Wildfires and heatwaves emerge as growing threats to air quality

Wildfires and heatwaves are becoming a larger threat to air quality, potentially undoing efforts to reduce pollution from cars, industry and heating systems, the World Meteorological Organization said in a new report.

The organization warned that pollution from wildfires and heatwaves could weaken international efforts to improve air quality and protect human health and ecosystems. Fires and sandstorms rank among the significant emission sources, alongside industrial activity and agriculture.

PM2.5 concentrations exceeded their long-term average in 2025 in northern Canada, parts of Russia and central-western Africa, which the report linked to increased fire activity. Northwestern Spain also recorded elevated levels after exceptional summer wildfires. Exposure to fire-related particles rose in Europe and North America even as industrial and transport emissions declined.

The World Health Organization estimates that major fires, which have tripled since the 1990s, may have caused about 100,000 additional deaths annually between 2010 and 2018. It said the figure could be an underestimate.

The meteorological organization said climate change may worsen the problem by promoting heatwaves and large fires. It urged countries to coordinate policies, improve monitoring and track pollutants that receive less attention. Heat can increase ground-level ozone, while stagnant air and strong sunlight can raise concentrations during heatwaves. Black carbon and soot from fires can travel long distances and darken snow and ice, reducing their ability to reflect radiation and accelerating melting.

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Increased pollution from wildfires and heatwaves can weaken international efforts to improve air quality and protect human health and ecosystems