Why Wildfire Smoke Is Different from Everyday Air Pollution?

Wildfire smoke can travel hundreds of kilometres. Here's what makes it different from the air pollution we breathe every day.

Wildfire smoke does not only affect people living close to the flames. Its particles can travel hundreds of kilometres, exposing people to elevated levels of air pollution even in cities and regions far from the fire. Although wildfire smoke and urban air pollution share some common pollutants, they differ in their chemical composition. Growing scientific evidence suggests that these differences may also influence their effects on human health.

Why Wildfire Smoke Deserves Special Attention?

Wildfire smoke is not simply "dust" or soot. It is a complex and constantly changing mixture of gases and fine particulate matter (PM₂.₅), carbon monoxide, nitrogen oxides and volatile organic compounds. Its exact composition depends on the type of vegetation that burns and the combustion conditions.

Wildfire smoke is not simply "dust" or soot. It is a complex and constantly changing mixture of gases and fine particulate matter (PM₂.₅), carbon monoxide, nitrogen oxides and volatile organic compounds.

This complex chemical composition means that the toxicity of wildfire smoke varies from one fire to another. In addition to its unique chemical composition, wildfire smoke often leads to extremely high concentrations of air pollutants over short periods of time. During severe wildfire events, PM₂.₅ levels can exceed air quality guidelines, exposing large populations to hazardous pollution levels.

What is happening in Spain?

Spain is among the European countries most exposed to wildfires. As global temperatures rise and climate change drives more dry weather condition, the risk of wildfires is increasing in Spain and much of Southern Europe, making exposure to wildfire smoke a growing public health concern.

Average annual exposure to wildfire-related PM₂.₅ is highest in regions such as Galicia, Extremadura, the Valencian Community, the Region of Murcia and Andalusia. Although wildfires can occur at different times of the year, smoke-related air pollution typically peaks in July and August, coinciding with heatwaves.

What does the evidence show?

A study conducted as part of the CATALYSE Horizon Europe project led by ISGlobal and published in The Lancet Planetary Health, analysed the impact of wildfire smoke across Europe between 2004 and 2022.

The study estimates that short-term exposure to wildfire smoke caused an average of 535 deaths per year across Europe. It also shows that treating PM₂.₅ from wildfire smoke as equivalent to PM₂.₅ from other sources like traffic would substantially underestimate its impact on mortality.

Treating PM₂.₅ from wildfire smoke as equivalent to PM₂.₅ from other sources like traffic would substantially underestimate its impact on mortality.

The most immediate health effects are observed in the respiratory and cardiovascular systems. Children, older adults, pregnant women and people with pre-existing health conditions are particularly vulnerable, with emergency department visits increasing during wildfire smoke episodes.

How to protect your health during a wildfire smoke episode

Precautions recommended by Spain's Ministry of Health to protect yourself from wildfires and wildfire smoke include:

• Stay indoors, keeping windows and doors closed to prevent polluted air from entering.
• Wear an FFP2 or N95 respirator if you need to go outside. Surgical and cloth masks do not effectively filter fine PM₂.₅ particles.
• Stay well hydrated by drinking plenty of water and avoiding alcohol and caffeinated drinks.
• Follow official air quality alerts and the recommendations issued by public health authorities.