The question is often raised, without ever being resolved. Is the air in the Paris metro dangerous for your health? For the first time, precise mapping of pollution in the Paris metro and RER was carried out at the initiative of the transport organizing authority Ile-de-France Mobilités (IDFM), with the support from Airparif, revealing high pollution levels in at least three stations.
Indeed, the concentration of fine particles, produced when trains brake, can cause respiratory difficulties or illnesses, particularly among vulnerable people.
Last spring, the Paris prosecutor’s office opened an investigation for “endangering others” targeting the RATP, suspected by the Respire association of hiding an abnormally high level of fine particles from its users.
A map of pollution in the Paris metro and RER
© / Ile-de-France Mobilités (IDFM)/Airparif
A real major study
To have reliable data, IDFM decided to carry out a large-scale study, with the support of Airparif, by asking the RATP and the SNCF to take measures at least for a full week seven days a week, 24 hours a day. In certain stations, measurements were taken continuously throughout the 2015-2022 period via the RATP and SNCF measurement network.
As a result, three stations display a concentration of fine PM10 particles exceeding 480µg/m3, i.e. the maximum threshold recommended by the National Health Security Agency (ANSES) from one hour of exposure.
No figures on PM2.5 particles, which are finer and more harmful, have been communicated at this stage.
Complete mapping in June
The threshold for PM10 is established by ANSES with regard to the exposure time in railway enclosures. The WHO recommends a maximum threshold of 140µg/m3, but this concerns exposure to open air. The stations concerned are Belleville, Jaurès and Oberkampf, all located in eastern Paris. Among the other stations studied, 31 display a “medium level” of concentration of fine PM10 particles, that is to say between 140 and 480µg/m3 and ten a “low level”, therefore less than 140 µg/m3.
Another study carried out for the television show “Vert de Rage” last year, but contested by the RATP, also came to the conclusion that the Belleville station was the most polluted.
“The work communicated by Airparif and IDFM does not reflect the exposure of travelers or employees,” says Sophie Mazoué, sustainable development manager for the RATP group. According to her, no user or employee stays on a platform for an hour, and data should also be available in the trains.
This will be the case in June since IDFM has promised to establish a precise map of the 397 metro and RER stations as well as the lines. “The particles are not the same in the trains and on the platforms. In general, it is a little lower in the trains because the air is ventilated. We will have the verification in June,” indicated the director general of IDFM, Laurent Probst.
Inflammation of the respiratory tract
At this stage, the very limited scientific literature on air quality in the metro prevents us from issuing a clear opinion on the consequences for health. ANSES suggested the risk of “inflammation of the respiratory tract, particularly in sensitive populations such as asthmatics” or “effects on autonomic cardiac function”. She rejected “the increased risk of lung cancer or myocardial infarction”.
In the meantime, IDFM intends to ask RATP and SNCF operators to deploy an action plan to improve air quality in the most polluted stations.
“The Belleville station will benefit from the renewal of a fan from 2024,” promised IDFM. Jaurès will see its fan reinforced this year and in Oberkampf, a new fan has been operating since the end of 2023 and two additional structures will be built this year. “These three stations will go at least orange, if not green,” Laurent Probst wants to believe.
IDFM also asked to deploy “as quickly as possible a system which reduces emissions of fine particles generated when trains brake”, particularly on the RER A and 1, 2, 3, 4, 5 and 9 metro lines. . At this stage, only the latest generation MP14 metros, deployed on lines 4, 11 and 14, have electro-magnetic braking, which does not emit fine particles.