*3.2. Hourly PM Concentration and PM Reduction Rate*

In the case of hourly PM concentration, the PM<sup>10</sup> and PM2.5 concentrations were the highest during the morning rush hour, reaching 77.9 and 51.4 µg/m<sup>3</sup> , respectively (Figure 3a,b). The high PM concentration in the morning rush hour gradually decreased after noon, and the value in the evening rush hour was 30% lower than that in the morning rush hour. PM<sup>10</sup> and PM2.5 reduction rates were the highest (31.4% and 40.3%, respectively) during the evening rush hour, while those of the morning rush hour were the lowest (15.0% and 26.0%, respectively) (Figure 3c).

**Figure 3.** (**a**) Hourly PM<sup>10</sup> concentration (µg/m<sup>3</sup> ) at measuring points. (**b**) Hourly PM2.5 concentration (µg/m<sup>3</sup> ) at measuring points. (**c**) Hourly PM reduction rate (%). Different lowercase letters indicate significant difference between measuring points at a 5% level. Different uppercase letters indicate significant difference between hours at a 5% level. IC: industrial complex; UG: urban green area; RA: residential area.
