PM2.5 is a particulate matter with an aerodynamic diameter of less than 2.5 µm. It is known that the particle enters the body through the respiratory system, causing asthma, respiratory disease, and cancer.
In this study, in order to understand the seasonal characteristics of PM2.5 in Yongin, Gyeonggi-do, the concentration and chemical composition of PM2.5, and gaseous precursors were measured at the Global Campus of Hankuk University of Foreign Studies. The study was conducted for about one month in spring/summer, fall, and winter to study the seasonal characteristics of PM2.5 in Yongin. In addition, this study analyzed the pollution source through CPF analysis and tried to identify the emission source of organic aerosol by using positive matrix factorization (PMF) analysis in spring/summer.
The average concentration of PM2.5 in winter was 27.45±18.91 µg/m3, and the concentration of PM2.5 exceeded the air quality standard in 30% of the study period. Compared to other seasons, the winter was a favorable environment to produce nitrate due to higher NO2 concentration and lower temperature. So, the ratio of NO3- was the highest at 37%. In addition, the yellow dust period was included in the measurement period, so the fraction of crustal on PM2.5 was higher than in other seasons. The PM2.5/PM10 ratio decreased during the yellow dust period. In spring/summer, due to the high temperature, NH4NO3 returned to gaseous HNO3, so the concentration of NO3- in the air was low, and the concentration of HNO3 was high. In addition, the concentration of biogenic volatile organic compounds (BVOC) increased, and the photochemical reaction became active, so the ratio of organic components in PM1 was higher than in other seasons. As a result of PMF analysis, 84% of the organic aerosol was secondary organic aerosol (SOA). And the cooking and combustion-related organic aerosol (CCOA) accounted for the significant portion of the total Organic Aerosol (OA). The CCOA is a state in which components emitted from biomass and coal combustion are oxidized. On November 21, Emergency reduction measures were issued in five provinces (Seoul, Incheon, Gyeonggi, Chungnam, and Chungbuk), as high concentrations of PM2.5 over 50 µg/m3 were expected.