Sn the small road that weaves its way between the rocky ridges and the valleys covered with maquis, only the fluty song of the blackbird accompanies the dawn that spreads over these vast moors of arid land. At the turn of the stony paths that penetrate these hills dotted with strawberry trees and heather, an ocean of greenery spread over more than 15,000 hectares between sea and mountains is revealed: the Agriates desert.
On the coast hugging the contours of the Gulf of Saint-Florent (Haute-Corse), these 37 kilometers of shores untouched by any construction and bordered by Posidonia meadows would almost make you forget civilization, if the frequentation of the beaches did not disturb this tranquility. , when summer arrives. Three days of walking are necessary to walk along these coasts, breathing deeply the scent of maritime pines, heather and myrtle, walking along these paths dotted with cistus.
“Here, it’s the great outdoors,” says Stéphane Poncé, a hiking guide who loves these places. Les Agriates is one of the greenest places in Corsica. Until the beginning of the XXe century, they were even one of the granaries of the island. It is not a desert in the traditional sense of the term, because the vegetation is abundant there. It’s just a human wasteland. These attributes are not unrelated to the quality of the air we breathe there.
Almost non-existent industrial fabric
In the “Point” ranking, the seaside resort of Saint-Florent, from where this maquis sanctuary extends, climbs to the top thirty places, among more than a thousand coastal towns listed across France. The average concentration in the atmosphere of fine particles of the PM 2.5 type is very low there. As the symbol of an island territory with clean air, which is one of the regions where one breathes the best.
READ ALSOEXCLUSIVE. The ranking of the cities where you can breathe the bestIn the “top 100” of seaside towns where pollution is the lowest, 55 are in fact located on the island. In Haute-Corse, for the vast majority of them. How to explain this singularity? According to Qualitair Corse, an association approved for monitoring air quality in the region, the reasons are to be found in a combination of factors: an almost non-existent industrial fabric, the distance from sources emitting pollution, a demography characterized by low population density – 39 inhabitants per square kilometer, nearly three times less than the national average…
“Corsica is a very rural region, with little industrial development and which, due to its insularity, is isolated from the European territories which are most suffocating, such as the Po plain in Italy, observes Jean-Luc Savelli, director of Quality Corse. Its geographical location is rather favorable to good air quality, despite a few black spots. »
The “black spot” of maritime traffic
This scientist refers to the pollution generated around the two agglomerations of the island, Ajaccio and Bastia. The main sources of nuisance are clearly identified. The density of road traffic has a lot to do with it around the main axes – more than 40,000 vehicles pass through each of the two large Corsican cities every day – as does the presence of the Lucciana and Vazzio thermal power stations, both of which run on fuel oil, at the entrance to towns.
Another “black spot”: maritime activity. Throughout the year, the five island ports welcome, on average, 5 million passengers departing from mainland France and Italy. Ecological associations are never very far away to denounce, through demonstrations on the quays, the environmental damage of these ships, cruise liners in the lead.
READ ALSOCantal, the least polluted department in FranceWith 473 stopovers, 2022 even served as a record year, in Corsica, for the reception of these “giants of the seas”. This is not the least of the paradoxes: if Bastia sees, each year, more than 2 million passengers and 54% of the island’s freight pass through its quays, making this basin the second French port in the Mediterranean in terms of of traffic, the city ranks 22e rank of the least polluted seaside resorts. It is even the second coastal town in France, following its close neighbour, Furiani, where the concentration of PM 2.5 in the air is the lowest.
“We are talking regarding an annual average for the whole city, which does not reflect the pollution peaks observed within the port enclosure in the summer period, when activity is at its highest, tempers Muriel Segondy, door -word of the association Le Garde, focused on the defense of the environment. If we place the particle detection sensors under the smoke plumes during the August rush, the analysis may be significantly different…”
Windy area
Scientists do not dispute the variations in pollution depending on the localities studied. For their part, Corsican shipowners claim to have accelerated their transition to more “green” boats, less greedy in fossil fuels and more efficient in environmental terms.
At the beginning of January, the maritime company Corsica Linea, public service delegate for maritime services to the island, took a further step towards the “decarbonisation” of its activities: the shipowner inaugurated a brand new vessel of 206 meters long, the first of its fleet powered by liquefied natural gas, on a regular line to the port of Marseille. According to the company, this odorless and non-corrosive fuel emits 20 to 25% CO2 up to 99% less sulfur and nitrogen oxide than other boats.
READ ALSOHow the air in our cities is improving“This investment completes the installation of smoke treatments on five of our ships to filter particles,” explains Pierre-Antoine Villanova, CEO of Corsica Linea. Six of our units – out of nine – therefore already comply with so-called Seca standards. [Sulphur Emission Control Area, NDLR] on sulfur discharges and atmospheric emissions, which will enter into force in 2025 in the Mediterranean. »
Recent efforts by shipowners are not enough to explain the paradox of Corsican port cities. The Qualitair Corse teams provide a completely different explanation: the impact of the weather, in several localities in the south or at the tip of the island where the wind blows more than 150 days a year.
“Corsica is one of the windiest areas in mainland France,” emphasizes Jean-Luc Savelli. Due to its geographical position, wedged between sea and mountains, to the south of a low pressure zone which forms on the Gulf of Genoa, Bastia presents, for example, a favorable situation for the dispersion of pollutants. The wind, which is sometimes intense, can carry the particles over long distances, which does not, however, prevent episodes of pollution depending on the air flows. »
The “green lung” of Vizzavona
The center of the island may well be much less ventilated than the coasts, but the quality of the air is not altered any further. On the contrary: the mountain villages that populate the interior – Riventosa, Santo-Pietro-di-Venaco, Noceta, Casanova, Venaco, Soveria, Focicchia… – occupy the first places in the classification of the Point.
In the heart of the verdant Corsica Regional Natural Park, the Vizzavona forest massif, which extends over 1,634 hectares of laricio pines, beeches and hollies, even ranks first among the ten French forests least polluted by fine particles. . Far ahead of the forests of Tronçais (Allier) and Iraty, the largest beech forest in Europe, clinging to the Pyrenees, between France and Spain.
READ ALSOAir pollution: the hidden health crisisAccording to Qualitair Corse, the burning of firewood in the residential sector and the burning of plants are the main factors here that alter the ambient air. The phenomenon is nonetheless minor in view of the demographic decline and the weakness of the economic fabric in the center of the island. Doctors have also detected, a long time ago, the virtues of this haven of freshness: since 1963 is established in the village of Vivario, on the foothills of the forest massif of Vizzavona, the only sanatorium of Corsica, an establishment specializing in the treatment of pulmonary tuberculosis.
A choice that was not dictated by chance: “The sanatorium was installed in the heart of Vizzavona because the air was pure and reputed to be favorable to this care, advances Venture Selvini, the mayor of Vivario. Apart from the main road that crosses the town to connect Bastia to Ajaccio, the sources of pollution are, following all, relative. We can, of course, always reduce pollutant emissions, but the forest remains a veritable green lung prized by city dwellers, who come to recharge their batteries there, because it is a preserved place. Nothing is ever perfect, but when we compare ourselves, we are reassured…”