Unequal Pollution Extremes Across the World: A Deep Learning Assessment (1980–2023)
npj Climate and Atmospheric Science (Nature Portfolio), 2025
Authors: Kuldeep Singh Rautela, Manish Kumar Goyal, Ajay Singh Nagpure
Collaborative Institution: Indian Institute of Technology (IIT) Indore
Sector: Climate Analytics | Air Quality Extremes | AI-Based Modeling
What This Study Examined
Fine particulate matter (PM₂.₅) is one of the most harmful air pollutants affecting global health. While average pollution levels are widely studied, extreme pollution events—when concentrations spike to hazardous levels—remain less understood.
This study analyzed daily PM₂.₅ concentrations from 1980 to 2023 using advanced deep learning models combined with meteorological data. The estimates were validated against the World Health Organization (WHO) ambient air quality database to ensure reliability.
What Makes This Study Distinct
- Applied ensemble artificial intelligence models (CNN, LSTM, DNN)
- Assessed pollution extremes rather than long-term averages alone
- Used population-weighted metrics to reflect real exposure risk
- Examined more than four decades of global air quality trends
Key Findings
- China, India, and Pakistan continue to experience persistently high pollution extremes
- Europe and North America show measurable declines in extreme exposure
- Strong seasonal variability was observed across several African regions
- Nearly 80% of the global population lives in areas exceeding USEPA annual PM₂.₅ standards
- Approximately two-thirds of global land area exceeds recommended air quality thresholds
Why It Matters
Extreme pollution episodes pose significant short- and long-term health risks, particularly in densely populated and economically vulnerable regions. By identifying where and when these extremes occur, this study supports phased, locally adaptive air quality strategies tailored to regional conditions.
Read the full article: https://doi.org/10.1038/s41612-025-01183-w
Why City Clean-Air Plans Need Regional Action: Transboundary PM₂.₅ in Indian Cities
Environmental Research Letters (IOP Publishing), 2025 • Volume 20(5), 054008 • Open Access
Authors: Raj M. Lal, Ajay S. Nagpure, Abhinav Anand, Sujit Maji, Kushal Tibrewal, Ganesh Gupta, Chandra Venkataraman, Kangkang Tong
Collaborative Institution: Indian Institute of Technology (IIT) Bombay (NCAP-COALESCE / SMoG-India)
Sector: Transboundary Air Pollution | Clean Air Policy | Emissions Systems Modeling
What This Study Examined
India’s National Clean Air Programme (NCAP) set targets to reduce PM₂.₅ in 122 cities, but air pollution does not stop at city boundaries. This study tested a core question: How much of a city’s PM₂.₅ is coming from outside the city?
What WEN and Collaborators Did
The study assessed 143 Indian cities using two complementary approaches and a new national emissions dataset:
- Combined top-down atmospheric transport (STILT-PM₂.₅) and bottom-up chemical transport modeling (WRF-Chem)
- Used a nationwide, monthly, fine-scale (5 km × 5 km) anthropogenic emissions inventory (SMoG-India)
- Estimated how much PM₂.₅ in each city originates inside versus outside the urban boundary
- Identified which sectors drive the outside-city contribution
Key Findings (Plain Language)
- On average, ~85% of PM₂.₅ in these cities is coming from outside city limits
- The largest outside-city contributors are:
- Domestic biomass burning (~32%)
- Energy generation (~16%)
- Industry (~15%)
- For 107 of 122 NCAP cities, outside-city contributions exceed 80%, meaning even perfect in-city control would not meet NCAP targets for most cities
- Big metros (e.g., Delhi, Mumbai, Kolkata, Bengaluru) have lower transboundary shares than smaller cities—but transboundary pollution is still substantial
Why It Matters for Policy
Most city plans focus on within-boundary actions (traffic management, dust control, local industry). This paper shows that for most Indian cities, regional emissions dominate, so clean air targets require multi-scale planning—city actions plus coordinated regional strategies addressing household energy, power generation, and industrial corridors outside city limits.
