For eight months, dozens of these volunteers equipped themselves with measuring tools during their daily journeys in order to establish the level of pollution on the RATP network, and compare it with that of outdoor air. This fine particle pollution comes both from the polluted air in the streets, which ventilate the stations, and from the metro trains themselves, which create dust during braking.

On average, the pollution of fine particles PM2.5 (diameter less than 2.5 micrometers) in the metro and RER is 24 μg / m3, nearly five times more than the 5 μg / m3 recommended by the WHO, details in a statement Monday "Green of rage", a program broadcast on France 5 that investigates environmental scandals.

Over-pollution, defined as excess pollution in the station compared to the outdoors, was measured at 10.5 μg/m3 on average.

The study was coordinated by Jean-Baptiste Renard, director of research at the CNRS and member of the scientific committee of the association Respire, at the origin of a complaint that led in April to the opening of an investigation against the RATP for "endangering others and deception".

This work has not been published in a scientific journal, but is in addition to others carried out using various methods over the years.

A year ago, the National Agency for Health Security (ANSES) considered that "the corpus of specific epidemiological and toxicological studies (was) too limited to be able to draw firm conclusions on the possible health effects of users' exposure to air pollution", but it noted that existing data suggested "the possibility" of cardio-respiratory effects.

"Such measurements must be carried out according to validated scientific protocols and with reference material," RATP told AFP via its head of the sustainable development department, Sophie Mazoué, questioning the method and devices used by the Vert de rage study.

RATP says it is implementing measures such as air renewal devices and brake linings to reduce risks.

Proof of the actions carried out and their effectiveness: an epidemiological study conducted over the period 1980-2017 which "does not show an increase in respiratory and cardiovascular symptoms among our employees", insists the Régie.

The study carried out by "Vert de rage" established a ranking of the most polluted stations and lines, led by line 5, "where the average over-pollution generated by traffic" is 18 μg/m3.

© 2023 AFP