Delhi is now no longer the most polluted city in the world, stated the World Health Organisation on 12 May.
But India has four of the five cities with the worst air pollution in the world, added the organisation.
The country now ranks on the 11 place among 3,000 cities in 103 countries in terms of PM 2.5 (fine, particulate pollution) and 25th in terms of PM 10 (coarse pollution particles) levels. There has been an marked improvement since 2014 when Delhi was the worst city in the world in terms of pollution.
Presently, Zabol in Iran has been registered as the worst polluted city in the world. The city suffers from dust storms throughout the summer, and it clocked a so-called PM2.5 measure of 217. The next four were all Indian: Gwalior, Allahabad, Patna and Raipur.
Use of diesel-fuelled vehicles, waste management, heating and cooling of big buildings, agriculture and use of coal or diesel generators are the most common causes of air pollution.
On an average, the WHO said, pollution levels have worsened by as much as 8 percent between 2008 and 2013.