Exposure and dose to particulate matter inside the subway system of Athens, Greece

Real-time PM10 mass concentrations were monitored inside the trains and in several platforms of red and blue lines in Athens metro system during two measurement campaigns. Furthermore, measurements of PM1, PM2.5, and PM10 concentrations were conducted on a fixed site on a subway platform of blue line (Nomismatokopio) and the majority of particles were in the fine mode. PM10 concentrations were measured inside the metro trains along the entire route of the two metro lines during commuting hours, and the average PM10 concentration was 132.2 ± 34.0 μg/m3 in the red line and 138.0 ± 35.6 μg/m3 in the blue line. Measurements were also conducted in eight platforms and higher concentrations were observed in stations located in the center of Athens, under heavily trafficked streets. An exposure and dose assessment model, ExDoM2, was implemented in order to calculate the deposition, dose, and retention of aerosol particles in the respiratory tract (RT), the gastrointestinal (GI) tract, and their absorption to blood. The model was applied to study the human dose of three different subjects, a person with sedentary employment commuting by metro 1 h per day, a metro worker with sedentary activity, and a metro worker with light exercise activity. The dose varies in the different regions of the RT with the highest dose in the extrathoracic region. The dose in the RT after commuting by metro for 1 h was 125.4 μg that corresponds to 36.3% of the total personal daily dose (worst-case scenario, no indoor sources).