Wildfires and Heatwaves Are Reversing Progress on Air Quality

Wildfires and heatwaves are making it harder to improve air quality, according to the World Meteorological Organization’s sixth Air Quality and Climate Bulletin. The report describes a connected threat: a warmer climate can increase the likelihood of intense fires and prolonged heat, while smoke and ozone pollution harm people and ecosystems and can add to climate pressures.

The pattern was visible in the bulletin’s assessment of 2025. Fine-particle pollution, measured as PM2.5, was higher than its long-term average in northern Canada, parts of Russia, western-central Africa and northwestern Spain, regions affected by significant fire activity. China recorded lower-than-average concentrations, while India’s levels remained above average. These differences show that air-quality trends are shaped by local emissions and weather as well as by broader climate conditions.

PM2.5 consists of particles small enough to penetrate deep into the lungs and, in some cases, enter the bloodstream. Wildfire smoke can contain a complex mixture of these particles and other pollutants. Health effects associated with smoke exposure include breathing problems, more hospital visits and greater use of medication. Research discussed in reporting on the bulletin also links exposure to mental-health impacts and poorer outcomes during pregnancy.

The danger is not limited to places where fires are burning. Smoke can travel across borders and oceans, carrying pollution far from its source. Research cited by the WMO indicates that extreme wildfire-smoke events have become about three times more common than they were in the 1990s. It estimates that wildfire smoke may have contributed to almost 100,000 additional deaths each year during 2010–2018. That figure is uncertain and may understate the total because smoke exposure is difficult to measure and its health effects can be distributed over long periods.

Heat brings a separate but related air-quality problem. Sunlight and high temperatures accelerate chemical reactions that produce ground-level ozone, a pollutant that can irritate and damage lung tissue. Ozone exposure is also associated with cardiovascular harm. During extended heatwaves, people may therefore face simultaneous stress from dangerous temperatures, smoke particles and ozone. Those risks can be especially serious for older adults, children, pregnant people and those with respiratory or heart conditions.

The relationship can also work in the other direction. Some wildfire pollutants, including black carbon, influence how much sunlight the atmosphere absorbs and how snow and ice reflect energy. Smoke can alter atmospheric conditions, while climate-driven fires release more carbon and other substances. The result is not a single simple feedback loop everywhere, but a set of interactions that makes climate and air pollution difficult to manage separately.

The bulletin warns that conventional pollution assessments may miss part of the damage. Standard models can underestimate deaths associated with wildfire smoke by as much as 93 percent in some analyses, particularly when they do not represent the distinct composition and spread of fire emissions well. Better monitoring is needed for PM2.5, black carbon and airborne microplastics, which remain insufficiently tracked despite their ability to travel widely.

This has practical implications for governments. Regulations that reduce pollution from vehicles, power stations and factories can still produce meaningful gains, but those gains may be weakened by increasingly severe fires and heatwaves. Meeting World Health Organization air-quality guidelines is likely to become more difficult as extreme fire conditions become more common. Warning systems, smoke forecasts, public-health advice and access to cleaner indoor air can reduce immediate exposure, while reducing greenhouse-gas emissions addresses one of the conditions driving the longer-term trend.

The central message is that clean-air policy and climate policy need to be planned together. Cutting routine emissions remains important, but protecting health in a warming world also requires stronger fire management, more complete observation networks and preparation for pollution that crosses national boundaries. The consequences of these decisions will be shared by communities far beyond the countries where the largest fires occur.

Sources: [World Meteorological Organization](https://wmo.int/media/news/wmo-bulletin-shows-air-quality-and-climate-interlinkages), [The Guardian](https://www.theguardian.com/environment/2026/sep/07/heatwaves-wildfires-setting-back-air-quality-improvements-un-finds), and [Reuters via Investing.com](https://www.investing.com/news/world-news/wildfires-heat-waves-threaten-to-undermine-air-quality-un-weather-agency-says-4890355).