Millions of people take the metro to work every day. But how safe is the air in the Paris metro? We spent eight months measuring the levels of heavy metals in the fine particles throughout the Parisian underground network and the outskirts in 332 metro and RER stations.

We also investigated the impact of its air vents on the surrounding neigbourhoods. These vents emit much more polluted air than ambient air and the most contaminating ones might be hidden among Parisian buildings.

Bastien Berthier, 42, is a metro conductor. Since he started this job, his health has been deteriorating. He believes the pollution of the subway is responsible.

Our studies support Bastien’s opinion. All metro and RER passengers are more exposed to heavy metals and the overall pollution level in the network is, on average, almost 5 times higher than the WHO thresholds. This excessive pollution is added to the ambient air of Paris which infiltrates the stations.

This new season of ‘Green Warriors’ investigates major global environmental scandals and confronts the industrial and political leaders implicated. Their investigations make headlines around the world.

Full Series


  • Year: 2024
  • Duration: 52 min
  • Production: Premières Lignes
  • Director: Mathilde Cusin, Martin Boudot
  • Available Versions: ENG, FRA
  • Country of production: France