In north India’s autumns, particularly around the week of Diwali, smoke from crop burning adds to the annual Diwali spike in the air quality index, or AQI. The geography of the Indo-Gangetic plains, changes in the pattern of prevailing winds and temperature inversions common at this time conspire to trap the dirty air in place. In that week, and through much of the later winter season, India’s air pollution problem springs sharply into focus.A recent study showed that 83 of the 100 most polluted cities in the world were in this country. This isn’t a problem only in parts of northern India — whether in the north, south, east or west, air pollution levels are stubbornly high. Progress in reducing them has stalled even as the health toll rises.AdvertisementData BlindspotsIn India, the AQI is calculated based on the amounts of eight pollutants in the air we breathe. Of them, PM2.5 and PM10 represent the concentration, by mass, of particles of size up to 2.5 microns and up to 10 microns. The other pollutants are nitrogen dioxide, sulphur dioxide, carbon monoxide, ozone, ammonia and lead. The first three are associated with the burning of diesel, coal and petrol, with biomass burning an additional major source of carbon monoxide and small particles in India.The official AQI, as the CPCB in India calculates it, is represented by the pollutant with the worst sub-index. This can understate the combined risk of several pollutants. Other carcinogenic chemicals such as benzene, arsenic and nickel are left out altogether. Further, values for the AQI are capped at 500, pulling the daily figure down during extreme episodes. Any hourly PM2.5 reading above 380 gives a sub-index of 500, so this Diwali’s peak of 3,744 at Mundka counted for no more than 380 would.The absence of data can mislead. For example, at 1 am on November 9, 36 of Delhi’s 59 stations had no PM2.5 reading in the CPCB’s records, while all 125 missing station-hours over the night exceeded a reading of 1,000 on DPCC’s site. A 24-hour average built from the remaining hours leaves out the worst ones; a station with fewer than 16 hours gets no sub-index at all. Averaging also dilutes the peaks.AdvertisementThe Mounting Health BurdenAn analysis of 2019 data attributed 1.67 million deaths to air pollution, about 18 per cent of all deaths in India. The State of Global Air 2025 report puts the figure at about 2 million in 2023, finding that about two-thirds of COPD deaths and 36 per cent of stroke deaths could be attributed to air pollution, as well as more than one in four heart disease deaths.Also Read | At COP31, look beyond the biggest emittersLower respiratory infections linked to air pollution caused four times the disease burden of those linked to tobacco in 2017, mostly affecting young children and older adults. An ICMR study of 33,213 patients in five cities linked higher-pollution days to more respiratory emergencies.In a Delhi cohort, higher PM2.5 exposure over one year was associated with a more than 50 per cent higher risk of hypertension. COPD in non-smokers shows a distinctive Indian pattern, with biomass smoke a major risk factor: Non-smokers with COPD were younger and equally male and female. The link between PM2.5 and diabetes is on a strong footing. A 2024 Lancet Commission named air pollution among 14 modifiable risk factors for dementia. Soot particles have been found in cord blood and in first- and second-trimester fetal liver, lung and brain tissue. Anaemia in young children rises with PM2.5, an unexpected link.Cosmetic Fixes vs Systemic OverhaulsAnother, more graphic way of understanding these impacts is to say that a resident of Delhi could gain roughly 8 to 10 years of life if the air met WHO guidelines.The government has stated that India lacks conclusive data linking deaths exclusively to air pollution. That is technically true, because these are attributable estimates rather than counts of individual cases. However, the Indian studies above consistently point the same way, and the main uncertainty is the size of the effect at India’s very high exposures rather than whether harm occurs.Imposing strict standards on automobile pollution and reducing the absolute numbers of vehicles on the ground are imperative; there has been progress on the first but little on the second. Measures that halt construction across Delhi in the affected months and that reduce the spike during Diwali are not long-term fixes. Cleaner fuel and vehicle standards have the strongest evidence, while evidence for the success of the odd-even rotation is weak. Sprinklers and smog towers have negligible impact and are simply cosmetic measures.Overcoming Political ApathyThe problem of vehicular pollution will not go away unless vehicle use and purchase are taxed at far higher rates, until parking costs are hiked to seriously discourage car use, and unless public transportation that is affordable and accessible becomes the default option. A switch away from biomass burning, as envisaged in the Pradhan Mantri Ujjwala Yojana, is one decisive policy step. Accelerating a shift to electric vehicles and ensuring better last-mile connectivity by better coupling the metro system to a bus network would be another. And, of course, more rigorous enforcement is needed, particularly of pollution caused by industrial units and waste-burning.you may likeAir pollution is a wicked problem. It calls for cooperation across states, indeed countries, since it affects an airshed common to Pakistan, Nepal, the Indo-Gangetic plain and Bangladesh. What’s surprising is the public apathy towards the air pollution question, an apathy similar to that seen towards issues of climate change. Both may have their roots in the same thinking: That individuals cannot move the scale on what is essentially a collective action problem and, more cynically, that the incentives behind our politics will only reward short-term thinking.To be cynical is a personal choice, but no longer a viable one at this point, since we all breathe the same air. The outlook for India is grim. The courts must act to hold the government to account.The writer is professor at Ashoka University. The views expressed here are his own and do not represent those of his institution