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Why is India’s air so toxic?
Diwali is traditionally the worst time of year for air pollution—not just because of the fire crackers
NEARLY 1.7m people in India died in 2019 because of air pollution. In 2020 the covid-19 pandemic took around 1.1m lives, but covid-free Indians were at least blessed with cleaner air as factories closed and roads emptied. As the country returns to normal, the country’s air is re-toxifying. Millions of Indians celebrated Diwali on November 4th by lighting a barrage of smog-producing firecrackers, for example. The next day PM2.5 levels, a measure of the prevalence of microscopic particles that cause respiratory damage, touched 1,000 in parts of Delhi, the capital, 200 times higher than the healthy limit advised by the World Health Organisation.
Why is India’s air so polluted? Diwali celebrations may cause pollution to spike but there are bigger culprits that contaminate the air, especially during winter. One common way to quantify the mix of pollutants, from car fumes to factory emissions, is through inventories. These databases measure the source of air pollutants by sector over time. A recent report by the Council on Energy, Environment and Water (CEEW), a Delhi-based think-tank, examines five inventories compiled by global and Indian institutes.
The biggest source of PM2.5 is households. By burning solid fuels such as wood and dung to cook food and heat dwellings, they account for between 27% and 50% of the country’s emissions. But certain toxins, such as sulphur dioxide, are mostly produced by India’s coal-guzzling power sector. Somewhere between 44% and 66% of the sulphur dioxide emitted in India comes from power plants (see chart).
There are also regional variations. Poorer states such as Uttar Pradesh tend to account for disproportionately large shares of household emissions; farmers in agricultural states such as Punjab pollute the atmosphere by burning crop waste to optimise their harvests. This is particularly stark during early November, when the stubble from rice crops are incinerated to make room for wheat.
The varied sources of pollution make tackling the problem difficult. So does a lack of comprehensive data. Most government-commissioned studies focus on emissions at the city level, and ignore the vast swathes of rural India, which is often at least as polluted as the urban centres. The government wants to reduce the concentration of PM2.5 in cities by 20-30% by 2024. That would be more achievable if sector-specific emissions targets were set. But even CEEW’s sectoral emission estimates are from 2015 and 2016. Without updated and representative data, India’s environmental policies risk being as hazy as the country’s air. ■