Air Pollution in India: The Silent Pandemic

During a recent event at the World Economic Forum in Geneva, economist and Harvard University Professor Geetha Gopinath stated that air pollution, not tariffs, is the greatest threat to the Indian economy at present. In an interview, the Editor-in-Chief of The Lancet, Dr. Richard Horton, minced no words, arguing that public apathy and a lack of political accountability are responsible for the growing problems of air pollution in India and its impact on public health. 1, 2 These voices reflect the pervasive challenge posed by ambient air pollution in India, which has evolved from a seasonal nuisance into a chronic public health emergency of unprecedented scale. As India, the world’s most populous nation, undergoes rapid urbanization, the atmospheric burden of pollutants such as particulate matter <2. 5 µm (PM2. 5), nitrogen dioxide (NO2), and ozone (O3) has reached concentrations that may alter population health. For the medical community, air pollution is no longer merely an environmental variable but a potent, modifiable risk factor for noncommunicable diseases. To provide general guidance on reducing global air pollution and associated mortality, the World Health Organization (WHO) has issued global air quality guidelines. The most recent guideline, in 2021, recommends a stricter annual PM2. 5 limit of 5 µg/m3, yet almost the entire 1. 4 billion population of India lives in regions that exceed this limit. 3 The Indian National Ambient Air Quality Standards set a less stringent annual PM2. 5 limit of 40 µg/m3; nevertheless, most Indian cities still have air pollution exceeding this limit. The health effects of this exposure to air pollution are enormous. In 2019, an estimated 1. 7 million deaths in India were attributable to air pollution, with nearly two-thirds attributable to particulate matter exposure and one-third to household air pollution. The economic losses from premature mortality and morbidity attributable to air pollution are estimated at approximately 36. 8 billion in 2019, accounting for 1. 36% of India’s gross domestic product. 4 A NATIONWIDE CRISIS WITH METRO HOTSPOTS Air pollution in India is not confined to a single city or season but constitutes a pan-India crisis with distinct regional characteristics. The pollution landscape is heterogeneous, influenced by local meteorology, geography, and source contributions. An “airshed” is a region that shares a common flow of air, which may become uniformly polluted and stagnant. An airshed can extend over a few hundred kilometers. The Indo-Gangetic Plain, encompassing Punjab, Haryana, Delhi, Uttar Pradesh, and Bihar, is one of the most polluted airsheds, particularly during the winter months (October–January). Stubble burning, coupled with a thermal inversion in which low winter temperatures trap pollutants near the surface, exacerbates the elevated, persistent baseline air pollution from vehicular emissions and construction dust. Delhi has become a symbol of India’s air quality challenges. In 2024, the daily average PM2. 5 concentration was 105 µg/m3, declining to 97 µg/m3 in 2025. 5 Even nonmetro cities in the Indo-Gangetic Plain, such as Patna, Lucknow, and Chandigarh, have pollution levels comparable to, or sometimes higher than, Delhi’s, due to eastward transport of pollutants and biomass burning, challenging the narrative that pollution is a megacity problem. While the coastal cities of Mumbai, Chennai, and Kolkata benefited from the sea breeze effect, which facilitated pollutant dispersion, recent analyses indicate a changing pattern largely driven by local emissions. South Indian cities such as Bangalore and Chennai still have lower annual pollution levels than northern Indian cities, but they are experiencing rapid localized deterioration driven by high vehicular density. In 2024, Gangtok, Sikkim, had the cleanest air, while Byrnihat, Meghalaya, had the most polluted air in India. 6 HEALTH IMPACTS: BEYOND “COUGH AND WHEEZE” Air pollution affects nearly every organ system. The effects on the respiratory system are well known and readily recognized. Increased upper airway irritation, cough and wheeze, exacerbations of asthma and chronic obstructive pulmonary disease (COPD), increased respiratory infections, and greater requirements for bronchodilators and nebulizers are common problems associated with air pollution. 7 Chronic exposure to pollutants may result in reduced lung function, COPD, and increased incidences of lung cancer. 7 AIR POLLUTION AND CARDIOVASCULAR DISEASES Air pollution is now recognized as a significant cardiovascular risk factor. The biological mechanisms by which inhaled particulate matter causes cardiovascular events are complex. Inhaled PM2. 5 leads to the production of pro-oxidative and pro-inflammatory mediators, including interleukin-6, tumor necrosis factor, and acute-phase reactants. These mediators also promote thrombosis, inflammation, endothelial dysfunction, increased blood pressure, and atherosclerosis, leading to adverse cardiac events. Alterations in cardiac function, cardiac rhythm abnormalities, and increased myocardial ischemic events are also attributed to increased air pollution. 8, 9 Short-term elevations in PM2. 5 increase the relative risk of CV events by 1%–3% within a few days. 10 Long-term cardiovascular complications, such as myocardial infarction, venous thromboembolism, cerebrovascular accidents, and cardiac arrhythmias, including atrial fibrillation, have also been noted to increase with increasing exposure to PM2. 5, resulting in shortened life expectancy by a few years. 