People spend generally 90 percent of their time indoors, yet toxicity of household particles has not been thoroughly investigated before. The objective of this study is to examine particle size and components effects of household particles on human coronary artery endothelial cells (HCAEC). We used two micro-orifice uniform deposit impactors to collect 60 sets of indoor particulate matters (PM) from 30 houses in Taipei, Taiwan. Polycyclic aromatic hydrocarbons (PAHs) effects of household particles were determined by high-resolution gas chromatograph/high-resolution mass spectrometer, respectively. HCAEC were exposed to household particles extracts in three size ranges: PM0.1 (diameters less than 0.1 mu m), PM1.0-0.1 (diameters between 1.0 and 0.1 mu m), and PM10-1.0 (diameters between 10 and 1.0 gm) at 50 mu g mL(-1) for 4 h, and interleukin-6 (IL-6), endothelin-1 (ET-1), and nitric oxide (NO) concentrations in the medium were measured. We found that household PM1.0-0.1: was associated with increased IL-6 and ET-1 production and decreased NO synthesis. Naphthalene of PM1.0-0.1 was highly correlated with IL-6 and ET-1 production and NO reduction. We concluded that size and compositions of household particles were both important factors on inflammation and endothelial dysfunction in HCAEC. (C) 2013 Elsevier Ltd. All rights reserved.