Le Figaro Lyon
Since last weekend, the metropolis of Lyon has been affected by an episode of fine particle pollution (PM2.5 and PM10). The drop in temperatures and the low mobility of air masses have produced a "lid effect" on the Lyon area, Nicolas Vigier, air quality engineer at Atmo Auvergne-Rhône-Alpes, explains to Le Figaro: "In winter, the air warms up at altitude thanks to the sun's rays. But these rays are not powerful enough to heat the air near the ground, so this cold air remains blocked by the warm air aloft and the pollutants emitted as well."
The rain that has been falling since Monday morning has not had the desired effect on reducing the number of fine particles in the air, the engineer continues. "We were optimistic yesterday (Sunday) about how things would turn out, but the particulate matter level remains relatively high this morning despite the rain. This was due to the accumulation of these fine particles during the night and the conditions that remained very stable." However, a movement of air masses during the night from Tuesday to Wednesday should significantly reduce air pollution, concludes Nicolas Vigier.
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Differentiated traffic implementation
To combat this episode of pollution, the Rhône prefecture has put in place a whole series of measures since Saturday, including the adoption of differentiated traffic prohibiting access within Lyon's low-emission zone to vehicles with a Crit'Air sticker higher than class 2. At the same time, the speed limit was temporarily lowered from 20 km/h on the roads to 90 km/h.
The distribution of emission sources by pollutant in Auvergne-Rhône-Alpes. ATMO AURA
These measurements can have a marginal impact on the "volume" of particles present in the air, the majority of which come from domestic heating, Atmo says in its annual summary. In fact, between 56% and 72% of PM10 and PM2.5 particles come from home heating. Transport is responsible for 9% of emissions, agriculture between 9% and 21% and industry between 11% and 9%.