Numerous episodes of pollution have affected Corsica since the start of the year. More than usual ? And whose fault is it? Answers and explanations
Clouds of fine particles from the desert, a sky of ashes, those of the fires of the Var, which plagues the island, alerts of Qualitair which seem to multiply since the beginning of the year. Say uncle, why are you coughing?
READ ALSO: The fires in the Var cause air pollution in Corsica
To answer, we could start with figures, those of the Qualitair Corse association, responsible for monitoring air quality in the region. On the clock, a little more alerts, 6 since the start of the year against 4 in 2018 and 2019.
Relentless? Not necessarily for Jean-Luc Savelli, at the head of the association. “We have changed the way we work. Before, there was the observation and then the triggering of the alert. Today we have other elements and an upstream forecast. So we trigger more often because we can more predict. “
Fine particles from the Sahara, then from the Var fires? ” There are years when we have 2 episodes, others 5 … What we can project in relation to the elements carried by the IPCC, with the advance of the desert, the warming, is that there will be maybe more episodes in the future. But for now, it’s not confirmed “. Over the past 15 years, he continues, “ we are not witnessing a deterioration in the quality of the air in Corsica ”. Jean-Luc Savelli even mentions “Some improvement in the cities”.
Imported or “made in Corsica”
On the side of Météo France, Patrick Rebillout, director of the island center, also remains cautious. “We had a few episodes in Saharan dust. These are known phenomena. Are they increasing? We have nothing very solid about it. Should we attribute them to climate change? Nothing very robust either. To be continued. We must take into account the variability of the climate. Nothing is linear. But the aridity that is developing will generate more dust, that’s for sure ”.
Located in the middle of the Mediterranean, Corsica can only “endure” the many currents which drain masses of air. Ozone arrives from the Po Plain (in Italy). ” We received smoke from the fires in the Var and, in addition, they remained, specifies the meteorologist. Corsica is not safe but there is also local pollution in addition to exogenous pollution ”.
Jean-Luc Savelli insists, distinguishes two territories. The rural, first of all, and overall, a very good mention, “With the exception of a few external elements”, he notes before citing, too, the chemical pollution descending from the southern zone of France, from the Plaine du Pô, from the pond of Berre.
READ ALSO: The sand clouds of the desert observed with a magnifying glass by Qualitair Corse
It also evokes the anticyclones which turn, the flows which go up towards the island and, “It’s quite classic”, particles of the desert are loaded with them. “In these clouds, we find sand that we can clearly see on cars or laundry. On the other hand, there are finer particles in this cocktail. And even if it’s sand, they can have health impacts. Imagine if the cloud passes over industrial sites in Tunisia … “
Pollution, it would not be us, it would be the others. Except that, in the second territory, the urban, ” let’s meet, recognizes the director of Qualitair Corse, in classic situations that exist here as elsewhere. First, there is the road, heavy congestion. You just have to look at the traffic jams in Ajaccio and Bastia. In our jargon, a busy road is 10,000 vehicles. At the entrance to Bastia, it’s 50,000! The roads are not suitable, and in city centers, with small streets wedged between buildings on either side, there can be no dispersion of pollution ”.
The car fleet has certainly improved a little with more recent vehicles, ” a positive point. But the negative point is that the renewal is done with bigger cars ”. The famous SUVs. As a result, declining annual averages in city centers are now starting to stagnate, or even start to rise again.. Not too well preserved on this side, therefore, the island can reach levels equivalent to those of other medium-sized towns in France. And if we add the ports and their large ships, we get a thermal power station in Ajaccio …
Homemade
« On a small area, Corsica is affected by many sources of emissions ” and it presents, moreover, a particularity of the south of France: more local pollution, more difficult to evaluate. “Here, it is the burning of plants and, very locally, significant levels of pollution. We often quote the Gulf of Ajaccio, the south of Bastia as well. And that, we do not take them into account in the context of the forecast. It is impossible to anticipate. The message is still difficult to get across. We must recover the plants. During the first confinement, the pollutants linked to the road dropped significantly. Without creating better air quality. The stability was due to the activities of gardens and the numerous fires. “
However, burning is a “Incomplete combustion, pieces remain. Which emits more harmful pollutants. For years we said to each other ‘‘We burn something natural, it has no impact’. It’s wrong ! We saw it on a large scale with the fires in the Var. We are far enough away, but the concentrations were very high, so nearby … A fire in the neighbor’s house is 5 to 10 times more pollution than Var smoke ”. Self-produced pollution, therefore, home production as well. In the viewfinder, more and more isolated interiors that suffer the harmful effects of interior fragrances, paints, certain woods.
Work was therefore carried out with municipalities to assess the air quality in places open to the public such as nurseries, schools, and another with the construction industry. Objective: to do better, again.
Smoky
A veil of smoke descends on the island, coming from the Var lands on fire. The episode that hit Corsica on August 17 marked. Exogenous pollution, clearly visible. And especially harmful.
“The aerosols found in the air are classified according to the size of the particles that compose them: PM10 for sand, but also smaller ones such as PM 2.5 or even PM1 (soot). is what we have during fires like those in the Var and they are more dangerous than those found in urban pollution “, insists Toussaint Barboni, lecturer at the University of Corsica, particularly attached to the structuring forest fire project. Very toxic particles, very fine ” CMP ” compounds for ” carcinogens, mutagens and toxic for reproduction ” which can therefore penetrate very deeply into the human body.
“There are plumes of smoke over South America, Africa and they circulate all year round, at very high altitudes. Their impact is less on the island.”, continues the academic. But if fires in Europe have declined over the past 40 years with variations linked to the heatwave, the trend could be on the rise again with climate change. “And fires in the Mediterranean can impact Corsica.”
The vicious circle is indeed launched. “Climate change is causing even more fires. And with the greenhouse effect, these fires accentuate the latter.” Only one “spark” is missing, the heat wave, and the fear that the flames will devastate, this time, the island lands. “Corsica is the first wooded region in France (58% of the territory) and this fuel load has continued to grow with the abandonment of agricultural land”. Attention danger.
READ ALSO. The Mediterranean, hotspot for climate change
The diameter of a hair
Did you say fine particles? “It’s all that we will find in the air in solid or liquid form”, explains Jean-Luc Savelli, director of Qualitair Corse. Nothing gaseous, the letters PM for “Particulate matter” in English and the numbers corresponding to the particle size.
10 is 10 micrometers or 1 millionth of a meter or even 1 thousandth of a millimeter. “This corresponds to the diameter of a hair and these particles will not be stopped by the respiratory system. They will enter the body, go deep, see penetrate into the blood. This is what we also work for. with the ATMO index which takes into account PM 2.5 and below. “
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