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Delhi’s toxic air has become a full-blown public health emergency, with local emissions and trapped winter pollutants driving the worst AQI levels in years
Image Source: Getty Images
The catastrophic air quality crisis in New Delhi has become a recurring feature of the national capital, posing serious concerns. With countless people in the National Capital Region (NCR) breathing harmful Particulate Matter ≤ 2.5 (µm) (PM2.5) pollutants daily, the impact of the skyrocketing Air Quality Index (AQI) levels amounts to a public health emergency. Invisible pollutants have resulted in hazardous air quality across the northern regions of the Indian subcontinent, with no catch-all solution. To confront Delhi’s air crisis effectively, policy intervention must be an urgent priority, grounded in the latest empirical data, and prioritise immediate actions against local pollution sources.
Delhi’s wintertime spikes in AQI levels are caused by a myriad of factors, worsened by unfavourable meteorological conditions that trap pollutants close to the surface. Vehicular emissions, waste incineration, displaced dust, stubble burning, firecrackers, and construction have been identified in a report as some of the contributing factors. For years, stubble burning has been singled out as the leading contributor, as pollutants travel across state borders during periods that correlate with increased PM 2.5 pollutants in Delhi. However, newly published data from the Central Pollution Control Board (CPCB) demonstrates that the proportional contribution of stubble burning to Delhi’s PM2.5 in 2025 is negligible.
Source: Central Pollution Control Board (CPCB)
Despite a 77.5 percent decrease in stubble burning since 2021, Delhi’s air quality reached its worst in half a decade this winter. As illustrated above, the contribution of stubble burning to PM2.5 levels has dropped to negligible proportions. The CPCB’s report has measured AQI only between 1 January and 7 November each year, discounting some of the most severely polluted days. Regardless, the proportional contribution of stubble burning has reduced substantially since 2021, even during the peak period of early November. This aligns with the most recent data from the Centre for Science and Environment (CSE), which highlighted that local emissions from vehicles and combustion sources are the most significant contributors.
The city's basin-like topography, combined with colder temperatures, creates temperature inversions where cold air is trapped beneath warm air, preventing pollutants from escaping.
The city's basin-like topography, combined with colder temperatures, creates temperature inversions where cold air is trapped beneath warm air, preventing pollutants from escaping. Pollutant mixing occurs much closer to the ground in the coldest months, exacerbated by lower moisture and calm winds during winter. Furthermore, recent changes, such as the Supreme Court permitting the use of green firecrackers in Delhi-NCR during Diwali, risk aggravating seasonal spikes in air pollution. These conditions are even more precariously placed following the Supreme Court’s recent acceptance of a uniform definition of the Aravalli Hills that removes protections for nearly 90 percent of the range from large-scale mining. This could worsen Delhi’s air, leading to the loss of vital green cover and natural barrier for desert dust and regional pollutants that the Aravallis provide.
As things stand, sustained local emissions and the meteorological factors that worsen the impact are causing an escalation of the effects of climate change as well as an immediate health crisis.
Air pollution is a significant threat to public health, particularly in North India, where almost the entire population lives in regions with PM2.5 levels exceeding the World Health Organisation (WHO) standards. PM2.5, the most harmful pollutant, which directly reaches deep into the lungs, is linked to increased incidence of respiratory and cardiovascular diseases, including chronic obstructive pulmonary disease (COPD) and non-smoker lung cancer. The WHO estimates that globally, approximately 4.2 million premature deaths associated with ambient air pollution occur annually.
An analysis of the Global Burden of Disease data found that in 2023, air pollution contributed to 15 percent of all deaths in Delhi, amounting to 17,188 deaths – an 8.9 percent increase since 2018 – making it the leading cause of mortality in the city and the biggest threat to residents. While research is still being conducted to better understand all the health risks of air pollution, besides lung and heart disease, air pollution is also associated with impaired cognitive function, increasing the risk of stroke and dementia, hormone disruption and weakening of immune defences, among others. For children with developing lungs, air pollutants are associated with stunted growth and increasing lifelong respiratory risks.
Between 2022 and 2024, 204,758 cases of ARI were reported to emergency department, of which, 30,424 required hospital admission, demonstrating the burden of air pollution on Delhi’s population.
Data collected by the National Centre for Disease Control (NCDC) under the Acute Respiratory Infection (ARI) digital surveillance, started in August 2023, from six central government hospitals in Delhi revealed that between 2022 and 2024, 204,758 cases of ARI were reported to emergency department, of which, 30,424 required hospital admission, demonstrating the burden of air pollution on Delhi’s population.
