Impacts of air pollution on respiratory symptoms and pulmonary functions among public drivers in Chiang Mai

Objectives To explore differences in pulmonary functions, respiratory symptoms and related factors among public commercial drivers between periods of high and low air pollution. Methods This cross-sectional analytical study comparing the same individuals during periods of high and low air pollution was conducted using spirometry and a self-administered questionnaire which included respiratory symptoms, personal factors, work-related factors and personal personal health data. Air pollution data were collected from reports of the Pollution Control Department. The statistic tests used were the Wilcoxon signed-rank test and McNemar’s test. Results Among the 49 subjects included in both periods (with one outlier removed), differences were found in forced expiratory volume (FEV1) and forced vital capacity (FVC) between periods of high and low air pollution (p = 0.030 and 0.042, respectively). Closing windows, wearing more respiratory protection, having no extra work and reducing exposure to second-hand smoke showed differences in FEV1 between the high and low air pollution periods (p = 0.013, 0.003, 0.049, and 0.034, respectively). Among the 22 subjects who had abnormal pulmonary function during the high air pollution period, the respiratory function of 10 individuals improved during the period of low air pollution. Respiratory symptoms which differed between the periods of high and low air pollution were night coughing and morning phlegm (p = 0.034 and 0.021, respectively). These results might have been affected by the COVID-19 situation which resulted in reduced working hours and hence less exposure time. Conclusions Air pollution is associated with lung function and respiratory symptoms. Abnormal pulmonary function which occurs during periods of high air pollution can improve as the level of air pollution declines. Policies and education campaigns, e.g., closing windows while driving, wearing respiratory protection and avoiding second-hand smoke, can help reduce the impact of air pollution. Chiang Mai Medical Journal 2021;60(1):27-40. doi 10.12982/CMUMEDJ.2021.03