Characteristics and Reduction Directions of Fine Particles by Regions in Korea

The high temporal resolution (1 hour) measurement data at five intensive air quality monitoring stations from January 1 to December 31 in 2020 were used (1) to find the characteristics of fine particles (PM 2.5 ) and (2) to estimate the sensitivity of the fine particles mass concentration to the variation of major ambient inorganic species, such as sulfate, total nitric acid (nitric acid + nitrate) and total ammonia (ammonium + ammonia). A gas-particle equilibrium model, ISORROPIA II, was used for the analysis. The acidities and aerosol water contents at the five stations were comparable to each other. The annual mean values for pH and the concentration of the aerosol water content were 3.7 and 15 μg/m 3 , respectively. At all stations, the fine particles mass concentrations were most sensitive to the variation of the concentrations of total nitric acid followed by those of sulfate and total ammonia. Ammonia reduction was effective for PM 2.5 reduction when ammonia was reduced by more than 60% of the 2020 level. Further research directions for effective air quality management are also suggested.