UNEP: Air pollution from wildfires expected to surge as world warms

When wildfires swept across western North America in the summer of 2021, they left a path of destruction in their wake, razing forests, farmland and even entire towns.

But new science suggests the fallout from the blazes extended far beyond those charred landscapes.

The wildfires released harmful fine particulates known as PM2.5 that spread over hundreds of kilometres of the western United States and Canada, according to a recent report from the United Nations World Meteorological Organization (WMO).

With the climate crisis expected to spark a surge in wildfires — their numbers could grow by 50 per cent by 2100 — experts are worried about the toll future blazes could take on human health.

“The fallout from wildfires is widespread and if, as the models suggest they become more common, they could potentially affect both people an animals across a wide swath of the planet,” says Jacqueline Alvarez, Chief of the United Nations Environment Programme’s (UNEP’s) Chemicals and Health Branch.

Air pollution is responsible for about 7 million premature deaths annually, or about 10 per cent of all fatalities.

In the recent WMO report, researchers said they used satellite data and ground-based monitoring to track the spread of air pollution during the 2021 summer fire season in North America and Russia. They focused on PM2.5. While more than 40 times smaller than a grain of sand, in high enough doses it can aggravate asthma, trigger lung disease, cause heart attacks and lead to premature death.

The study found that PM2.5 levels spiked over western North America, peaking at several times the level recommended by the World Health Organization. In Siberia, the concentration of PM2.5 hit a record high. In several North American cases, the particles reached excessive levels hundreds of kilometres from the source of the fires. Researchers called the potential health implications of that pollution a “great concern.”

Along with being sparked by humans, research shows that wildfires can be the result of a natural process. In some places climate change — and the hotter, dryer weather it is bringing — is making the blazes more intense and more common.


The number of wildfires is expected to increase by almost 15 per cent by 2030 and 30 per cent by 2050, found a UNEP-backed report released earlier this year. Even areas not normally thought of as fire-prone, such as wetlands and the Arctic, are at risk of going up in flames.

The report shows that wildfires and climate change are mutually exacerbating – a topic on the agenda this week at the UN Climate Conference in Egypt (COP27).

Wildfires are made worse by climate change through increased drought and strong winds resulting in hotter and longer fire seasons. At the same time, climate change is made worse by wildfires, ravaging sensitive and carbon-rich ecosystems.

Wildfires in peatlands can be especially problematic. Most of these are started by draining and burning peatlands for commercial agriculture and livestock use.

While peatlands cover less than 3 per cent of the Earth’s surface, they are the largest terrestrial warehouse of organic carbon and their burning releases the very greenhouse gases that are driving the climate crisis.

“The only permanent and sustainable way of preventing peat fires is to raise water levels and find ways to use the land while it remains wet,” said Johan Kieft, a UNEP peatland expert.

There are several recent examples of countries that have made progress in combating wildfires.

In Indonesia, where a series of wildfires impacted the health of thousands of people and caused $16 billion in losses in 2015, the government is working with 150 communities to train local communities in how to clear land without resorting to fires. The work, which includes restoring degraded landscapes, has been supported by the UN Collaborative Programme on Reducing Emissions from Deforestation and Forest Degradation in Developing Countries(UN-REDD).

Peatland monitoring processes were also used to prevent fires from happening again.

As the climate changes, countries will need to divert more money towards planning for and preventing wildfires, found the UNEP report, Spreading Like Wildfire. Right now, half of wildfire spending goes to responding to blazes; just 1 per cent is used for planning.

“We need to devote more resources to stopping fires before they happen,” said Alvarez. “If we don’t, the emerging science suggests it’s going to be bad for the health of people around the world.”