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Intensifying wildfires and heatwaves are threatening global efforts to improve air quality and protect public health, the World Meteorological Organization (WMO) warned on Monday, highlighting the growing link between climate change and air pollution.
In its latest annual Air Quality and Climate Bulletin, the United Nations weather and climate agency said increasingly severe heatwaves and wildfires are generating dangerous levels of microscopic airborne pollutants, with consequences extending far beyond the areas directly affected by fires.
“Extreme wildfires are increasing, leading to big health consequences because of the high toxicity of smoke,” the WMO said.
The agency noted that while regulations in Europe and North America have helped reduce PM2.5 emissions from industry and transport, exposure to fire-related fine particle pollution has increased.
PM2.5 consists of microscopic particles and droplets measuring less than 2.5 micrometres in diameter. Because the particles can penetrate deep into the lungs and enter the bloodstream, prolonged exposure poses serious risks to human health.
The pollutants are produced by fossil fuel-based industrial activities, agriculture, domestic heating and transport, as well as wildfires and dust storms.
The WMO said air quality and climate change were closely interconnected and required coordinated policy responses.
“Air quality and climate change can’t be dealt with separately. If one worsens, the other does too,” Lorenzo Labrador of the WMO’s Global Atmosphere Watch network of scientists told AFP.
Wildfire smoke poses growing health risks
The WMO warned that wildfire smoke can be particularly dangerous because fine particles produced by burning vegetation can travel long distances and affect communities far from the source of a fire.
Labrador said microparticles generated by vegetation fires could be more toxic than particles produced by many other sources, including vehicle exhaust.
The agency warned that conventional health risk models based on overall PM2.5 concentrations may significantly underestimate deaths linked specifically to wildfire smoke.
According to the WMO, conventional risk models could underestimate wildfire-attributable mortality by as much as 93 per cent.
One study cited in the bulletin found that extreme fire-smoke events have tripled globally since the 1990s and may have contributed to nearly 100,000 additional deaths annually between 2010 and 2018, although the actual figure could be higher.
The growing frequency and intensity of wildfires are closely linked to a warming climate, which is increasing the occurrence of extreme heat and creating conditions more favourable for large-scale fires.
Heatwaves worsen ozone pollution
The WMO also warned of the growing threat posed by ground-level ozone, another major air pollutant.
Ozone pollution can increase when temperatures rise, atmospheric conditions remain stagnant and solar radiation is intense. Such conditions have been observed during recent heatwaves in China, Europe and the southeastern United States.
The WMO said increased exposure to ozone pollution could lead to tens of thousands of additional premature deaths, particularly from respiratory diseases.
The report called for improved monitoring of a range of airborne pollutants, including aerosols, black carbon, microplastics, fine particles and ground-level ozone.
Many of these pollutants, the WMO said, are widespread and potentially harmful to ecosystems but remain inadequately monitored.
Black carbon and microplastics raise wider concerns
The bulletin also highlighted the environmental consequences of airborne particles that can travel thousands of kilometres from their original source.
Black carbon, commonly known as soot, can settle on snow and ice, reducing the amount of sunlight reflected by these surfaces and accelerating melting.
Microplastics are another growing concern. Formed as plastics break down through sunlight and other environmental processes, they have now been detected in the air, soil and oceans.
A simulation cited in the WMO bulletin estimated that around 51 million tonnes of microplastics were present on land and 22 million tonnes in the ocean, with both environments serving as potential sources of airborne microplastics.
As global plastic production and mismanaged plastic waste continue to rise, the WMO said monitoring how microplastics travel through the atmosphere and reach remote environments will become increasingly important.
The agency stressed that efforts to address air pollution and climate change must be pursued together rather than through separate policies.
With climate change contributing to more frequent and intense heatwaves and wildfires, the WMO warned that improving air quality and protecting public health will become increasingly difficult unless governments adopt coordinated action on both challenges.
