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What are the effects of forest fires on population health?

With droughts and heat waves on the increase, fires are becoming more and more frequent in France. Fires produce gases and particulate emissions that impact population health, particularly for firefighters, who are the most exposed group. This article explains why.



    hectares of forest,  France has the third largest forest cover in the European Union. Forest areas vulnerable to fires are mainly located in the southern half of the country. These are mostly maquis and garrigue scrubland around the Mediterranean basin and in Corsica, and Landes pine forests in south-western France. As a result of climate change, northern regions are also at risk.

    What factors promote the spread of forest fires?

    The factors that have the greatest influence on wildfire and smoke behaviour are:

    • the terrain, particularly topographical and land-use aspects, and
    • the weather, including wind patterns and temperature inversion. 

    This means that fine particulate matter is easily transported over long distances, even up to several hundred kilometres.


    What is there in wildfire smoke?

    The composition of smoke depends on vegetation type, humidity, combustion conditions and the distance from the source.

    In areas affected by smoke from forest fires, suspended particles are the most significant air pollutant. Around 80% are fine particulate matter, most of which are submicron particles, smaller than one micron. Intense fires also generate giant ash particles.

    Carbon monoxide is also one of the major pollutants produced by wildfires.

    A large number of other chemicals, including carbon dioxide (CO2), volatile organic compounds, such as acrolein, formaldehyde and benzene, semi-volatile compounds, such as polycyclic aromatic hydrocarbons (PAHs), and heavy metals and nitrogen oxides (NOx), have also been identified as smoke components.

    Some pollutants from wildfires may also settle, spread or undergo chemical changes leading to contamination of soils and water resources.


    What are the health effects of fires and fire smoke?

    In the short term, inhaling smoke can cause respiratory effects such as respiratory tract irritation. This is linked to visits to accident and emergency services and hospital admissions due to respiratory disease, such as asthma or another chronic lung disease, or even to a change in lung function.

    In addition to respiratory effects, wildfire smoke can cause cardiovascular effects.


    Are some people more affected by wildfire smoke than others?

    Firefighters are the group most likely to suffer from the health effects of fires. They are faced with dangerous fire smoke:

    • directly when fighting a fire,
    • indirectly when monitoring, investigating or clearing up after a fire has been suppressed, and when returning to the fire station through exposure to equipment and vehicles contaminated by soot and firewater. 

    Moreover, people with chronic respiratory disease, including asthma, are particularly sensitive to forest fire smoke, as are people with cardiovascular disease.


    What should you do if you live in an area exposed to wildfire smoke?

    Everyone in non-evacuated areas reached by smoke plumes from a wildfire should follow these recommendations:

    • limit travel and time spent outdoors,
    • keep doors and windows closed and air out your home only when conditions are safe,
    • seal air gaps and vents with damp cloths,
    • stop controlled mechanical ventilation (CMV) when there is smoke,
    • avoid exercising outside when the air in the vicinity is smoke-filled,
    • keep the air inside your home healthy by not lighting incense or candles, etc., and
    • keep an eye on sensitive people.

    Sensitive individuals, i.e. those with a history of respiratory issues such as asthma, chronic respiratory failure or other respiratory or cardiovascular diseases must:

    • wear a filter mask, such as an FFP2 mask, if directly exposed to smoke, and
    • contact their general practitioner if experiencing respiratory symptoms or discomfort, or call 15 if these symptoms are severe.