WMO says wildfire smoke and heat are undoing hard-won clean-air gains

The World Meteorological Organization warned on Monday that wildfire smoke and heatwaves are cancelling air-quality gains that cities won by cleaning tailpipes and smokestacks. In its annual report on air quality and climate, the Geneva agency said meeting World Health Organization guideline levels will get harder because extreme fires are becoming more common, and because heat speeds the chemistry that makes ground-level ozone.

Lorenzo Labrador, a WMO scientific officer, put the bind in one sequence. A city can cut traffic and factory emissions and still breathe dirty air if a fire hundreds of kilometres away sends a plume over it. "No matter how clean your city or your region is because of reduced emissions due to whatever measures you put in place, if you have a lot of pollution brought about by wildfires, that has the potential to negatively impact air quality in those regions," he said.

The report tracks fine particles, PM2.5, and ozone, both tied to heart and lung disease. It found that 2025 PM2.5 readings sat above long-term averages in northern Canada, parts of Russia and western-central Africa because of fire. Northwestern Spain became a hot spot after late-summer burns. A study cited in the text found that extreme fire-smoke events have tripled worldwide since the 1990s and may have added nearly 100,000 deaths a year between 2010 and 2018. Labrador said fire particles carry a mix of toxic chemicals and that breathing them sets off inflammation through the body, not only in the lungs.

The health list in the report is specific. Systematic reviews link wildfire smoke to more asthma attacks, more hospital admissions for chronic obstructive pulmonary disease, higher use of respiratory drugs, and effects on mental health and birth outcomes. Heat adds a second pollutant. Ground-level ozone forms faster on hot days. Europe's long summer this year, with fires in Spain, France, Greece and Sicily, was the live example the authors had in front of them.

WMO also asked for better tracking of black carbon and of airborne microplastics, two things it says are still poorly measured even though they are widespread. That request is a research budget item as much as a warning. Satellites see smoke. They do not yet give health departments a daily, local number for the chemical mix inside it.

The policy point is coordination. Air statutes and climate statutes still live in different ministries in most capitals. Fire weather is a climate product. The smoke is an air-quality product. Treating them as separate problems produces the result the report describes: diesel filters go on trucks while a forest burns and the city's monitors spike anyway. Canada, Russia, Spain and the Sahel belt are the 2025 case studies. They will not be the last.

For health ministries the usable takeaway is timing. Heatwave plans and fire alerts now have to include hospital surge rules for asthma and COPD, not only cooling centres and evacuation maps. For environment ministries the takeaway is that a clean-air target written in 2015 does not hold if the fire season of 2026 is the new baseline. The WMO cannot set those rules. It can only show that the old split between climate policy and smog policy no longer matches the air people are breathing.