The high lung cancer rate in Xuan Wei, China, is associated with smoky coal use in unvented homes. Smoky coal combustion emits higher levels of polycyclic aromatic hydrocarbons (PAH) than wood combustion. The study used DNA adducts as a biomarker for human exposure to PAH from combustion emissions. DNA adducts were determined by enzyme-linked immunosorbent assays (ELISA) in placentas and peripheral and cord white blood cells from Xuan Wei women burning smoky coal or wood and from Beijing women using natural gas. Color ELISA gave positive results in 58%, 47%, and 5% of the placentas from Xuan Wei women burning smoky coal without and with chimneys, and from Beijing women, respectively. Fluorescence ELISA indicated that 46%, 65%, 56%, and 25% of placentas were positive from Xuan Wei women without and with chimneys, Xuan Wei women burning wood, and Beijing controls, respectively. PAH-DNA adducts were detected in a higher percentage of placentas from Xuan Wei women exposed to smoky coal or wood emissions than those of the Beijing controls. The results suggest that DNA adducts can be used as a qualitative biomarker to assess human exposure to combustion emissions.