“A simple butt can be devastating”: a fire in Mediterranean vegetation can spread at a speed of 5 to 8 km/h

Luc Langeron, directeur prévention de l’Entente Valabre. Jean-Michel Mart – JEAN-MICHEL MART

Luc Langeron, prevention director Entente Valabre, a public establishment bringing together 15 departments in the south-east in the fight against natural risks, explains why throwing a cigarette butt out of your car window is not so trivial.

Throwing your cigarette butt out of your car window can really cause a fire ?

Smokers do not know it or are not aware of it, but the risk is real, we have demonstrated this during tests carried out in our laboratory. With the breath of cars and a wind, even a light one at 30 km/h, a cigarette butt is very quickly pushed from the road onto dry grass. However, if there is low humidity (the amount of water vapour contained in humid air, Editor's note), and this is the case all summer, the flammability of the vegetation is high. This is normal, grasses finish their cycle in the spring and if there has been no rain, they are particularly dry. All of this is a maximum risk factor for the cigarette butt, the incandescent part that reaches up to 800 degrees and can take several hours to burn, to start a fire that can be devastating. After the grass, it will spread to the bushes, then to the branches and trees at a speed of 5 to 8 km/h.

Is Mediterranean vegetation even more sensitive to the risk of fire ?

Of course. We are in a region where plants are adapted to drought. In fact, they have a low moisture content and are therefore very combustible, very flammable. The slightest spark, the slightest source of heat can ignite it. But there is no spontaneous generation of fire in the forest. In the vast majority of cases, it is carelessness or intentional ignition that causes a fire.

How many fires of this type start in the Mediterranean arc each year??

Between 3,000 and 5,000 wildfires and fires in peri-urban areas each year. This figure is falling slightly, but it is clearly not enough, especially since 90% of them are located along traffic routes or near homes, which supports the theory of human intervention. Each fire is also the subject of an investigation and the cigarette butt is the cause in 15 to 20% of careless acts.

Isn't it absurd to have to remind people again that you should not throw your cigarette butt in nature??

Unfortunately yes. But it's the same thing as for driving behavior. If there is a white line in the middle of the road, it is not for the pleasure of painting it and yet, people still cross it. There is not an accident for every carelessness, but behind a carelessness, there can be an accident. It is the same for the cigarette butt thrown out the window. We do not stigmatize all smokers, they do not all act in such an inconsiderate manner, but the observation of the number of cigarette butts thrown on the roads and of fires starts obliges us, again, to hammer home this message of prevention.

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