Impact of train braking systems on particle levels in the Paris subway

摘要

Several factors can explain the high levels of particle concentrations inunderground transportation systems. One of the main particle sources is train’smechanical braking system. The mechanical braking is decreasing with therenewal of rolling stock, new trains have other brake kind: the electrodynamicbraking. This technology decreases the mechanical braking use and this one ismore and more efficient on new trains.Two stages have been planned to study the brake technology (with electrodynamicbraking //without electrodynamic braking) on particulate air pollution. PM2.5mass concentration and PM10 mass concentration were simultaneously measuredat Colonel Fabien subway platform. The chemical composition of the fine particlefraction (PM2.5) and the coarse fraction (PM10-2.5) is measured using PIXEanalysis.In this campaign, the brake technology has an impact on the air quality. Theelectrodynamic braking use lowers the PM10 mass concentration by a factor of4.3. Moreover, the train’s mechanical braking system is responsible for a higheriron mass percentage in the coarse particle fraction.