This study examined the environmental factors that affect indoor radon (Rn) and particulate matter (PM10) concentrations in underground public facilities such as subway stations and underground parking lots. Rn and PM10 concentrations from March 2014 to October 2015 were evaluated at 40 subway stations and 19 underground parking lots. Average underground concentrations of Rn and PM10 were 37.3 ± 17.1 Bq/m3 and 78.6 ± 15.1 μg/m3, respectively. There were significant difference in Rn concentration between sampling points, with the highest concentration 41.8 ± 18.1 Bq/m3 on subway platforms, while the highest concentration of PM10 was 83.7 ± 13.8 μg/m3 in transfer pathways. Rn concentration showed positive correlation with PM10 concentration (r = 0.380, p < 0.001). The highest Rn concentration occurred during fall season, followed by summer and spring. At 60-h exposure duration in underground subway stations and parking lots, the hazard quotient (HQ) of Rn exceeded 1 for children less than 1 year old and those between 8 and 10 years old.
Keywords: Indoor parking lot; PM10; Radon; Subway station; Underground environments.