air quality

In Delhi, the air quality dips substantially during winter months due to stubble burning in neighbouring states© S. Priyadarshini

The life expectancy of Delhi residents may be reduced by as much as nine years if current air pollution levels persist, according to a new report by research group Energy Policy Institute at the University of Chicago (EPIC).

Nearly 40% of India’s population is exposed to levels of pollution not endured in any other country, the report says. The 510 million residents in north India’s Gangetic region could be losing 8.5 years of life on average. The region is India’s most populated, with the states of Uttar Pradesh, Bihar and Bengal, and the mega cities of Delhi and Kolkata.

Air pollution shortens average life expectancy in India by 5.9 years, as measured by the Air Quality Life Index (AQLI), designed by economist Michael Greenstone and his team at EPIC. The index combines research that quantifies the causal relationship between long-term human exposure to air pollution and life expectancy, with hyper-localized, global particulate metrics to measure the true cost of particulate pollution on communities. Some areas of India fare much worse than average, lives shortened by 9.7 years in Delhi and 9.5 years in Uttar Pradesh if air pollution levels of 2019 persist.

The number of regions with high levels of air pollution has increased over time. “Compared to a couple of decades ago, particulate pollution is no longer a feature of the Indo-Gangetic plains alone. Pollution has increased so much in the states of Maharashtra and Madhya Pradesh that the average person in those states is now losing an additional 2.5 to 2.9 years of life expectancy, relative to the early 2000s", the report says.

The AQLI illustrates that adhering to WHO guidelines on safe levels of exposure, national air quality standards and user-defined air quality levels can increase life expectancy.

Over the last 18 months, when pandemic lockdowns caused industrial activities to cease, and air and road traffic was reduced, some urban areas experienced cleaner air. “It became acutely apparent the important role policy has played and could play in reducing fossil fuels that contribute both to local air pollution and climate change,” Greenstone told Nature India.

The report says that in 2019, India’s average particulate matter concentration (PM) was 70.3 µg/m³ — the highest in the world and seven times the WHO’s guideline of 10 µg/m³.

“Since 1998, the average annual particulate pollution has increased 15%,” says the study that analysed air pollution data from 1998 till 2019. While Delhi is the worst state, Uttar Pradesh tops the list for largest number of polluted cities with PM 2.5 concentration in Allahabad and Lucknow. This is 12 times higher than the WHO guidelines recommend.

By 2024, India’s National Clean Air Programme aims to reduce particulate pollution by 20% to 30% percent from 2017 levels. If it does achieve and sustain this cut, it would lead to a nationwide reduction of 25% percent in PM levels. This in turn would increase India’s national life expectancy by 1.8 years, and by 3.5 years for residents of Delhi.