CONCENTRATIONS OF AIRBORNE PARTICULATE MATTERS IN UNDERGROUND AND SURFACE STATIONS OF TEHRAN SUBWAY SYSTEM

Introduction: Air pollution in closed environments like underground subway stations has many severe effects on human health. This study was performed to investigate the concentrations of PM10 and PM2.5 in the air of platforms, office areas, and adjacent outdoor air of two stations in Tehran subway system. Materials and Methods: Sampling was conducted in April to September 2011 using a portable GRIMM dust monitor. Samples were taken from indoor air at each station from platform and ticket office area also from adjacent outdoor air of each station. Results: The concentrations of PM10 ranged from 33 μg/m3 at the office area of Imam Khomeini station to 160 μg/m3 at the outdoor air of Sadeghiye station. The PM2.5 concentrations varied from 10.9 to 97.7 μg/m3. Based on results of regression analysis the PM10 and PM2.5 concentrations at the platform of Sadegiye station are strongly associated with adjacent outdoor levels (R2 =0.77 and 0.67 respectively), while PM10 and PM2.5 concentrations in the platform of Imam Khomeini are less influenced by adjacent outdoor levels (R2 =0.36 and 0.4 respectively). Spearman's correlations were high for both platform PM2.5 and PM10, since the outdoor/indoor coefficient of PM2.5 was 0.58, whereas PM10outdoor/ PM10indoor coefficient was 0.62, indicating an important influence of outdoor particles introduced through the ventilation systems and by passengers. Conclusions: Results showed that there was a strong correlation between PM concentrations at platform of Sadegiye station (surface station) and outdoor air representing air quality in the platform of this station influenced by outdoor air.