Abstract: Objective To investigate the influence of indoor environment risk factors on pulmonary function in adults living in a city with acid rain contamination due to heavy coal-burning pollution in southwest China.Methods Totally 215 residents aged 18-63 years and without respiratory diseases were selected with random sampling from 11 urban communities in Zunyi city of Guizhou province and surveyed with a questionnaire interview and measurements of forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) between November 2011 and March 2012;indoor and outdoor concentration of airborne particulate matter less than 2.5 microns in aerodynamic diameter (PM_2.5) were detected simultaneously.Results The participants' FVC and FEV1 were inversely correlated with coal-burning smoke and cooking fume exposure and smoking.The participants living in a house with a kitchen separated from other rooms had higher FVC (3.5 L vs.3.0 L),FEV1 (3.4 L vs.2.8 L) and a lower FEV1/FVC ratio (93.4% vs.93.9%) compared to those without a separated kitchen;the participants living in a house without mouse and cockroach had higher FVC (3.5 L vs.3.4 L),FEV1 (3.4 L vs.3.2 L) and FEV1/FVC ratio (93.2%vs.92.1%) compared to those with the exposure to mouse and cockroach at home;compared to the smokers/ex-smokers,the non-smokers had higher FVC (3.6 L vs.3.4 L/3.2 L),FEV1 (3.5 L vs.3.2 L/3.0 L),and FEV1/FVC ratio (93.4%vs.93.2%/93.2%)(all P<0.05 except for FEV1/FVC ratio);the participants using a bedroom with only one other person had significantly higher FVC (3.5 L vs.2.7 L),FEV1(3.4 L vs.2.5 L),and FEV1/FVC ratio (93.4%vs.91.8%) compared to those with two or more other persons (P<0.05 for all).The results of airborne PM_2.5 measurement for kitchens and bedrooms and their outdoor ambient air of 21 participants' houses revealed the means of PM_2.5 counts per minute (CPM) of 517 (25 percent point-75 percent point:483.5-616.0)for the kitchens,484 (462.5-602.0) for the bedrooms,and 398 (378.5-411.5) for the outdoor ambient air samples.The FEV1/FVC ratio was inversely correlated with the CPM value of kitchen and bedroom PM_2.5.Conclusion Coal burning,smoking,pet allergen are indoor risk factors of pulmonary function reduction in urban adults during winter time.