India has the worst air quality in the world, poorer even than its neighbour China, according to an annual survey based at Yale and Columbia universities in the United States.
Of all the countries surveyed in the Environmental Performance Index (EPI), which measures the effects of polluted air on human health, India ranked the lowest at 132.
The study used satellite data to measure air pollution concentrations.
The level of fine particulate matter in India is nearly five times the limit where it becomes unsafe for humans, said the study released at the recent World Economic Forum in Davos, Switzerland.
Health experts say particulate matter is one of the main causes of acute lower respiratory infections and even cancer.
India scored a meagre 3.73 out of a possible 100 points in the air analysis, lagging way behind Bangladesh, the next-worst performer, which scored 13.66.
The region fared poorly with Nepal, Pakistan and China taking up the remaining spots in the bottom five of the rankings.
Explore further: Extreme weather in the Arctic problematic for people, wildlife