Health impact of inhalable and respirable dust exposure to outdoor workers in Bangkok and adjacent provinces

Exposure to air pollution can lead to a wide range of health effects. In Thailand, exposure to inhalable and respirable dust among outdoor workers has rarely been documented. Therefore, this study aimed to determine the health impact of inhalable and respirable dust exposure on 441 motorcycle taxi drivers in Bangkok and five adjacent provinces from January to March 2023. The study involved conducting face-to-face interviews with questionnaires. Lung function parameters of motorcycle taxi drivers were measured using spirometers. Additionally, respirable dust, PM10, and PM2.5 exposure were measured using personal air sampling, area sampling, and air quality monitoring stations. The results found that among six studied provinces, 90.2% of participants were males, 60.1% aged between 40- 59 years old, 44.2% were current smokers, 49.7% had been working as motorcycle taxi drivers for more than 10 years, 92.3% worked more than or equal to 8 hours a day, 70.5% wore surgical masks while driving. 10.9% of participants had the symptoms of chronic bronchitis, and 4.3% had the symptoms of acute bronchitis. The prevalence rate of lung function abnormality in participants was 34.9%. FVC (%predicted) of all motorcycle taxi drivers had a mean of 89.57 (SD ±17.82). FEV1 of (%predicted) had 96.60 (SD ±17.63). FEV1/FVC (%predicted) had 104.29 (SD ± 11.80). Pathum Thani had the highest average PM10 level at 224.9 µg/m3 as measured using personal air sampling, followed by Nakhon Pathom and Samut Sakhon at 169.6 µg/m3 and 165.8 µg/m3, respectively. Pathum Thani also had the highest average PM2.5 concentration at 410.9 µg/m3 as measured using personal air sampling, followed by Nonthaburi and Samut Sakhon at 206.2 µg/m3 and 149.0 µg/m3, respectively. These PM10 and PM2.5 levels were different from those measured at air quality monitoring stations or by area air sampling devices. In addition, Pathum Thani also had the highest incremental lifetime cancer risk due to exposure to PM10-bound total PAHs and PM2.5-bound total PAHs at 4.5×10−8 and 7.8×10−8, respectively. Bangkok had the second-highest average PM10-bound total PAHs at 1.9 × 108 and PM2.5-bound total PAHs at 5.8 × 109, followed by Samut Prakan, which had average PM10-bound total PAHs at 3.4 × 109 and PM2.5-bound total PAHs at 3.1 × 109, indicating that all levels were the acceptable risk level (1.0 × 106). The study found high average levels of PM10 and PM2.5 concentrations, as well as their bound total PAHs, in all the studied provinces. These findings raise concerns about human health risks, particularly for those who work outdoors. It is important to take further measures to monitor respirable dust concentration on the road in Bangkok and adjacent provinces in order to reduce respirable dust and PAHs present in vehicle exhaust. Additionally, it is necessary to establish a system for regular medical check-ups for motorcycle taxi drivers to monitor their health.