The National Clean Air Programme (NCAP) – India’s principal policy framework for improving air quality in 131 cities – set the target of a 40 percent reduction in PM10 concentrations compared to 2017–18, or compliance with the National Ambient Air Quality Standards (NAAQS, 60 μg/m³ for PM10, 40 μg/m³ for PM2.5) by 2026, and outlined rigorous measures to mitigate air pollution in major cities. While some progress has been made, Delhi, Gurgaon, and Noida ranked among the highest for both PM10 and PM2.5 concentrations.
Further, the National Ambient Air Quality Standards (NAAQS) target is far more lenient than the recommended limit by the WHO (20 μg/m³ for PM10, 10 μg/m³ for PM2.5), and air pollution at NAAQS levels can also adversely impact health.
Fund utilisation of the NCAP reveals a disproportionate focus on road dust management (67 percent of expenditure). On the other hand, only four percent of the funds are dedicated to capacity building and monitoring. While road dust management is important, allocating resources towards curbing vehicular emissions and open waste burning could do more to reduce local pollutants.
The National Ambient Air Quality Standards (NAAQS) target is far more lenient than the recommended limit by the WHO (20 μg/m³ for PM10, 10 μg/m³ for PM2.5), and air pollution at NAAQS levels can also adversely impact health.
An investigation revealed that nearly 22 air quality monitoring stations in Delhi violated CPCB guidelines, with several located near vegetation or obstructions that could affect their readings. Additionally, poor maintenance and violation of guidelines undermine the data’s reliability. Under the System of Air Quality and Weather Forecasting and Research, technology has also been developed to predict pollution levels in Delhi and ensure preventative actions to protect human health.
The National Programme on Climate Change and Human Health (NPCCHH) developed a comprehensive Health Adaptation Plan for Diseases due to Air Pollution (HAP) in 2021, which outlines response measures such as a graded health response to changes in AQI to manage the surge in respiratory and cardiopulmonary diseases due to air pollution. It encompasses health facility preparedness, stockpiling medications, and public advisories. However, monitoring and forecasting gaps based on air pollution data constrain policy response, leaving cities without critical early warning systems or advanced risk communication for their populations. This holds for the Graded Response Action Plan (GRAP) as well, which mandates phased restrictions on construction, traffic, and industrial activity as air quality worsens. However, its effectiveness depends on timely and credible data. Even in its most advanced stage (GRAP-IV), the restrictions provided some relief but failed to resolve the underlying issues before these were relaxed once again. Nonetheless, the importance of an emergency response mechanism that halts construction and reduces public exposure to the toxic air should not be underestimated.
Collectively, despite the existence of frameworks, policy responses have fallen short in implementation, and urgent measures must be taken to mitigate the root causes of Delhi’s air pollution and its impacts on public health.
An investigation revealed that nearly 22 air quality monitoring stations in Delhi violated CPCB guidelines, with several located near vegetation or obstructions that could affect their readings.
Amid growing recognition of the adverse impacts of air pollution, the Supreme Court described Delhi-NCR’s air quality as a ‘health emergency,’ while agreeing to hear a plea seeking urgent, time-bound action to curb rising pollution levels. In parallel, the return on investment (ROI) of controlling air pollution was estimated to be US$30 for every dollar spent in the United States (US), including the benefits of reduced healthcare costs, improved worker productivity, and extended life expectancy, reinforcing that clean air should be treated as a public-health and economic priority. Acknowledging the severity of the crisis, in the short run, efforts across the NCAP, the HAP, and the GRAP need to be aligned so that air quality data can trigger responses across both environmental and health sectors. This would require combined data dashboards and joint control rooms to take unified action.
Nevertheless, to truly combat air pollution and prevent a public health emergency, there must be a multifaceted effort. In addition to the restrictions placed by GRAP, which can mitigate the sources of pollution during spikes, long-term measures to reduce vehicular emissions include accelerating the transition to clean energy, improving public transport networks, and enhancing last-mile connectivity with zero-emission options and demand management tools such as congestion taxes. Proper segregation and collection of waste will reduce open burning, another major contributor to pollutants. Industrial sources in and around Delhi need tighter emissions standards, continuous monitoring and strict enforcement, especially for heavily polluting industries.
Nimisha Chadha is a Research Assistant with the Centre for New Economic Diplomacy at the Observer Research Foundation.
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Nimisha Chadha is a Research Assistant with ORF’s Centre for New Economic Diplomacy. She was previously an Associate at PATH (2023) and has a MSc ...
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