified in Amaveni suburb. The main environmental problems identified included air pollution, water pollution and loss of urban beauty. Solid waste management in Amaveni was far from sustainable since it failed to promote Sustainable Development Goal 3 of good health and wellbeing and Sustainable Development Goal 6 of clean water and sanitation. Existing solid waste management strategies in Amaveni suburb reduce the capacity of Zimbabwe to reach demands of National Development Strategy 1 goals particularly those related to environmental protection while safeguarding human health. The impacts of solid waste management strategies in urban high density suburbs are multifaceted and are presenting far-reaching detrimental impacts to the environment and people. Therefore, effective waste management is essential for preserving the environment, safeguarding public health and promoting sustainable development in these densely populated areas.

6 Study limitations

One significant limitation is the narrow scope of the study since it solely focuses on the Amaveni suburb in Kwekwe. While this specificity allows for an in-depth analysis of a particular area, it limits the generalisability of the findings to other urban high-density suburbs in Zimbabwe or different regions with distinct socio-economic and infrastructural characteristics. Research on solid waste management often faces challenges related to data collection. In this case, limitations may arise from inaccurate or incomplete data provided by interviewees or residents. Another common limitation in the research project may be ascribed to resource constraints. Lack of adequate finance, time constraints and access to necessary equipment may hinder the researchers’ ability to conduct comprehensive fieldwork or analyse data effectively translating to proposing of recommendations with various gaps. However, to minimize limitations of the study various data collection and analysis tools were utilised while secondary data was also used to support the findings.

7 Recommendations

Analysis of the findings demonstrates almost enough evidence which illustrates that impacts of solid waste in Amaveni high density suburbs require attention. The city council should provide enough bins to promote segregation of waste at source. This minimizes transportation and disposal of non-segregated solid waste. Source separation, which is generally a practice of separating waste at its source before it is collected, facilitates easy application of recycling, composting and reuse approaches at household level. Segregation of solid waste minimizes challenges experienced during application of waste reduction approaches in Asian cities [ 72 ]. Promoting waste reduction initiatives which support a circular economy minimize the quantity of disposed solid waste, thus lessening the burden of monitoring disposal sites as well as environmental health problems that emanate from improperly managed dumpsites. Households in Amaveni suburb must be educated and encouraged to compost organic waste. This reduces the quantity of organic waste destined in landfills, therefore lowering greenhouse gasses emissions released into the atmosphere. Composting is among effective solid waste management approaches in Bangladesh [ 73 , 74 ]. Additionally, there is a need to adopt public–private partnership in solid waste management. Public–private partnerships have the potential to facilitate sharing of resources and expertise of both public and private sectors to effectively manage solid waste and construct properly engineered dumpsites. This implies that the city council must collaborate with residents, non-governmental organizations, research institutes and the Environmental Management Agency in suppressing environmental health problems associated with solid waste. The city council, Environmental Management Agency and Zimbabwe Republic Police should work hand in hand to deal with individuals, industries, business among other stakeholders who violate solid waste management legal framework and standards. This improves compliance to recommended standards, translating to reduction of illegally dumped solid waste, thus reducing cropping of diseases linked to inappropriately dumped waste. Additionally, residents should be encouraged by city council and Environmental Management to participate in community initiatives which support clean-up campaigns, recycling, refurbishment, repairing and reuse programs. In order to inject a sense of circular economy in residents, awareness campaigns and training must be conducted by private and public sectors. Most importantly, the city council responsible for offering waste management services to Amaveni suburb must adopt an integrated solid waste management system. Integrated approach presented to be effective in managing solid some parts of India [ 75 ]. Integrated solid waste management systems combine various techniques such as source separation, recycling, composting, landfilling and energy recovery to effectively manage solid waste in a sustainable manner. Such systems can help to reduce the negative impacts of solid waste management on the environment while also providing economic benefits through resource recovery and energy generation. Furthermore, the Government of Zimbabwe must channel enough resources to city councils so that they pin advanced technologies in management of solid waste. Advanced technologies such as anaerobic digestion, gasification, pyrolysis and gasification support conversion of waste into valuable resources such as energy, fertilizer among other resources. These technologies assist to reduce the amount of waste that ends up in landfills or incinerators, thereby reducing the environmental impact. Application of advanced technologies in solid waste management demonstrated to be effective in countries like Canada [ 76 ].

