The impacts of long-term second-hand smoke exposure on the respiratory system of residents in Beijing

Objective To investigate the impacts of long-term second-hand smoke exposure on the respiratory system of residents in Beijing, including lung function, respiratory symptoms, chronic airway diseases and airway inflammation. Methods Eight hundred and thirty-five non-smoking residents over 35 years old of Xicheng District in Beijing were enrolled.Three hundred and eighty(45.5%) subjects had long term exposure to second-hand smoke.Questionnaires were used to investigate basic information chronic respiratory symptoms and respiratory diseases.Lung function including FEV1 and FEV6 were tested.EBC and blood were collected for the measurement of EBC pH, IL-6 and serum SPD.We compared these indices between the exposure group and control group, and also used regression analysis to assess the impacts of exposure duration on lung function, respiratory symptoms and diseases.Correlation between exposure duration and inflammation biomarkers was assessed using Spearman correlation test. Results Subjects in the exposure group were significantly younger and had a higher proportion of females.FEV1%pred was significantly lower in the exposure group and regression analysis indicated that FEV1 was lower with longer exposure duration.The exposure group had a higher prevalence of respiratory symptoms and diseases, but with no statistical difference.Logistic regression analysis showed that prevalence of chronic cough and chronic bronchitis increased with exposure duration, with OR of 1.243(95%CI: 1.058, 1.459) and 1.326 (95%CI: 1.031, 1.704) respectively.The exposure group had slightly lower EBC pH, whereas EBC IL-6 and serum SPD did not differ between two groups.In the exposure group, exposure duration was positively correlated with serum SPD. Conclusions Residents in Beijing exposed to second-hand smoke had lower FEV1%pred and higher airway inflammation biomarkers, and the impacts seemed to be more evident with longer exposure duration.The prevalence of chronic cough and chronic bronchitis also increased with exposure duration. Key words: Second-hand smoke; Pulmonary function; Exhaled breath condensate; Surfactant protein D; Chronic cough; Chronic bronchitis