Evaluation of the concentration of suspended particles in underground subway stations in Tehran and its comparison with ambient concentrations

Subway lines are responsible for 20% of the total passenger traffic in Tehran. Particulate matter is one most important major pollutants subway stations and increasing their concentration leads to numerous health consequences passengers employees. This study aims investigate PM10 PM2.5 four underground metro compare them with these particles open air. Seasonal sampling (April 2018 - April 2019) particulate matters was conducted middle months all seasons week each season at peak times from 8am 12am, three locations (entrance, middle, exit station) also outside ambient station. The results then compared relevant standards. main sources suspended were due traffic, train piston pressure, floor cleaning, maintenance operations, wheel-rail wear braking, performance ventilation system monitoring measurements this showed that annual average concentrations 68 μg/m3 47 outdoor around 42 29 μg/m3, respectively. Also, stations, 1.5-1.7 higher than those ambient,