Investigation on the Concentration of Suspended Particulate Matters in Tehran Underground Subway Stations and Compare it with Ambient Concentrations

Metro lines are responsible for 20% of the total passenger traffic in Tehran. Particulate matter is one of the most important major pollutants in subway stations and increasing their concentration leads to numerous health consequences for passengers and subway employees. The aim of this study was to investigate the concentration of PM10 and PM2.5 in four underground metro stations (Azadi, Enghelab, Tohid and Vali Asr) and compare them with the concentration of these particles in the open air. Research

Seasonal sampling (April 2016 - April 2017) of particulate matters was conducted in the middle months of all four seasons for one week in the middle months of each season at peak traffic times from 8 am to 12 am, at three locations (entrance, middle, and exit in each station) and also at outside ambient of each station. The results were then compared with the relevant standards.

The main sources of suspended particulate matter in the underground subway stations were due to passenger traffic, train piston pressure, floor cleaning, maintenance operations, wheel-rail wear and braking and the performance of ventilation system in the subway station. The results of the monitoring measurements in this study showed that the annual average concentrations of PM10 and PM2.5 in the four underground subway stations were 68 µg/m3 and 47 µg/m3 and in the outdoor ambient around these stations were 42 and 29 µg/m3, respectively.  

The results of this study showed that in the four underground subway stations, the annual average concentrations of PM10 and PM2.5 were 1.5 - 1.7 times higher than those in the outdoor ambient, respectively.