Abstract: ObjectiveTo screen sensitive biologic markers and to explore the mechanism of the damage in pulmonary alveolus type Ⅱ epithelial cell(AT-Ⅱ)exposed to atmospheric mix pollutants.MethodsThe air particulate samples were collected with portable sampler for particulate matter of 2.5μm in diameter and glass fiber filter(47 mm).The particulates collected were mixed with normal saline and gavaged into trachea of the rats inhaling mixed air of sulfur dioxide,nitrogen dioxide,and carbon monoxide.The effects of air pollutants on pulmonary surfactant-associated protein A(SP-A)expression in pulmonary tissue,blood,bronchoveloar lavage fluid(BALF)of the rats were determined.ResultsThe SP-A mRNA expression level in pulmonary tissue 7 days after the exposure(1.86±1.299)was significantly decreased compared to that of rats with 1 or 30 days exposure(0.930±0.587,0.902±0.378)and that of the control group.The SP-A expression level in pulmonary tissue in 30 days exposure group was significantly decreased compared to 7 days exposure and the control group.The SP-A expression level in BALF of the rats with 30 days exposure was significantly decreased compared to that of with 1 or 7 days exposure and the control group.The SP-A expression level in blood in 30 days exposure group was significantly decreased compared to 1 day,7days exposure and the control group.ConclusionSP-A reflects the function of lung alveolus type Ⅱ cells and SP-A could be used as a specific indicator of lung function.