Wildfires and heatwaves are threatening to undermine global efforts to improve air quality, protect human health and safeguard ecosystems by producing microscopic pollutants that can remain suspended in the air, the World Meteorological Organization said Monday.
The United Nations weather and climate agency highlighted the close links between air pollution and climate change, which scientists say is contributing to more frequent and intense heatwaves and wildfires.
“Extreme wildfires are increasing, leading to big health consequences because of the high toxicity of smoke,” the WMO said in a statement accompanying its latest annual Air Quality and Climate Bulletin.
The agency said regulations in Europe and North America have helped reduce industrial and transportation emissions of fine particulate matter, known as PM2.5. However, exposure to PM2.5 from wildfires has increased, offsetting some of those gains.
PM2.5 consists of microscopic particles and droplets measuring less than 2.5 micrometers in diameter. Because the particles are so small, they can penetrate deep into the lungs and enter the bloodstream, posing a serious risk to human health.
PM2.5 is emitted by fossil fuel-driven industrial activities, farming, domestic heating and transportation, as well as by wildfires and dust storms.
The report said the world needs to better monitor air pollutants such as aerosols, including black carbon and microplastics, fine particles and ground-level ozone.
These pollutants “are not sufficiently monitored even though they are widespread and are potentially harmful to ecosystems,” the WMO said.
“(We need) complementary and coordinated policies on air quality and climate because they cannot be dealt with in isolation.”
“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.
“In places where there are relatively powerful forest fires, we find a lot of fine particle pollution,” he said.
Microparticles generated by burning vegetation are “much more toxic” than those emitted by other sources, including car exhaust, he said.
They can harm the health of people and wildlife living far from the fire because they are carried by the wind, but their poisonous effects are not sufficiently taken into account in air quality assessments, Labrador said.
“Conventional risk models based on total PM2.5 concentrations may underestimate wildfire-attributable mortality by up to 93 percent,” the WMO said.
One study cited in the WMO bulletin said extreme fire-smoke events have tripled globally since the 1990s, contributing to nearly 100,000 additional deaths per year between 2010 and 2018, although that figure may be an underestimate.
Another source of air pollution that carries major health risks is ground-level ozone, which accumulates when temperatures rise, atmospheric conditions stagnate and solar radiation is intense, as seen during recent heatwaves in China, Europe and the southeastern United States.
“This increased exposure to ozone pollution has the potential to lead to tens of thousands of additional premature deaths,” particularly due to respiratory diseases, the WMO warned.
Another growing concern is aerosol particles, which can travel to oceans and continents far from their source.
They can alter the way the atmosphere reflects sunlight, change the chemical properties of land and water, and pollute otherwise clean environments.
“One example is the deposition of black carbon, or soot, on snow and ice, which reduces the amount of sunlight reflected by these surfaces and in turn can hasten the melting process,” the WMO explained.
Another example is microplastics, which form when plastics break down because of sunlight or other factors and are found virtually everywhere, including in the air, soil and oceans.
One simulation in the WMO bulletin estimates there are “51 million tonnes for land and 22 million tonnes for the ocean, which are in turn a source of microplastics for the atmosphere.”
“As plastic production and, critically, mismanaged plastic waste, continues to increase,” monitoring the airborne paths that carry microplastics from their source and deposit them in remote environments will be “crucial,” the report said.
