Study of PM10 and PM2.5 indoor levels and chemical components in waiting room of bus terminal in Korea

摘要

IAQ(lndoor air quality in waiting room of bus terminal is easily influenced by a lot of inflow of external air because of frequent door opening and indoor source such as cooking process at dining room. Although people stay in a short time in bus terminal, they can be exposed by high particulate matter. In this study, we were focused on selectively large scale bus terminals that regulated by the related Korean laws. In addition, to investigate the impact of ambient air, we had monitored the outdoor air quality simultaneously. Measurement period for 7 targeted terminals was from September 2011 to July 2012 and average users per day were approximately 8,700 people. Indoor particulate matter levels were ranged 23.7～66.6 μg/m3 in the case of PM10, 12.8～56.2 μg/m3 in the case of PM2.5. This range is similar with that of outdoor. On the other hands, among all chemical components in indoor PM2.5, OC, NO3-, NH4+ were higher than those in ambient air. Indoor OC concentrations were showed higher than outdoor OC concentrations by bus and smoking emission that could be accumulated on indoor sites. Furthermore, cooking process is revealed as an additional indoor source of OC by using gases. Indoor NH3 and NOX are coming from using toilet and exhaust of vehicle. NH3 and NOX were oxidized to NH4+ and NO3- respectively. Consequently, these NH4+ and NO3-in indoor air reacted with each other and finally formed to NH4NO3. Also, Ca2+, Si, Al are recognized as markers for soil dust particles. Zn is revealed as a result of wearing process of automobile tires. Pb is explained by emissions of road dust. These high indoor anthropogenic components were suspected by inflow of outside air or re-suspensions by people's activity.