There is conflicting reports on the respiratory health effects of indoor risk factor exposure. The aim of this study was to assess the association of indoor environmental factors to pulmonary function in an adult population in Zunyi City of Southwest China. Methods: Between July and Sep 2012, we conducted a cross-sectional survey of people aged ≥18 yr in 11 inner-city areas of Zunyi. Data on asthma and asthma-related symptoms and selected home environmental factors were assessed by

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... . Lung function measurements, including FVC, FEV1, FEV1/FVC and PEFR, were assessed and compared. Exposure to indoor and outdoor PM2.5 was monitored by measurement of PM2.5 emission relative concentration. Results: Cooking oil fumes, environmental tobacco smoke (ETS) and coal fuel use were associated with impaired lung function among adults in summer season (P<0.05). Subjects exposed coal fuel combustion, cooking oil fumes, pest in kitchen, mosquito repellent, fluffy blanket, pets, visible mold in bedroom and ETS (active and passive smoking) tended to exhibit greater decreases in FVC, FEV1 and PEFR values compared with their non-exposed counterparts (P<0.05). Median PM2.5 relative concentrations in kitchen, sleeping area and outdoor were 486.0cpm, 463.0cpm and 459.0cpm, respectively. PM2.5 relative concentration in indoor kitchen and sleeping area were significant higher than outdoor (P<0.001). Conclusion: A negative association between kitchen, sleeping area risk factors and ETS exposure and a reduction in lung function in summer was revealed in Zunyi.