Read the full open-access article (DOI): https://doi.org/10.1088/1748-9326/adc147
Bioenergy from Livestock Waste and Crop Residue: District-Level Potential Across Rural India (602 Districts)
Science of the Total Environment (Elsevier), 2023 • Volume 889, 163974
Authors: Ritesh Kumar, Vivek Kumar, Ajay Singh Nagpure
Collaborative Institution: Indian Institute of Technology (IIT) Delhi
Sector: Bioenergy | Clean Cooking | Rural Energy Systems | Air Pollution Reduction
What This Study Examined
Rural India still relies heavily on cow dung and crop residue for cooking—driving household air pollution and contributing to severe outdoor pollution when residues are burned in the open. This study answers a practical policy question: how much clean cooking energy could India generate locally if livestock waste and surplus crop residue were converted into biogas?
What WEN and Collaborators Did
The research conducted the first district-scale assessment across 602 rural districts to estimate:
- Rural cooking energy demand
- Biogas energy potential from livestock waste
- Biogas energy potential from surplus crop residue
- Combined potential and the associated PM₂.₅ reduction under different scenarios
Key Findings (Plain Language)
- Rural India needs ~1927 TJ/day of cooking energy (about 2.75 MJ per person per day)
- Livestock waste alone could supply ~37% of rural cooking energy demand
- Surplus crop residue alone could supply ~100% of rural cooking energy demand at the national level (if locally captured and utilized)
- 39% of districts could meet 100% of cooking energy demand using surplus crop residue alone
- Combining livestock waste + surplus residue could exceed 100% of cooking demand in ~56% of districts
- Converting agricultural waste into clean energy could reduce PM₂.₅ emissions by ~33% to 85%, depending on the scenario
Why It Matters
This study reframes “waste” as a local energy resource. It shows that district-level planning for biogas can simultaneously address: clean cooking access, rural energy poverty, crop residue burning, and PM₂.₅ reduction—with strong co-benefits for health and climate resilience.
Read the full article (DOI): https://doi.org/10.1016/j.scitotenv.2023.163974
High-Resolution PM₂.₅ Emissions and Health Inequalities in Saharanpur District, India
Environmental Science & Technology, 2023 | Volume 57, Issue 6
Authors: Gaurav Tomar, Ajay Singh Nagpure, Yash Jain, Vivek Kumar
Collaborative Institution: Indian Institute of Technology (IIT) Delhi
Sector: Air Pollution | Public Health | Environmental Inequality | Micro-Level Emissions
What This Study Examined
Air pollution does not affect everyone equally. This study investigated how fine-scale emissions within a single Indian district (Saharanpur) translate into unequal health burdens across urban and rural populations—especially among low socioeconomic groups.
What WEN and Collaborators Did
The research developed micro-level emission estimates for key infrastructure sectors in both urban and rural areas and linked them with pollutant transport analysis to quantify health impacts.
The study calculated:
- Surface PM₂.₅ concentrations
- Premature mortality
- Disability-Adjusted Life Years (DALYs)
- Exposure disparities across socioeconomic groups
Key Findings (Plain Language)
- Urban premature deaths: 158 per 100,000 people
- Rural premature deaths: 143 per 100,000 people
- Total annual premature deaths: ~6,372 deaths
- 68% of total deaths occurred in rural areas, despite weaker monitoring presence
Inequality Findings
Compared to their share of emissions, low socioeconomic groups experienced higher health burdens:
- Transportation: 26% higher premature deaths relative to contribution
- Household cooking fuel burning: 7% higher
- Open waste burning: 7% higher
- Industry: 6% higher
Most DALYs were concentrated among economically vulnerable worker groups. Because many rely on daily wages, loss of healthy life years directly impacts income and livelihood stability.
Why It Matters
This study shows that air pollution is both an environmental and social equity issue. High-resolution emissions data reveals hidden disparities that broader national inventories often miss.
The findings call for:
- Micro-level pollution mitigation
- Targeted protection for vulnerable groups
- Equity-centered clean air policies
Read the full article: https://pubs.acs.org/doi/10.1021/acs.est.2c05636
PM₂.₅ Exposure Increased During COVID-19 Lockdowns: A Residential Biomass Burning Perspective
Environmental Research Letters (2022) | Open Access
Authors: Ajay S. Nagpure, Raj M. Lal
Sector: Household Air Pollution | Environmental Justice | Exposure Science | Clean Cooking
What This Study Asked
During COVID-19 lockdowns, outdoor air became cleaner in many cities worldwide.
But what happened inside homes where biomass is used for cooking?
This study examined whether lockdowns actually increased PM₂.₅ exposure for populations relying on residential biomass fuels.