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Amato, C., Jerie, S., Mutekwa, T.V. et al. Impacts of solid waste management strategies in urban high density suburbs: a case of Amaveni suburb, Kwekwe, Zimbabwe. Discov Environ 2 , 97 (2024). https://doi.org/10.1007/s44274-024-00118-1

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“Air pollution in Delhi: Its Magnitude and Effects on Health”

Centre for Community Medicine, All India Institute of Medical Sciences, New Delhi, India

Baridalyne Nongkynrih

Sanjeev kumar gupta.

Air pollution is responsible for many health problems in the urban areas. Of late, the air pollution status in Delhi has undergone many changes in terms of the levels of pollutants and the control measures taken to reduce them. This paper provides an evidence-based insight into the status of air pollution in Delhi and its effects on health and control measures instituted. The urban air database released by the World Health Organization in September 2011 reported that Delhi has exceeded the maximum PM10 limit by almost 10-times at 198 μ g/m3. Vehicular emissions and industrial activities were found to be associated with indoor as well as outdoor air pollution in Delhi. Studies on air pollution and mortality from Delhi found that all-natural-cause mortality and morbidity increased with increased air pollution. Delhi has taken several steps to reduce the level of air pollution in the city during the last 10 years. However, more still needs to be done to further reduce the levels of air pollution.

Pollution refers to the contamination of the earth's environment with materials that interfere with human health, quality of life or the natural functioning of the ecosystems. The major forms of pollution include water pollution, air pollution, noise pollution and soil contamination. Other less-recognised forms include thermal pollution and radioactive hazards. It is difficult to hold any one particular form responsible for maximum risk to health; however, air and water pollution appear to be responsible for a large proportion of pollution related health problems.

Of late, the air pollution status in Delhi has undergone many changes in terms of the levels of pollutants and the control measures taken to reduce them. This paper provides an evidence-based insight into the status of air pollution in Delhi and its effects on health and control measures instituted.

Status of Air Pollution in Delhi

Delhi (or the National Capital Territory of Delhi), is jointly administered by the central and state governments. It accommodates nearly 167.5 lakh people (2011 Census of India).( 1 )

Metros across the world bear the major brunt of environmental pollution; likewise, Delhi is at the receiving end in India.

A study funded by the World Bank Development Research Group was carried out in 1991-1994 to study the effects of air pollution.( 2 ) During the study period, the average total suspended particulate (TSP) level in Delhi was approximately five-times the World Health Organization's annual average standard. Furthermore, the total suspended particulate levels in Delhi during this time period exceeded the World Health Organization's 24-h standard on 97% of all days on which readings were taken. The study concluded that the impact of particulate matter on total non-trauma deaths in Delhi was smaller than the effects found in the United States of America, but found that a death associated with air pollution in Delhi caused more life-years to be lost because these deaths were occurring at a younger age.

A report by the Ministry of Environment and Forests, India, in 1997 reviewed the environmental situation in Delhi over concerns of deteriorating conditions.( 3 ) Air pollution was one of the areas of concern identified in this study. It was estimated that about 3000 metric tons of air pollutants were emitted every day in Delhi, with a major contribution from vehicular pollution (67%), followed by coal-based thermal power plants (12%). There was a rising trend from 1989 to 1997 as monitored by the Central Pollution Control Board (CPCB). The concentrations of carbon monoxide from vehicular emissions in 1996 showed an increase of 92% over the values observed in 1989, consequent upon the increase in vehicular population. The particulate lead concentrations appeared to be in control; this was attributable to the de-leading of petrol and restrictions on lead-handling industrial units. Delhi has the highest cluster of small-scale industries in India that contribute to 12% of air pollutants along with other industrial units.

Vehicular pollution is an important contributor to air pollution in Delhi. According to the Department of Transport, Government of National Capital Territory of Delhi, vehicular population is estimated at more than 3.4 million, reaching here at a growth rate of 7% per annum. Although this segment contributes to two-thirds of the air pollution, there has been a palpable decline compared to the 1995-1996 levels.

