BACKGROUNDThe effects of near-road pollution on lung function in China have not been well studied. We aimed to investigate the effects of long-term exposure to traffic-related air pollution on lung function, airway inflammation, and respiratory symptoms.

METHODSWe enrolled 1003 residents aged 57.96 ± 8.99 years living in the Shichahai Community in Beijing. Distances between home addresses and the nearest major roads were measured to calculate home-road distance. We used the distance categories 1, 2, and 3, representing <100 m, 100-200 m, and >200 m, respectively, as the dose indicator for traffic-related air pollution exposure. Lung function, exhaled breath condensate (EBC) pH, and interleukin 6 levels were measured. As a follow-up, 398 participants had a second lung function assessment about 3 years later, and lung function decline was also examined as an outcome. We used regression analysis to assess the impacts of home-road distance on lung function and respiratory symptoms. As the EBC biomarker data were not normally distributed, we performed correlation analysis between home-road distance categories and EBC biomarkers.

RESULTSParticipants living a shorter distance from major roads had lower percentage of predicted value of forced expiratory volume in 1 s (FEV1% -1.54, 95% confidence interval [CI]: -0.20 to -2.89). The odds ratio for chronic cough was 2.54 (95% CI: 1.57-4.10) for category 1 and 1.97 (95% CI: 1.16-3.37) for category 2, compared with category 3. EBC pH was positively correlated with road distance (rank correlation coefficient of Spearman [rs] = 0.176, P < 0.001).

CONCLUSIONSLong-term exposure to traffic-related air pollution in people who live near major roads in Beijing is associated with lower lung function, airway acidification, and a higher prevalence of chronic cough. EBC pH is a potential useful biomarker for evaluating air pollution exposure.