*2.3. Analysis Method*

We grouped the PM concentrations, meteorological factors, and air pollutants measured by season, i.e., spring (April and May), summer (June and August), and fall (September and October). To analyze the seasonal characteristics of PM reduction in UG, we performed the Pearson correlation analysis among these grouped data by using R v.3.0.2 (R Core Development Team 2019). Statistical analysis using the Tukey HSD procedure of R v.3.0.2 was also conducted on PM concentration and PM reduction rate. The least squares mean was used to test significant differences among measuring points and over month and hour at the 5% probability level.

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PM reduction rate ሺ%ሻ ൌ 100 ൈ

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