The study has also found that due to the poor quality of air, residents of Bihar might be losing 6.9 years on an average.

Even as Delhi battles air pollution, the condition of air quality in other states, such as Bihar, remains a cause for concern.

According to a study carried out by the Energy Policy Institute at the University of Chicago's Air Quality Life, residents of Bihar capital Patna could be losing 7.7 years of their life due to the bad quality of air.

The research team had conducted air quality analysis of various cities in the state from 1996 to 2016, and the findings of the study were then combined with the localised and global particulate measurements.The study has also found that due to the poor quality of air, residents of Bihar might be losing 6.9 years on an average. In 1998, according to the newspaper, the loss of life expectancy for residents of Patna was four years.

"The Air Quality Life Index (AQLI) tool suggests that if particulate pollution levels in Bihar were permanently reduced to the WHO standard, the average person would live nearly seven years longer, on average."

The World Health Organisation's guideline is 10 micrograms per cubic meter (µg/m3) and the national standards for India is 40 micrograms per cubic meter. The IE report states that potential gains in life expectancy are measured by lowering the PM2.5 concentrations to meet either the WHO guideline or nationally administered air quality standards.

AQLI shows that Siwan is the most polluted town in Bihar, and people in the town could live 9.01 years longer if the WHO guidelines on air quality are met. Nine district headquarters, including Sheohar, Bhojpur, Buxar, Gopalganj, Siwan, Muzaffarpur and Vaishali have air quality worse than Patna.

The study attains importance, since according to another study carried out by the Indian Institute of Technology (IIT) Delhi and Patna-based Centre for Environment and Energy Development, over 4,000 deaths occurred in Patna alone due to air pollution between the years 2000 and 2017.