To investigate the characteristics of fine particulate matter (PM_2.5) pollution in Taichung, Taiwan, atmospheric concentrations of PM_2.5 and polycyclic aromatic hydrocarbons (PAHs) were measured weekly from 2016 to 2017 in Taichung and Saitama in the Tokyo metropolitan area of Japan. The following conclusions were drawn: (1) the annual mean concentration of PM_2.5 in Taichung was 27.7 µg/m³ (2016) and 31.1 µg/m³ (2017), which was twice that of Saitama and exceeded the long-term environmental standard of 15 µg/m³ in both years. (2) Two-year mean concentration of the 10 PAHs was 1.42 ng/m³, which was twice that in Saitama. (3) PM_2.5 and PAH concentrations were higher with the winter monsoon from China being most likely cause. (4) The correlation between PM_2.5 and the other pollutant concentrations revealed that the primary sources of PM_2.5, automobiles, thermal power plants, and factories were also significant. Based on the findings, reducing PM_2.5 concentration in Taichung requires not only reducing emissions from automobiles, but also implementing measures against power plants and factories. Additionally, it is effective in reducing PM_2.5 in China. We hope that the reduction in air pollutants in Taiwan and China will clean air in Taichung.