The PM 10 standard is generally used to measure air quality. The PM 10 standard includes particles with a diameter of 10 μm or less (0.0004 inches or one-seventh the width of a human hair). These small particles are likely to be responsible for adverse health effects because of their ability to reach the lower regions of the respiratory tract. According to the Air Quality Guideline by the World Health Organization, the annual mean concentration recommended for PM 10 was 20 μg/m 3 , beyond which the risk for cardiopulmonary health effects are seen to increase.( 4 ) Major concerns for human health from exposure to PM 10 include effects on breathing and respiratory systems, damage to lung tissue, cancer and premature death. Elderly persons, children and people with chronic lung disease, influenza or asthma are especially sensitive to the effects of particulate matter. The urban air database released by the World Health Organization in September 2011 reported that Delhi has exceeded the maximum PM 10 limit by almost 10-times at 198 μg/m 3 , trailing in the third position after Ludhiana and Kanpur.( 5 ) Vehicular emissions and industrial activities were found to be associated with indoor as well as outdoor air pollution in Delhi [ Table 1 ].( 6 – 9 )

Air pollutants in Delhi

Effects of Air Pollution on Health

A large number of studies in Delhi have examined the effect of air pollution on respiratory functions and the associated morbidity. The most comprehensive study among them was the one conducted by the Central Pollution Control Board in 2008, which identified significant associations with all relevant adverse health outcomes.( 10 ) The findings were compared with a rural control population in West Bengal. It was found that Delhi had 1.7-times higher prevalence of respiratory symptoms (in the past 3 months) compared with rural controls ( P < 0.001); the odds ratio of upper respiratory symptoms in the past 3 months in Delhi was 1.59 (95% CI 1.32-1.91) and for lower respiratory symptoms (dry cough,wheeze, breathlessness, chest discomfort) was 1.67 (95% CI 1.32-1.93). Prevalence of current asthma (in the last 12 months) and physician-diagnosed asthma among the participants of Delhi was significantly higher than in controls. Lung function was reduced in 40.3% individuals of Delhi compared with 20.1% in the control group. Delhi showed a statistically significant ( P < 0.05) increased prevalence of restrictive (22.5% vs. 11.4% in control), obstructive (10.7% vs. 6.6%) as well as combined (both obstructive and restrictive) type of lung functions deficits (7.1% vs. 2.0%). Metaplasia and dysplasia of airway epithelial cells were more frequent in Delhi, and Delhi had the greater prevalence of several cytological changes in sputum. Besides these, non-respiratory effects were also seen to be more in Delhi than in rural controls. The prevalence of hypertension was 36% in Delhi against 9.5% in the controls, which was found to be positively correlated with respirable suspended particulate matter (PM 10 ) level in ambient air. Delhi had significantly higher levels of chronic headache, eye irritation and skin irritation.

Several other community-based studies have found that air pollution is associated with respiratory morbidity.( 11 – 13 ) Numerous studies have reported an association between indoor air pollution and respiratory morbidity.( 14 – 19 )Some of these studies have concentrated on children's respiratory morbidity.( 15 , 17 , 19 ) Other studies in children have found similar correlations between particulate matter in ambient air and attention-deficit hyperactivity disorder( 20 ) between vehicular air pollution and increased blood levels of lead (a potential risk factor for abnormal mental development in children)( 21 ) and between decreased serum concentration of vitamin D metabolites and lower mean haze score (a proxy measure for ultraviolet-B radiation reaching the ground).( 22 )

Studies that have examined the compounding effect of meteorological conditions on air pollution found that winter worsened the air quality of both indoor air and outdoor air. They also found a positive correlation between the winter weather and rise in the number of patients with chronic obstructive airway disease in hospitals.( 12 , 16 )

There was a relative paucity of studies that measured outdoor air pollutant levels first hand and then tried to objectively correlate them to adverse health effects. However, some studies measured air pollutant levels and found a correlation with health-related events.( 17 , 19 )

A time-series study on air pollution and mortality from Delhi found that all-natural-cause mortality increased with increased air pollution.( 23 ) In another study, gaseous pollutants, in spite of being at a level lower than the permissible level, showed more consistent association with respiratory admissions.( 24 ) In a hospital-based study, an increase in emergency room visits for asthma, chronic obstructive airway disease and acute coronary events was reported with an increase in air pollutant levels.( 25 ) These studies are summarized in Table 2 .