What the Study Did
- Combined nationwide time-use survey data from India
- Integrated fine-scale PM₂.₅ estimates across different indoor and outdoor microenvironments
- Compared baseline (pre-lockdown) exposures with lockdown exposures
- Extended the framework to estimate global impacts
Key Findings in India
- 65% of Indians (those using biomass for cooking) experienced higher PM₂.₅ exposure during lockdown
- Average exposure increased 13%
- From 116 µg/m³ (baseline)
- To 131 µg/m³ (during lockdown)
Exposure Inequality
- Women continued to experience the highest exposure levels overall
- The largest exposure increases occurred among:
- Working-age men: +24%
- School-age children: +18%
This occurred because more time was spent inside homes using biomass fuels, even while outdoor air improved.
Global Implications
The study conservatively estimates that 34.5% of the global population experienced increased PM₂.₅ exposure during lockdowns—primarily in low-income regions with high biomass fuel use.
Why This Matters
The findings challenge a common narrative that lockdowns universally improved air quality exposure.
Even during historically clean outdoor air conditions, household biomass burning drove higher exposures for millions.
The study reinforces:
- Clean cooking is central to air quality policy
- Household energy transitions are critical for environmental justice
- Exposure reduction must address indoor environments—not only ambient air
Read the full article: https://doi.org/10.1088/1748-9326/ac9703
High-Resolution Vehicular Exhaust and Non-Exhaust Emission Analysis in an Urban–Rural District of India
Science of the Total Environment (2022)
Authors: Gaurav Tomar, Ajay Singh Nagpure, Vivek Kumar, Yash Jain
Sector: Transport Emissions | Urban–Rural Air Pollution | Emission Inventory | PM₂.₅
Study Region
This study was conducted in Saharanpur district, a North Indian urban–rural landscape located in the Indo-Gangetic Plain (IGP).
- Area: 3,689 km²
- Population density: 940 persons/km²
- Economy: Agriculture and agro-based industries
- Air pollution status: Limited local emission data despite being in a highly polluted region
The study addresses a major gap: transport emissions in smaller cities and rural areas are rarely analyzed at high resolution, even though pollution levels can rival megacities.
What This Study Did
The research developed a high-resolution (ward and village level) emission inventory for both:
- Exhaust emissions
- Non-exhaust emissions (brake wear, tire wear, road wear, and dust resuspension)
A novel vehicle trip simulation methodology was introduced to allocate:
- Vehicle population
- Vehicle kilometers traveled (VKT)
- Emissions across urban and rural road networks
Dispersion modeling was then used to estimate PM₂.₅ concentrations across the district.
Key Findings
1. Non-Exhaust Emissions Dominate
- On rural roads, 89% of vehicular PM₂.₅ came from dust resuspension and non-exhaust sources
- On urban roads, 75% of PM₂.₅ came from resuspended dust
This challenges the common focus on tailpipe emissions alone.
2. Rural Emissions Are Significant
Annual PM₂.₅ emissions:
- Urban area: 97 tons/year (exhaust) + non-exhaust sources
- Rural area: 236 tons/year (exhaust + non-exhaust)
Rural roads contributed a substantial share due to:
- Poor road conditions
- High dust resuspension
- Agricultural vehicle activity
3. Vehicle Category Differences
- Two-wheelers (2W) contributed significantly in urban areas
- Light commercial vehicles (LCVs), especially tractors, dominated rural emissions
4. Emission Allocation Matters
Traditional emission inventories that distribute emissions using only population or vehicle ownership misestimate rural contributions.
Incorporating realistic vehicle movement patterns significantly improves spatial accuracy.
Why This Study Matters
Most Indian transport studies focus on megacities. This study shows:
- Smaller cities and rural districts experience comparable vehicular pollution burdens
- Non-exhaust emissions are the dominant source of PM₂.₅
- Rural transport emissions are underestimated in national assessments
For policy:
- Road dust management is critical
- Rural mobility planning must be integrated into air quality strategies
- Emission control cannot focus only on engines
Read the Full Article https://www.sciencedirect.com/science/article/abs/pii/S0048969721053328
Epidemiology, Environmental Quality, and Socio-Economic Perspectives of the COVID-19 Pandemic
Journal of Environmental Management (2021)
Authors: Surindra Suthar, Sukanya Das, Ajay Nagpure, Chaithanya Madhurantakam, Satya Brat Tiwari, Pallavi Gahlot, Vinay Kumar Tyagi
Sector: Public Health | Air Quality | Waste Management | Environmental Systems | Socio-Economic Impact
What This Review Covers
This interdisciplinary review examines COVID-19 through a systems lens — connecting epidemiology, environmental quality, waste systems, and socio-economic impacts.
