Indonesia's Capital Jakarta Named World's Most Polluted City

Air pollution is estimated to contribute to seven million premature deaths every year and is considered by the United Nations to be the single biggest environmental health risk.

The capital and its surroundings form a megalopolis of about 30 million people that has outpaced other heavily polluted cities including Riyadh, Doha and Lahore all week for its concentration of tiny particles known as PM2.5.

It has topped Swiss company IQAir's ranking of pollution data -- which only tracks major cities -- every day since Monday, according to an AFP tally.