Effects of air pollution in Delhi on health

Control Measures Instituted by the Government of Delhi

The nodal ministry for protecting the environment is the Ministry of Environment and Forests at the Centre and the Department of Environment of the Government of National Capital Territory of Delhi. The Central Pollution Control Board set up in 1974 under the Water Act is the principal watchdog for carrying out the functions stated in the environmental acts, implementation of National Air Quality Monitoring Programme and other activities. The Delhi Pollution Control Board is the body responsible at the state level.

From time to time, the judiciary has taken strong note of the deteriorating environmental conditions in Delhi in response to public litigations. One of the earliest such instances was the judgement passed by the Supreme Court of India to deal with the acute problem of vehicular pollution in Delhi in response to a writ petition filed in 1985. Subsequently, it ordered the shutdown of hazardous, noxious industries and hot-mix plants and brick kilns operating in Delhi.

Vehicular Policy

Control measures so far instituted include introduction of unleaded petrol (1998), catalytic converter in passenger cars (1995), reduction of sulfur content in diesel (2000) and reduction of benzene content in fuels (2000). Others include construction of flyovers and subways for smooth traffic flow, introduction of Metro rail and CNG for commercial transport vehicles (buses, taxis, auto rickshaws), phasing out of very old commercial vehicles, introduction of mandatory “Pollution Under Control” certificate with 3-month validity and stringent enforcement of emission norms complying with Bharat Stage II/Euro-II or higher emission norms. Introduction of The Air Ambience Fund levied from diesel sales and setting up of stringent emission norms for industries and thermal power stations are the other measures. Environmental awareness campaigns are also carried out at regular intervals. The Delhi Pollution Control Board conducts monthly Ambient Air Quality Monitoring at 40 locations in Delhi, and takes corrective action wherever necessary.

Industrial Policy

The first Industrial Policy for Delhi was introduced in 1982. Subsequently, a second Industrial policy (2010–2021) was issued by the Department of Industries, Government of Delhi. It is a comprehensive document envisioning higher industrial development in Delhi, with one of its mandates being to develop clean and non-polluting industries and details of steps to be undertaken in this direction have been described.

There are many other organizations that work synergistically with the government efforts to reduce air pollution. These include the Centre for Science and Environment and The Energy and Resources Institute, and the Indian Association for Air Pollution Control. Representatives of the industries include Confederation of Indian Industry and Society of Indian Automobile Manufacturers. Government agencies like Factories Inspectorate are also involved in the control of pollution. Research and academic institutions include National Environmental Engineering Research Institute, Indian Institute of Technology, Council of Scientific and Industrial Research institutions, Indian Agricultural Research Institute and various other academic institutions in and around Delhi. Professional organizations like the Indian National Science Academy, the Indian Institute of Chemical Engineers and the Indian Institute of Engineers are also involved in pollution control.

Benefits Accrued as a Result of Control Measures

Since the first act on pollution was instituted, huge progress has been made in terms of human resource, infrastructure development and research capability. Some studies tried to gather evidence for the effectiveness of control measures by comparing pre- and post-intervention health status. The study conducted by the Central Pollution Control Board demonstrated that spending 8-10 h in clean indoor environment can reduce health effects of exposure to chronic air pollution.( 10 ) A recent study found significant improvement in the respiratory health following large-scale government initiatives to control air pollution.( 26 ) It was reported that use of lower-emission motor vehicles resulted in a significant gain in disability-adjusted life-years in Delhi.( 27 ) Another study found significant evidence for reduction in respiratory illness following introduction of control measures.( 24 )

Most of the studies were ecological correlation studies, which are severely limited in their ability to draw causal inferences. But, considering the context that demanded the research, these were probably the best available designs to produce preliminary and,sometimes, policy-influencing evidences, as any other methodology would be unethical or operationally impossible.

