Relationship between PM1.0 and PM2.5 in urban and background areas of Republic of Korea

Abstract

Seasonal intensive measurements of atmospheric particulate matter with aerodynamic diameters less than or equal to a nominal 1.0 mu m (PM1.0) and 2.5 mu m (PM2.5) were conducted at an urban (Seoul, SL) and a background site (Baengnyeong, BN, an island about 200 km from SL) in Korea to fully understand the characteristics of PM1.0 within PM2.5, as well as the differences in PM characteristics between urban and background sites. A singlechannel particle sampler with PM1.0 and PM2.5 cyclones was used to collect the samples simultaneously. Eight ions (Cl-, NO3-, SO42-, Na+, NH4+, K+, Ca2+, and Mg2+), carbonaceous components (organic carbon (OC) and elemental carbon (EC)), and ten elements (As, Cd, Cu, Zn, Pb, Cr, Mn, Fe, Ni, and Al) were analyzed. The ratio of PM1.0 to PM2.5 mass concentration was approximately 80%, and the coefficients of determination (r(2)) between PM1.0 and PM2.5 was higher than 0.95 at both sites. PM1.0 was primarily responsible for the chemical composition of PM2.5. At both sites, OC was the most prevalent component of PM1.0 and PM2.5, followed by NO3-, SO42-, NH4+, and EC. According to source apportionment of the PMF model, PM1.0 and PM2.5 were explained from nine and eight factors at both SL and BN, respectively. At both sites, the significantly larger proportion of the factors of PM1.0 and PM2.5 were secondary inorganic aerosol and the contributions of sources for PM2.5 in SL and BN were comparable to those of PM1.0. This study confirmed that (1) PM1.0 and PM2.5 showed similar characteristics at both SL and BN and (2) PM1.0 contributed significantly to the chemical composition and sources of PM2.5 both in SL and BN, implying that PM1.0-2.5 had a minor impact on PM2.5 in these two sites. Thus, though further studies are needed, it is likely that the current air quality management direction for PM2.5 is also effective in managing PM1.0 in Korea.