Indians could live four years longer on average, if India is able to reduce air pollution to comply with the World Health Organisation’s standards, according to the Air Quality-Life Index (AQLI) tool developed by the Energy Policy Institute at The University of Chicago (EPIC).

In Delhi, which was for two consecutive years in 2014 and 2015 ranked as the most polluted city in the world, people could live nine years longer if it met WHO standards. And, six years longer if it met the country’s own national standards.

Residents of Kolkata and Mumbai could live roughly 3.5 years longer if the accepted particulate matter levels conformed to WHO standards, the tool show.

According to WHO, reducing annual average particulate matter (PM10) levels from 70 to 20 micrograms per cubic metre (µg/m3) can cut air pollution-related deaths by around 15 per cent.

A WHO factsheet of September 2016 states that the annual acceptable mean for PM2.5 has been set at 10 µg/m3 and for PM10 at 20 µg/m3. The national guidelines in India have set the annual acceptable mean for PM2.5 at 40 µg/m3 and PM10 at 60 µg/m3.

Indians could live more than a year longer on average, or a combined more than 1.6 billion life years, if the country reduces pollution to comply with its national standards, the AQLI reveals. According to official figures, the average life expectancy in India is 67.3 for males and 69.6 for females.

The AQLI “translates particulate….