The Government of National Capital Territory of Delhi has taken several steps to reduce the level of air pollution in the city during the last 10 years. The benefits of air pollution control measures are showing in the readings. However, more still needs to be done to further reduce the levels of air pollution. The already existing measures need to be strengthened and magnified to a larger scale. The governmental efforts alone are not enough. Participation of the community is crucial in order to make a palpable effect in the reduction of pollution. The use of public transport needs to be promoted. The use of Metro rail can be encouraged by provision of an adequate number of feeder buses at Metro stations that ply with the desired frequency. More frequent checking of Pollution Under Control Certificates needs to be undertaken by the civic authorities to ensure that vehicles are emitting gases within permissible norms. People need to be educated to switch-off their vehicles when waiting at traffic intersections. Moreover, the “upstream” factors responsible for pollution also need to be addressed. The ever-increasing influx of migrants can be reduced by developing and creating job opportunities in the peripheral and suburban areas, and thus prevent further congestion of the already-choked capital city of Delhi.

Health, as we all know, is an all-pervasive subject, lying not only within the domains of the health department but with all those involved in human development. Many great scholars from Charaka to Hippocrates have stressed the importance of environment in the health of the individual. Therefore, all those who play a role in modifying the environment in any way, for whatever reason, need to contribute to safeguard people's health by controlling all those factors which affect it.

Source of Support: Nil

Conflict of Interest: None declared.

Water, air emissions, and cost impacts of air-cooled microturbines for combined cooling, heating and power (CCHP) systems: A case study of in the Atlanta region

Case Study Questions Class 8 Science Pollution of Air and Water

Case study questions class 8 science chapter 18 pollution of air and water.

CBSE Class 8 Case Study Questions Science Pollution of Air and Water. Important Case Study Questions for Class 8 Board Exam Students. Here we have arranged some Important Case Base Questions for students who are searching for Paragraph Based Questions Pollution of Air and Water.

CBSE Case Study Questions Class 8 Science Pollution of Air and Water

Case study 1.

Que. 1) Which among the following air pollutants reduces the oxygen carrying capacity of the blood?

(b) Carbon monoxide

(a) Nitrogen dioxide

Que. 2) (d) Chlorofluorocarbons

Que. 3) (b) Smog

Case study 2

Que. 1) The phenomenon of acid rain corroding the monuments made up of marbles is known as ……………………………………………………………………………………… .

(c) Marble cancer

(a) Carbon dioxide

(b) Methane

Case study 3

Que. 1) Majority of people living in regions which are threatened by global warming are in ……………………………………………………………………………………………… .

(d) Antarctica

Que. 4) What is “Van Mahotsav”?

Que. 4) Answer: Van Mahotsav is celebrated in the month of July every year, when lakhs of trees are planted. Planting large amounts of trees can help reduce the amount of carbon dioxide from the environment.

Case study 4

Que. 1) Government of India launched which of the following initiative in 2016 for the purpose of cleaning river ganga?

(d) Zooplanktons

(c) Industries should stop working.

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Evaluation of lora network performance for water quality monitoring systems.

1. Introduction

2. materials and methods, 2.1. water quality monitoring system built, 2.2. study setting, 2.3. lora gateway configuration, 2.4. water quality monitoring dashboard, 2.5. evaluation of lora performance, 3. results and discussion, 3.1. water quality data, 3.2. lora network performance, 3.2.1. rssi and snr, 3.2.2. packet loss, 3.2.3. path loss, 3.2.4. received power, 4. conclusions, author contributions, institutional review board statement, informed consent statement, data availability statement, acknowledgments, conflicts of interest.

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Share and Cite

Syed Taha, S.N.; Abu Talip, M.S.; Mohamad, M.; Azizul Hasan, Z.H.; Tengku Mohmed Noor Izam, T.F. Evaluation of LoRa Network Performance for Water Quality Monitoring Systems. Appl. Sci. 2024 , 14 , 7136. https://doi.org/10.3390/app14167136

Syed Taha SN, Abu Talip MS, Mohamad M, Azizul Hasan ZH, Tengku Mohmed Noor Izam TF. Evaluation of LoRa Network Performance for Water Quality Monitoring Systems. Applied Sciences . 2024; 14(16):7136. https://doi.org/10.3390/app14167136

Syed Taha, Syarifah Nabilah, Mohamad Sofian Abu Talip, Mahazani Mohamad, Zati Hakim Azizul Hasan, and Tengku Faiz Tengku Mohmed Noor Izam. 2024. "Evaluation of LoRa Network Performance for Water Quality Monitoring Systems" Applied Sciences 14, no. 16: 7136. https://doi.org/10.3390/app14167136

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