The AQLI said that Delhi is the most polluted city in the world.
Delhi has emerged as the world's most polluted city in a new study, which also found that its residents are on track to lose 11.9 years of life if the current levels of pollution persist.
The Air Quality Life Index (AQLI) released by the Energy Policy Institute at the University of Chicago also showed that all of India's 1.3 billion people live in areas where the annual average particulate pollution level exceeds the 5 μg/m3 limit set by the World Health Organisation (WHO).
It also found that 67.4 percent of the country's population lives in areas that exceed the country's own national air quality standard of 40 μg/m3.
The study said fine particulate air pollution (PM2.5) shortens an average Indian's life expectancy by 5.3 years, relative to what it would be if the 5 μg/m3 pollution limit of by (WHO) was met.
The AQLI said that Delhi is the most polluted city in the world, with its 18 million residents on track to lose 11.9 years of life expectancy on average relative to the WHO limit and 8.5 years relative to the national guideline if the current pollution levels persist.
"Even in the least polluted district in the region—Pathankot in Punjab—particulate pollution is more than seven times the WHO limit, taking 3.1 years off life expectancy if current levels persist," it said.
Though particulate pollution in the northern plains is exacerbated by geologic and meteorological factors, the AQLI's dust and sea salt-removed PM 2.5 data imply that human activity plays a key role in generating severe particulate pollution.
That is likely because the region's population density is nearly three times that of the rest of the country, meaning more pollution from vehicular, residential, and agricultural sources, the study said.
"Three-quarters of air pollution's impact on global life expectancy occurs in just six countries—Bangladesh, India, Pakistan, China, Nigeria, and Indonesia—where people lose one to more than six years of their lives because of the air they breathe," said Michael Greenstone, the Milton Friedman Distinguished Service Professor in Economics and creator of AQLI.