GENEVA: Wildfires are releasing a “witches’ brew” of pollutants that can end up wrecking air quality a continent away from the blaze, the UN’s weather and climate agency said on Friday.
The World Meteorological Organisation said the quality of the air people breathe was interlinked with climate change, and the two issues needed to be tackled together.
Wildfires in the Amazon, Canada and Siberia have brought home how air quality can be impacted on a vast scale, the WMO said in its fifth annual Air Quality and Climate Bulletin.
“Climate impacts and air pollution respect no national borders, as exemplified by intense heat and drought which fuels wildfires, worsening air quality for millions of people,” said WMO deputy secretary-general Ko Barrett.
The bulletin looked at the interplay between air quality and the climate, highlighting the role of tiny particles called aerosols in wildfires, winter fog, shipping emissions and urban pollution.
Particles with a diameter of less than 2.5 micrometres (PM 2.5) are considered particularly harmful since they can penetrate deep into the lungs or cardiovascular system.
Wildfires led to above-average PM 2.5 levels in Canada, Siberia and central Africa last year, the WMO said. The biggest PM 2.5 surge, however, was in the Amazon basin.
Stronger, longer season
“The wildfire season has the tendency to be stronger and longer every year as a result of climate change,” said WMO scientific officer Lorenzo Labrador, who coordinated the bulletin.
Wildfires in Canada have ended up causing air pollution in Europe.
“We had that last year and this year as well. So you have a degradation in air quality across continents when the meteorological conditions are right,” Labrador told a press conference.
“What we have from these fires is essentially a witches’ brew of components that pollute the air.”
The World Health Organisation estimates that air pollution causes more than 4.5 million premature deaths every year.
The WMO called for improved monitoring and better policies to safeguard human and environmental health—and reduce agricultural and economic losses.
The bulletin highlighted pollution hotspots in northern India. It said the Indo-Gangetic Plain had seen a marked rise in air pollution and winter fog episodes, which are growing in frequency and duration due to pollution.
Improvement in China
PM 2.5 levels continued to decline in eastern China last year, which the WMO put down to mitigation measures.
When countries take measures to combat poor air quality, the improvement can be clearly seen in meteorological data, said Paolo Laj, the WMO’s global atmosphere chief.
“Look at Europe, Shanghai, Beijing, cities in the United States: many cities have taken measures and you see in the long term, a strong decrease” in recorded air pollution, he said.
Published in Dawn, September 6th, 2025
