Assessment of Coarse, Fine, and Ultrafine Particles in S-Bahn Trains and Underground Stations in Stuttgart

The Stuttgart S-Bahn network comprises six subway lines and is used by approximately 425,000 people on a daily basis. In previous studies in other cities, it was found that subways can be source collection point of particulate matter (PM), which detrimental to human health. This study focused making an initial assessment the pollution situation inside trains underground platforms. Real-time measurements were performed with high time-resolution instruments trains, two stations, outdoor stations November 2019. Firstly, variation concentration train as traveled through tunnel investigated, recurrently observed pollutant increased while traveling then decreased when nearing exit. Secondly, measurement location highest concentrations determined. platforms higher than those addition, dominant fraction measured range ultrafine particles (UFP). Finally, wind speed direction data analyzed conjunction specific locations along From results, assumed combined airflows led particle resuspension these areas. conclusion, determined users exposed concentrations, particularly UFP (10–116 nm), standing tunnels. It PNCs wagons well PM BC mass increase passing tunnel. Additionally, average number UFPs significantly factors around 1.7 1.9 for 1.6 2 coarse fine particles.