Estimation of occupational and nonoccupational nitrogen dioxide exposure for Korean taxi drivers using a...

Occupational and nonoccupational personal nitrogen dioxide (NO(2)) exposures were measured using passive samplers for 31 taxi drivers in Asan and Chunan, Korea. Exposures were also estimated using a microenvironmental time-weighted average model based on indoor, outdoor and inside the taxi area measurements. Mean NO(2) indoor and outdoor concentrations inside and outside the taxi drivers' houses were 24.7+/-10.7 and 23.3+/-8.3 ppb, respectively, with a mean indoor to outdoor NO(2) ratio of 1.1. Mean personal NO(2) exposure of taxi drivers was 30.3+/-9.7 ppb. Personal NO(2) exposures for drivers were more strongly correlated with interior vehicle NO(2) levels (r = 0.89) rather than indoor residential NO(2) levels (r = 0.74) or outdoor NO(2) levels (r = 0.71). The main source of NO(2) exposure for taxi drivers was considered to be occupational driving. Interestingly, the NO(2) exposures for drivers' using LPG-fueled vehicles (26.3+/-1.3 ppb) were significantly lower than those (38.1+/-1.3 ppb) using diesel-fueled vehicle (P <0.01). Since drivers spent most of their time inside their vehicle and indoors at home, a microenvironmental model was used to estimate the personal NO(2) exposure with indoor and outdoor NO(2) levels of the residence, and interior vehicle NO(2) levels (P <0.001). Some subpopulations, such as professional drivers, might be exposed to high NO(2) levels because they drive diesel-using vehicles outdoors in Korea.