80% of the World's Population Lives With Unsafe Air Pollution

More than 80% of the world's urban population lives in areas where air quality does not meet standards set by the World Health Organization (WHO), according to a new report.

The report, which looked at levels of small but damaging pollutants known as particulate matter, suggests that global urban pollution levels increased by 8% in the five years preceding 2013. That increase in pollution levels hit poor countries particularly hard, according to the report.