7, 8 METABOLIC EFFECTS Air pollution also intersects with India’s cardiometabolic epidemic. The association between air pollution and insulin resistance and beta-cell dysfunction has been recognized and could add to the existing high burden of diabetes and cardiometabolic risk prevalent in India. 11 A study from two large cities, Chennai and Delhi, showed that a 10 µg/m3 increase in annual average ambient PM2. 5 concentrations was associated with a 22% increased risk of incident diabetes. 12 IMPACTS ON NEUROLOGICAL AND COGNITIVE HEALTH Growing evidence links air pollution to increasing incidences of stroke. A retrospective analysis using the burden-of-disease study found that between the period 1990 and 2021, the total recorded deaths attributable to air pollution-induced strokes in India, amounted to 8, 533, 316, with an average of 7, 983 deaths per year. The total Disability-Adjusted Life Years (DALYs) accrued due to strokes were over 204 million, averaging around 205, 890 DALYs annually. Additionally, the total Years of Life Lost (YLLs) totalled about 14, 836, 982, with a mean annual YLL of 192, 675. 13 Cognitive decline, risk of dementia, and worsened mental health symptoms in vulnerable individuals have also been attributed to air pollution. In a country with an increasingly aging population, these developments can have significant consequences for social and healthcare burdens. INCREASED MORTALITY AND IMPACT ON QUALITY OF LIFE A recent study demonstrated an association between ambient air pollution exposure and daily mortality in 10 Indian cities. More concerning is that some cities, despite PM2. 5 levels below national standards, experienced increased mortality, suggesting a nonlinear relationship and a need for more stringent ambient PM2. 5 cutoffs. 14 Such growing evidence makes it difficult to dismiss air pollution as merely “an irritant. ” It is a measurable driver of death, especially in vulnerable populations. Air pollution considerably impacts the quality of life by limiting mobility and exercise, causing sleep disturbances, chronic cough, fatigue, missed work, and reduced productivity. ADDRESSING THE PROBLEM India is taking numerous steps to address the problem. The Government of India has strengthened standards for vehicular and industrial emissions and is promoting renewable energy and electric vehicles. Millions of families are supplied with LPG cylinders to reduce the burning of wood for cooking. The National Clean Air Programme has set a time-bound goal to improve air quality, focusing on 132 “nonattainment” cities. Cities with populations exceeding 1 million will also receive performance-based funding to combat air pollution over the next 5 years. The World Bank has also been aiding India in air quality management through a strategic partnership. 15 Reducing emissions at source, expanding and modernizing public transport, shifting to electrification, enforcing vehicle emission standards, implementing effective traffic management, ensuring continuous emission monitoring in industries, adopting dust suppression practices at construction sites, enforcing strict accountability for construction compliance, maintaining zero tolerance for open waste burning, ensuring proper waste management and segregation, and processing are essential on the Government’s part to promote air quality. Medical professionals should identify high-risk patients, including older adults, and counsel them to reduce exposure. Advice on inhaler use and medication adherence, along with a healthcare system prepared for seasonal surges in respiratory or cardiac admissions, is essential. The most exposed people are the least able to protect themselves: traffic workers, street vendors, construction workers, and low-income households near roads and industrial zones are the most vulnerable to air pollution hazards and should be prioritized. It is estimated that air pollution reduces the average Indian’s life expectancy by 3. 5 years. Reducing PM2. 5 concentrations to meet the national standard of 40 g/m3 could add 1. 5 years to the life expectancy of the population living in areas exceeding the national standard. In the Indo-Gangetic plains, nearly 544 million residents could gain an average of 5 years of life expectancy if current pollution levels are reduced to the WHO guideline levels. If all of India were to meet the WHO particulate pollution standards, Delhi residents would be expected to gain 8. 2 years of life expectancy. 16 In terms of economic gains, a research report projected that targeted approaches to reduce PM2. 5 levels by 20% could generate over 200 billion in economic opportunity and support nearly 100 million job transitions or new jobs. 17 In conclusion, ambient air pollution in India is a systemic problem that pervades every aspect of health, from fetal and maternal health to older adults. Air pollution is a year-round, pan-India problem and requires scientific, well-coordinated, multi-stakeholder efforts to mitigate the associated risks. As medical professionals, we have a dual responsibility: managing the acute and chronic effects of this crisis in our clinics and advocating for the structural changes needed to achieve clean air. The potential to reclaim billions in economic value and millions of years of healthy life depends on the action taken in the next few years. Author contributions SNH is the sole author of this editorial and is involved with the literature review, manuscript writing and revisions. Data availability statement No new data was generated or analysed for this editorial and the data supporting the content are from the published literature cited in the references list.