Seasonal difference of indoor-outdoor relationship of PM2.5 in various microenvironments

摘要

Background/Aim: Exposure to fine particle (PM2.5) has been associated with increased morbidity and mortality in numerous epidemiologic studies. Since people spend most of their time indoors, outdoor concentrations are not sufficient to assess personal exposure to PM2.5. Indoor-outdoor relationship could provide valuable information of emission and exchange of air pollution. The purpose of this study was to determine I/O ratio of PM2.5 in various microenvironments in two seasons. Methods: Field technicians measured daily personal exposure to PM2.5 for 50 person-day both in summer and winter of 2017. PM2.5 concentrations were continuously measured using MicroPEM (RTI incorporated, USA). Microenvironments were classified into six categories including home, workplace/school, restaurant, other locations, private transportation, and public transportation. Outdoor concentrations were obtained from ambient monitoring stations in Seoul (AirKorea). I/O ratio of PM2.5 was calculated by microenvironmental concentration and outdoor concentration. Results: Average daily personal PM2.5 exposures were 20.8±30.7u.g/m3 in summer and 22.2±35.3ug/m3 in winter, while average outdoor concentrations were 22.2+12.3u.g/m3 in summer and 30.1±20.7u.g/m3 in winter. The highest PM2.5 I/O ratio in summer and winter were 2.5±3.5 and 3.8±8.3 in restaurant, respectively. The lowest PM2.5 I/O ratio in summer and winter were 0.8±0.7 in workplace/school and 0.6±0.5 in home, respectively. Other indoor locations, restaurant, and public transportation had PM2.5 I/O ratio higher than 1. Home, workplace/school, and private transportation had PM2.5 I/O ratio lower than 1. Conclusions: I/O ratio of PM2.5 was different by microenvironments. I/O ratio of PM2.5 in microenvironments was not changed by seasons. Indoor-outdoor relationship could indicate characteristics of the microenvironments.