Fine particulate matter (PM2.5) from different sources with different components have different health impact. In this research in Taiwan, composition and cytotoxicity of PM2.5 from long-range transport event (LRT), traffic activity, and outdoor cooking at night market were studied. The PM2.5 mass concentrations were 39.0 μg/m3 during LRT, 42.9 μg/m3 at traffic area, and 28.3 μg/m3 at the night market. Traffic area had highest concentrations of PCDD/Fs (46.9 fg I-TEQ/m3) when highest PAH concentrations of 3.57 BaPeq-ng/m3 were found at night market area. One quarter of PM2.5 mass at LRT and night market was constituted by water-soluble ion (26.02–28.93%). Road dust (represented by high concentration of Al and Ca) was the main contributor for metal element at traffic station whereas presence of natural salt (Na and Cl elements) was a marker of LRT and cooking activities. Cell viability reduced 9% after exposure to organic extracts of 0.316 μg of PM2.5 from LRT and night market samples. 150% elevation of ROS production was observed after exposure with organic compound of night market samples at the dose equivalent to 10.0 μg PM2.5. Organic extracts from night market induced positive genotoxicity in umu test (at a dose of 20.0 μg PM2.5).