Wildfire smoke and extreme heat erode clean-air gains, WMO finds
The World Meteorological Organization’s Air Quality and Climate Bulletin No. 6 says wildfire smoke is eroding reductions in industrial and transport PM2.5 emissions in Europe and North America. Heatwaves are also increasing ground-level ozone. In 2025, fine-particle concentrations remained above the long-term average in northern Canada, parts of Russia, western-central Africa and north-western Spain because of fire activity.
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The bulletin tracks air quality and climate together
The World Meteorological Organization released Air Quality and Climate Bulletin No. 6 on September 7. It reports a decline in industrial and transport PM2.5 emissions in Europe and North America and an increase in exposure to fine particles in wildfire smoke. Ground-level ozone readings are also higher in periods of prolonged, intense heatwaves. The bulletin tracks fine particles and ozone as separate indicators within the same assessment of air quality.[1], [2]
The 2025 observations vary across regions
In WMO’s assessment for 2025, fine-particle concentrations remained above the long-term average in northern Canada, parts of the Russian Federation and western-central Africa; the bulletin also recorded fire activity in those regions. North-western Spain, which experienced exceptional late-summer fires, was in the same group. Burning in Amazonia was lower than in previous years. China remained below its long-term average, while India stayed above it.[1]
Four model sources pointed in broadly the same direction
For the first time, the bulletin brought together model results from four sources and reported that their results were broadly consistent. WMO also called for closer monitoring of black carbon and microplastics. The Guardian reports two separate trends in the bulletin: declining traffic and industrial pollution, and increasing exposure to wildfire smoke. It also reports higher ground-level ozone readings in prolonged periods of extreme heat.[1], [2]
