Background and purpose: Particulate matter is one of the main pollutants in underground transport systems.  Increase in its concentration leads to health problems in passengers and metro staff. Current research aimed at studying the concentration of particulate matter with aerodynamic diameter less than 10 micron (PM10) in Tehran underground transport system.
Materials and methods: In this study, concentrations of PM10 were measured in 18 over ground stations and two underground stations during one month in autumn. Sampling was done three times a day (morning, afternoon, and evening) at the beginning, middle, and end of the platforms and the ticket hall. A portable Real-Time Direct Reading Particulate Monitor (HAZ DUST EPAM 5000) with a flow of 4 liters per minute was used. We studied the effect of depth of stations, number of passengers in stations and, number of trains on the emission of PM10 concentration.
Results: The results showed that average concentrations of PM10 in underground and over ground stations were 17.23±33.64 and 14.41±21.60 µg/m3, respectively. The concentration of pollutant were found to be higher at noon (8.25±32.01µg/m3), beginning of the platforms, and ticket halls (3.28±29.8 and 12.82±39.91 µg/m3, respectively).
Conclusion: This study indicated that the average concentration of particulate matter in Tehran underground transport system was lower than the standard levels accepted by the Environmental Protection Agency and the Department of Energy.