WHO: India tops in air pollution ratings

India is home to four of the five cities in the world with the worst air pollution, the World Health Organisation said.

But while WHO experts acknowledge India faces a “huge challenge”, many countries are so bad that they have no monitoring system and cannot be included in its ranking.

The dirtiest air was recorded at Zabol in Iran, which suffers from months of dust storms in the summer, and which clocked a so-called PM2.5 measure of 217.