As large fires burn out of control across parts of Europe and North America this summer, the smoke they generate travels further – across countries and even continents – exposing millions to harmful air pollution.

WHO warns that climate change, prolonged heatwaves, drought and changing land management practices are increasing the frequency and intensity of wildfires, making smoke exposure a growing public health concern.

Although many wildfires are caused by human activity, climate change is creating hotter, drier conditions that allow fires to ignite more easily and spread more rapidly. Because smoke can travel vast distances, poor air quality can affect communities far from an active wildfire for days or even weeks.

Harmful effects

Wildfire smoke is a complex mixture of gases and fine particles released when vegetation, buildings and other materials burn. Fires that spread into urban or industrial areas can release additional toxic pollutants.

One of the greatest concerns is fine particulate matter (PM2.5), which can penetrate deep into the lungs and enter the bloodstream.

Exposure can cause coughing, eye and throat irritation, headaches, wheezing and shortness of breath, while worsening asthma and other chronic conditions.

Infants and young children – whose lungs are still developing – older people, pregnant women, people with disabilities and those living in poorly insulated homes are among the most vulnerable to smoke exposure.

Emergency responders and outdoor workers also face heightened risks because of prolonged exposure. Wildfires also take a psychological toll, contributing to stress, anxiety and trauma during and after emergencies.

Reducing exposure

WHO is urging people to monitor air quality alerts and follow official advice, even if fires are not nearby.

“When wildfires are present in your area, even if some distance away, follow instructions from your local authorities, who will have the most up to date, on-the-ground information,” said Dorota Jarosinska of WHO's European Centre for Environment, Climate Change and Health.

“If you can smell smoke, it’s present in the air you’re breathing, and you should protect yourself by reducing your exposure, especially if you are in an at-risk group.

“Even if you can’t smell smoke, you may experience symptoms, and wildfires can change direction suddenly if winds shift, so stay alert for updates.”

During periods of heavy smoke, you should stay indoors with doors and windows closed – unless you are advised to evacuate.

If going outside is unavoidable, a well-fitting FFP2 or N95 mask can help reduce exposure.

Those with heart or lung conditions, pregnant women and anyone experiencing breathing difficulties should seek medical advice promptly.

Growing risks

WHO says protecting communities requires more than firefighting alone. Early warning systems, timely public health advice, access to medical care and clean-air shelters for vulnerable people are all essential.

The agency is working with countries across the European Region to strengthen preparedness for wildfires and heatwaves, helping health systems respond as fire seasons become longer, more frequent and increasingly severe.