in Paris, schools always above health standards

What levels of air pollution are children exposed to? Parisians when they are at school? In March 2019, The world had published, with the association Respire, a first map of schools in Paris. This unprecedented mapping revealed that the concentrations of pollutants measured in the immediate vicinity of schools (from nursery to high school) often exceeded, and sometimes in worrying proportions, the limits recommended by the World Health Organization (WHO). The mayor of Paris, Anne Hidalgo, then undertook to play the card of “Full transparency” and to launch a “Pollution measurement campaign in the courtyards of nurseries, schools and colleges”.

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The results of this campaign were presented Tuesday, May 4, at the end of the day, to teachers and parents’ representatives of the establishments concerned by this experiment. Carried out by Airparif, the body responsible for monitoring air quality in Ile-de-France, the study focused on 44 nurseries, schools and colleges identified as hot spots on the Respire map. For one year, from September 2019 to September 2020, several measurement tools – including 140 microsensors funded by Bloomberg Philanthropies – were installed in the courtyards and adjacent streets, in addition to the 16 automatic reference stations of the Airparif network.

A “screen effect” of the walls

Two pollutants were monitored: nitrogen dioxide (NO2), a toxic gas emitted mainly by road traffic and in particular by diesels, and fine particles (PM2.5, less than 2.5 micrometers), the most dangerous for health because they penetrate deeper into the body. As a preamble, Airparif notes that the levels recorded are most certainly underestimated: some of the measurements were carried out during confinement, a period marked by a historic drop in NO emissions.2 (up to -60%), linked to that of automobile traffic.

It prevents. Regarding exposure to NO2, the results of the experiment will certainly reassure the parents of the pupils. The levels measured in all the courtyards are below the WHO thresholds (40 µg / m3 on annual average), even if some are approaching it, as in the case of the Pyrenees nursery (36 µg / m3), in the 20e borough. The study also shows that they decrease significantly depending on the distance from the nearest road axis: the concentrations recorded in the courtyards are on average 36% lower than those measured in the streets adjacent to establishments. . Airparif highlights a “Screen effect of buildings and walls” . Moreover, the only establishment where the levels of NO2 are equivalent between the street and the courtyard (the Etienne Marcel school, in the 2e arrondissement) does not have a dividing wall.

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