Characterization of chemical components and cytotoxicity effects of indoor and outdoor fine particulate matter (PM2.5) in Xi'an, China.

The chemical and cytotoxicity properties of fine particulate matter (PM2.5) at indoor and outdoor environment were characterized in Xi'an, China. The mass concentrations of PM2.5 in urban areas (93.29~96.13 μg m-3 for indoor and 124.37~154.52 μg m-3 for outdoor) were higher than suburban (68.40 μg m-3 for indoor and 96.18 μg m-3 for outdoor). The PM2.5 concentrations from outdoor environment due to fossil fuel combustion were higher than indoor environment. An indoor environment without central heating demonstrated higher organic carbon-to-elemental carbon (OC / EC) ratios and n-alkanes values that potentially attributed to residential coal combustion activities. The cell viability of human epithelial lung cells showed dose-dependent decrease, while nitric oxide (NO) and oxidative potential showed dose-dependent increase under exposure to PM2.5. The variations of bioreactivities could be possibly related to different chemical components from different sources. Moderate (0.4 < R < 0.6) to strong (R > 0.6) correlations were observed between bioreactivities and elemental carbon (EC)/secondary aerosols (NO3-, SO42-, and NH4+)/heavy metals (Ni, Cu, and Pb). The findings suggest PM2.5 is associated with particle induced oxidative potential, which are further responsible for respiratory diseases under chronic exposure.