Metro systems in French cities have up to three times as much fine particle pollution as the outside air, according to the French National agency, which says that improving air quality in public transit should be a key focus for France’s public health policy.
The Anses health safety agency looked at pollution levels in seven underground transport networks, including the Paris area metro, and the Lyon, Marseille, Lille, Toulouse, Rennes and Rouen systems, and found that fine particle pollution is “on average three times higher than in the urban exterior air”.
In a report published Wednesday, the agency said the particles have “a high amount of metallic elements, iron in particular, and also of elemental and organic carbon.”
The pollution is caused by the rubbing of breaks against the metal rails, and the particles are pushed into the air by trains moving through tunnels.
The agency says that there is not enough data to show the health effects on passengers of this pollution, but it says data “suggests the possibility of cardio-vascular effects, inflammation and oxidative stress”.
Given that public transport is being pushed as an alternative to cars, to reduce CO2 emissions, the agency stresses that the metro systems must expand what are currently only piecemeal efforts to measure and improve the air quality, in stations, on platforms and in the train cars themselves.
Measuring exposure to the pollution must take into account the length of time people spend underground as they go about their daily commutes, and the accumulated exposure must respect exposure levels set by the European Union in 2008, and if possible, stricter norms put in place by the World Health Organisation.
In the Paris metro system, pollution is only measured on platforms, whereas it should also be measured in hallways and in train cars.
To improve air quality, trains must be replaced and break systems upgraded to avoid the creation of fine particles, and ventilation should be improved.
Ile-de-France Mobilités, which manages the Paris metro and the suburban train system, put in place an action plan in May, with tests on new break systems and 57 million euros of investment into ventilation.
The RATP, which exploits the paris metro, was sued in 2021 by an NGO and representatives of metro users, for involuntary harm due to air pollution in the system, and for fraud, for not disclosing pollution levels to users.