Association between Traffic Air Pollution and Reduced Forced Vital Capacity: A Study Using Personal Monitors for Outdoor Workers

BACKGROUND The effects of outdoor air pollution on lung function in adults are still controversial. OBJECTIVE Evaluate the effects of exposure to different levels of traffic-generated PM2.5 on workers' lung functions in São Paulo, Brazil. METHODS To cover a wide range of exposures, 101 non-smoking workers from three occupations (taxi drivers, traffic controllers, and forest rangers) were selected for the study. After clinical evaluation, the participants were scheduled to attend four consecutive weekly visits in which they received a 24-hour personal PM2.5 sampler and had lung function tests measured on the following day. The association between the spirometric variables and the averaged PM2.5 levels was assessed using robust regression models adjusted for age, waist circumference, time at the job, daily work hours, diabetes or hypertension and former smoking habits. RESULTS Relative to workers in the lowest exposed group (all measures < 25 μg/m3), those with the highest level of exposure (all measures > 39.6 μg/m3) showed a reduction of predicted FVC (-12.2%; CI 95%: [-20.0% to -4.4%]), a marginal reduction of predicted FEV1 (-9.1%; CI 95%: [-19.1% to 0.9%]) and an increase of predicted FEF25-75%/FVC (14.9%; CI 95%: [2.9% to 26.8%]) without changes of FEV1/FVC. CONCLUSIONS Exposure to vehicular traffic air pollution is associated with a small but significant reduction of FVC without a reduction of FEV1/FVC.