The metro is not a very clean place, there is no doubt. But the inconvenience would not be limited to bad smells. Ultrafine particles in the Dutch metro are rich in metals, according to a study by researchers at the University of Southampton, UK and the Netherlands Environmental Health Center. These dusts can be very dangerous because they are toxic and, given their size, they can penetrate into the heart of cells and damage their DNA, which can develop cancer.
In the study, published on April 16 by the journal Environmental Science & Technology, scientists explain that the ultra-fine particles of the metro contain so-called “transition” materials, such as iron, copper, manganese, chromium or zinc. The reduced size allows them to enter the bronchi and exchange with the blood. They therefore pass into the circulation and can reach all organs of the body such as the heart and the brain. However, scientists admit their limitations regarding this research: “We do not know enough to be able to give recommendations regarding their cut-off rates,” says Matthew Loxham, co-author of the study.
In Paris, the RATP has been monitoring metro air quality since 1997 at three stations: Châtelet, Franklin-Roosevelt and Auber. Temperature, humidity and carbon dioxide levels are part of the data that is checked every hour. Ultrafine particles are only monitored irregularly. On its website, the RATP specifies that metal dust is produced by the braking system. The operator of the Paris metro is therefore committed to working on electric braking, which emits fewer particles.