Wildfire smoke threatens air quality gains, WMO says

Wildfire smoke and heatwaves risk weakening global progress on cleaner air and public health, the World Meteorological Organization said in its latest annual Air Quality and Climate Bulletin.

The United Nations weather and climate agency said air pollution and climate change are closely linked, with scientists saying climate change is leading to more frequent and intense heatwaves and wildfires.

The WMO said rules in Europe and North America have reduced industrial and transport emissions of PM2.5, a fine particulate pollutant, but exposure to PM2.5 from fires has increased. PM2.5 particles are less than 2.5 micrometres wide and can enter the lungs and bloodstream.

Lorenzo Labrador, from the WMO's Global Atmosphere Watch network, told AFP that particles from burning vegetation are more toxic than particles from other sources, including car exhaust. He said wind can carry the particles far from fires, harming people and wildlife away from the flames.

The WMO said conventional risk models based on total PM2.5 concentrations may underestimate deaths attributable to wildfires by up to 93 percent. A study cited in the bulletin said extreme fire-smoke events have tripled globally since the 1990s and contributed to nearly 100,000 additional deaths a year between 2010 and 2018, though that figure may be an underestimate.

The agency also warned about ground-level ozone, which can build up when temperatures rise, air stagnates and sunlight is strong. It said increased ozone exposure during recent heatwaves in China, Europe and the southeastern United States could lead to tens of thousands of additional premature deaths, especially from respiratory diseases.

The bulletin called for better monitoring of aerosols, fine particles, ground-level ozone and airborne microplastics. The WMO said black carbon on snow and ice can reduce reflected sunlight and speed melting, while microplastics are now found in air, soil and oceans.