This study analyzes the chemical composition of PM2.5 with samples collected from the ambient environment, in-stacks and bus stops. The second focus of this study is air quality forecasting. The compositional analysis shows that the ambient PM2.5 consists of 22-26% sulfate, 20-24% organic carbon, 5-9% elemental carbon, 8~9% ammonium, 5-7% nitrate, and 5-7% metal element. The proportion of sulfate in Houli and Dali stations is the highest, followed by organic carbon. In 2018, three new PM2.5 automatic monitoring stations--in Beitun, Tungshih, and Heping--were set up to gain a better understanding of PM2.5 in the eastern mountainous region of the Taichung City jurisdiction. The monitoring data from April to September in 2018 shows that the PM2.5 pollution on the east side of the city is no higher than the west side. It is worth to note that in October, the eastern part of the city (Beitun, Tungshih, Heping) pollution is higher than the west. It is found that among the 19 stations, the Wenshan is the highest one for exceeding the standard level. Results of PM2.5 monitor of in-stack show that FPM is 0.89~1.19 mg/Nm3, CPM is 5.5~10.0 mg/Nm3 from Taichung Power Plant coal-fired boilers No. 1 and No. 7。 It shows that the PM2.5 pollution of the electric bus lower than that of the diesel one during the buses enter the station. The use of the electric bus can suppress the bus station PM2.5 from rising by about 4~9μg/m3. Therefore, we propose in the future to substitute electric buses for diesel ones to mitigate the traffic pollution. Due to migratory ozone from outside of the borders, results for June suffered higher levels of inaccuracy. The air quality forecast in Taichung subregions from March through October in 2018 down to an average accuracy of 56%.

Composition of PM2.5，Filterable Particulate Matter (FPM)，Condensable Particulate Matter (CPM)，PM2.5 Automatic Monitoring Stations，Air Quality Forecast