Rather than treating the pandemic only as a medical crisis, the study evaluates how public health, air pollution, wastewater, and solid waste systems interact during global disruption.
Key Themes
1. Epidemiology and Pathogenesis
- Overview of SARS-CoV-2 structure and transmission pathways
- Molecular characteristics of the virus
- Global spread patterns and public health response
- Diagnostic developments and rapid testing technologies
The review explains how viral structure and transmission mechanisms shape containment strategies.
2. Air Pollution and COVID-19 Mortality
- Significant global reductions in NO₂ and PM₂.₅ during lockdowns
- Evidence suggesting that highly polluted regions experienced higher COVID-19 mortality rates
- Discussion of pre-existing respiratory vulnerability in polluted regions
The findings highlight how chronic air pollution may amplify health risks during respiratory pandemics.
3. Wastewater Surveillance
- SARS-CoV-2 detected in wastewater systems
- Wastewater monitoring proposed as an early warning system for community spread
- Importance of sanitation infrastructure in public health resilience
This section emphasizes environmental monitoring as a tool for disease tracking.
4. Solid and Hazardous Waste Management
- Increased medical waste (PPE, masks, gloves)
- Disruptions in municipal solid waste systems
- Pressure on hazardous waste treatment infrastructure
The pandemic exposed structural weaknesses in waste management systems globally.
5. Socio-Economic Impacts
- Job losses and economic slowdown
- Increased public health expenditure
- Disproportionate impact on vulnerable populations
- Compounded burden in regions already facing environmental stress
The review frames COVID-19 as both a health crisis and a socio-environmental systems shock.
Why This Study Matters
This work connects:
- Air pollution
- Public health vulnerability
- Waste systems
- Environmental monitoring
- Economic resilience
It demonstrates that pandemics must be addressed through integrated environmental and public health systems planning.
Access the Article https://www.sciencedirect.com/science/article/pii/S030147972031625X
Assessment of Illegal Dumped Municipal Solid Waste (MSW) in Delhi
Resources, Conservation & Recycling (2019)
Author: Ajay Singh Nagpure
Sector: Urban Waste Management | Environmental Inequality | Solid Waste Systems
Study Focus
This study develops the first field-based method to quantify illegally dumped municipal solid waste (MSW) at the neighborhood scale in an Indian city.
While cities report average waste collection efficiency, no method previously existed to measure how much waste is actually accumulating on streets and open areas — especially across neighborhoods with different socioeconomic status (SES).
Delhi is used as the case study.
Why This Matters
In many Indian cities:
- Only 50–90% of daily waste is officially collected
- The remaining 10–50% accumulates illegally
- No reliable system existed to measure the mass and composition of this uncollected waste
Illegal dumping is not just a sanitation issue — it reflects infrastructure gaps and environmental inequality.
Method Developed
The study introduces a neighborhood-level field approach combining:
- Urban transect sampling
- Manual weighing of waste piles
- 3D scanning for volume estimation
- Composition analysis of dumped waste
- SES-based neighborhood comparison
This method enables:
- Estimation of waste mass per km²
- Measurement of collection efficiency at micro-level
- Intra-city inequality assessment
- City-scale extrapolation
Key Findings
- 557,000 tons of MSW were illegally dumped across Delhi
- Low-SES neighborhoods showed the highest burden
- 61 kg per capita illegally dumped waste in low-SES areas
- 100× higher per km² dumping compared to high-SES areas
- Only 67% of generated waste in poor neighborhoods reached landfills
- Compared to 97–99% in wealthier areas
- Delhi would require two additional months to clear accumulated illegal waste
Environmental Inequality
Illegal dumping was strongly correlated with:
- Lower income neighborhoods
- Poorer waste collection infrastructure
- Reduced municipal service access
The study demonstrates that city-wide waste efficiency numbers mask severe intra-city disparities.
Policy Implications
The findings highlight the need for:
- Neighborhood-sensitive waste management planning
- Improved collection services in low-SES areas
- Transparent measurement of real collection efficiency
- Environmental justice–oriented infrastructure investment
This work provides a scalable framework for other developing cities facing similar waste management challenges.