When asked about the most polluted cities worldwide, most people usually name larger Chinese cities as being the worst air quality culprits.
However, according to research published by the World Economic Forum, Delhi is actually twice as polluted as Beijing. The level of PM 2.5 (micrograms per cubic meter) in Delhi is six times above the recommended World Health Organisation maximum.
In fact, out of the world's 15 worst cities, ten are in India while a further three are in Pakistan. Despite the fact that air pollution has become a massive social and environmental issue in China, no Chinese cities are present in the World Economic Forum's list of the top-15 worst offenders.
This chart shows PM 2.5 (micrograms per cubic meter) in the most polluted cities worldwide in 2014.
You will find more statistics at Statista