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 the last update of WHO recommendations, better monitoring and science have cleared up the global picture about the effects of six major air pollutants on human health. According to the agency, 90 per cent of the world's people already live in areas with at least one particularly harmful type of pollutant.

The revisions also highlight another — and often parallel — aspect to environmental concerns beyond widespread worries about global warming and the impact of burning fossil fuels.

Exposure to air pollution is estimated to cause seven million premature deaths and affect the health of millions more people each year, and air pollution "is now recognized as the single biggest environmental threat to human health," said Dr. Dorota Jarosinska, WHO Europe program manager for living and working environments.

Air pollution is now comparable to other global health risks like unhealthy diet and tobacco smoking, WHO said.

The guidelines, which are not legally binding and intended as a reference for policymakers, advocacy groups and academics, lower the advised concentrations of six pollutants known to have impacts on health: