Risk assessment of PM2.5 exposure for passengers in subway stations

Ten subway stations in two cities are selected to test the PM2.5 concentrations in the station halls and platforms, and the PM2.5 concentrations in different spaces are compared. Based on the exposure characteristics of passengers in the subway stations, the PM2.5 inhalation of passengers in the station halls and platforms is calculated, respectively. The results show that when the outdoor PM2.5 concentration is higher than 35 μg/m3, the PM2.5 concentrations in the station halls and platforms are higher than the current standard value of 50 μg/m3. Combined with the outdoor PM2.5 concentration distribution, it can be inferred that the PM2.5 concentration in the subway stations exceeds the standard value for nearly 40% of the whole year. In most cases, the PM2.5 concentration in the subway stations is higher than that of outside, and the PM2.5 concentration in the platforms is about 1.54 times that of outside and about 1.32 times that in the station halls. The PM2.5 concentration in the subway stations during peak periods is slightly higher than that during off-peak periods, with a mean ratio of 1.3. The PM2.5 inhalation of passengers in a single trip in the subway stations is 2 to 20 μg, and the inhalation in the platforms accounts for 66%.