Comparison of Particle Number Concentrations Between Urban and Forests During the High Events of Particulate Matter in Seoul, Korea

We analyzed the effect of reducing particulate matter in a forest by comparing concentrations and particle number concentrations (PNC) between urban and forest areas with the use of aero-dynamic particle sizers. PM is observed at a forest and urban site during the high events of par-ticulate matter from April 22 to April 30, 2019. Comparing the PM concentrations measured, PM10 and PM2.5 were 61.6㎍/㎥and 36.9㎍/㎥, respectively in urban, while PM10 and PM2.5 were 53.9㎍/㎥, 31.8㎍/㎥, respectively, in forest. PNCs are classified by particle size and analyzed by dividing them into 0.5㎛. Most PNCs at both sites ranged in size of particles less than 0.5㎛ (99%). Comparing the distribution of PNC in the forest, the smaller the particle size, the higher the reduction rate. In low concentration events, the ratio of coarse mode particles (>0.5㎛) among forest PNC distributions was similar to that of urban, but the reduction rate of coarse mode particles was 20% in the high concentration event. For accumulation mode particles (< 0.5㎛), forests were 18% lower in low concentration events and 11.5% lower in high concentration events. These results indicate the forest can have the capacity to reduce the accumulation mode particles during high concentrations of PM.