How much air pollution is too much? Global limits lowered for 6 pollutants

The World Health Organization (WHO) said Wednesday that the harmful health effects of air pollution kick in at lower levels than it previously thought and it is setting a higher bar for policymakers and the public in its first update to its air quality guidelines in 15 years.

The UN health agency released its revised air quality guidelines as climate change is a leading topic at the United Nations General Assembly in New York. Chinese President Xi Jinping announced Tuesday that China will no longer fund power plants fired by coal, which generates several of the pollutants covered by the guidelines.

Since