It's a topic that is often discussed but never really solved: Air pollution in metro stations. Is it harmful to health? A recent study carried out in the Paris metro by Ile-de-France Mobilités (IDFM) and Airparif has produced a detailed overview of pollution in the metro and the Réseau Express Régional (RER) and identified three stations with worryingly high levels of pollutants.
Particulate matter produced when trains brake can cause respiratory problems or illnesses, especially in susceptible people. This study comes after an investigation by the Paris public prosecutor's office into RATP, the state-owned public transport operator, which is suspected of leaving its users in the dark about unusually high levels of particulate matter.
The study, which can be described as a large-scale investigation, was carried out in order to obtain reliable data. The IDFM asked the RATP and SNCF, the French national railway company, to carry out measurements around the clock for a week. Continuous measurements were also carried out in some stations over the period 2015-2022.
The results are worrying: three stations have a PM10 particulate matter concentration of more than 480 µg/m3. This exceeds the maximum value recommended by the French National Health Safety Agency (ANSES) for one hour of exposure. Unfortunately, no data is yet available for the finer and more harmful PM2.5 particles.
The Belleville, Jaurès and Oberkampf stations, all located in the east of Paris, are the most affected. Of the other stations analysed, 31 showed a PM10 particulate matter concentration between 140 and 480 µg/m3 and ten a "lower value", i.e. less than 140 µg/m3. The current EU limit value for PM10 is 40 µg/m3.
These results raise many questions, particularly with regard to the health consequences for passengers and employees. The RATP argues that the data does not accurately reflect people's actual exposure as no one spends a full hour on a railway platform.
In June, the IDFM will publish a full map of the 397 metro and RER stations and lines. It will be interesting to see whether the concentration of particles on the trains is actually lower than on the platforms, as suggested by IDFM Managing Director Laurent Probst.
In the meantime, the IDFM has asked the operators RATP and SNCF to draw up an action plan to improve air quality in the most polluted stations. Belleville and Jaurès are due to receive a new fan this year and a new fan has already been in operation at Oberkampf since the end of 2023.
The IDFM is also calling for the introduction of a system that reduces particulate emissions when trains brake. Only the latest MP14 series underground trains, which are used on lines 4, 11 and 14, already have an electromagnetic brake that does not emit particulate matter.
It remains to be seen whether these measures will be sufficient to improve air quality in the Paris metro. It is clear that the problem of air pollution must be taken seriously in order to protect the health of millions of passengers and employees.