Ambient Air Pollution Levels Around the World?

Around the world, ambient levels of PM2.5 continue to exceed the Air Quality Guideline established by the World Health Organization (WHO). WHO set the Air Quality Guideline for annual average PM2.5 concentration at 10 μg/m3 based on evidence of health effects of long-term exposure to PM2.5 but acknowledged that it could not rule out health effects below that level. For regions of the world where air pollution is highest, WHO suggested three interim targets set at progressively lower concentrations: 35 μg/m3, 25 μg/m3, and 15 μg/m3. Figure 2 shows where these guidelines were still exceeded in 2016.