Wildfires exacerbated by climate change played a major role in degrading global air quality last year, according to a new analysis.

The annual World Air Report published by the Swiss company IQAir claims wildfire smoke from Europe and Canada contributed to approximately 1,380 megatons of carbon being released across the world in 2025.

According to the study, Canada had its second-worst wildfire season on record last year, which affected air quality across Canada, the U.S and parts of Europe.

The report is based on data from monitoring stations across 9,446 cities in 143 countries, regions and territories.

The world’s 25 most polluted cities were all located in India, Pakistan and China, with India home to three of the four most polluted.

Regional Trends: North America, Europe And Asia

The most polluted major U.S. city was found to be El Paso, Texas, while South-East Los Angeles, California was the most polluted region.

The report says Europe saw mixed air pollution trends in 2025, with 23 countries recording higher PM2.5 concentrations and 18 seeing declines.

Winter wood burning, smoke from Canadian wildfires and Saharan dust were all said to worsen seasonal air pollution in Europe.

But the report also notes how air quality trends were largely positive in Latin America and the Caribbean.

The global chief executive of IQAir, Frank Hammes, said the Canadian and North American wildfires added between one or two micrograms of PM2.5 pollution in many European cities, in an interview.

“With climate change and other things affecting the intensity of certain weather events, we can expect a lot more these trans-boundary issues,” he told me.

Ccontrary to popular belief, dust is not harmless and can act as “little knives in our lungs," he said.

Hammes said the survey also covered the January 2025 wildfires in California, which highlight how these events have become a “year-round phenomenon” with major wildfires starting anywhere.

There has been some improvement in South-East Asia, with authorities in cities like Bangkok taking action to tackle air pollution, he exlained.

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“Bangkok is the best monitored city on Earth for air pollution,” he told me. “There are more than 450 validated air quality monitoring locations in Bangkok. The government is operating a fair share of these, and the rest are operated by private individuals.

“Awareness levels are tremendous and we’ve seen a 40% drop over the last four months in terms of pollution.”

A recent study by the American Lung Association highlighted the role community monitoring networks can play in raising awareness of air pollution.

Hammes said many monitoring networks are “community driven from the beginning” and they have helped “forced political will to take action”.

Dr. Aidan Farrow, a senior scientist at Greenpeace International said the new report reveals two competing realities: an air pollution crisis and the rise of communities, scientists and data working to meet the challenge, in a statement.

Dr. Farrow added the transparent data in the report is an essential tool for holding polluters accountable and securing a healthy environment for everyone.

Health Risks From Wildfire Smoke

A study published in February claimed wildfire smoke exposure may contribute to about 24,100 deaths a year in the U.S.

Chronic exposure to fine particles from wildfire smoke is linked to increased risk of death, even for people living far from active fires, according to the study.

The researchers found there was no “safe” level of long-term exposure to wildfire-related air pollution and smoke can travel thousands of miles, meaning people do not need to live near a wildfire to be affected.

“This study shows that long-term exposure to PM2.5 from wildfire smoke poses a growing and serious threat to public health nationwide,” said Min Zhang, first author and postdoctoral fellow at the Icahn School of Medicine at Mount Sinai, in a statement.

© Forbes