Assessing and predicting the exposures of polycyclic aromatic hydrocarbons (PAHs) and their carcinogenic potencies from vehicle engine exhausts to highway toll station workers

The objective of this study was set out to assess the exposure levels of both polycyclic aromatic hydrocarbons (PAHs) and their corresponding carcinogenic potencies for highway toll station workers associated with vehicle emissions. We collected 48, 35, and 33 personal PAH samples from booth attendants of the dayshift (08:00 AM−16:00 PM), nightshift (16:00 PM−00:00 AM), and late-nightshift (00:00 AM−08:00 AM), respectively. We found no significant difference in PAH homologue distributions among the workers’ exposure profiles of the three work shifts. Both total-PAH and total-BaPeq exposure levels for dayshift workers (=12,300 and 230 ng/m3, respectively) were not significantly different from that for nightshift workers (=11,500 and 203 ng/m3, respectively), but both were significantly higher than that for late-nightshift workers (=8280 and 151 ng/m3, respectively). We conducted multivariate linear regression analyses to relate booth attendants’ exposure levels to the involved vehicle flow rates and environmental factors. We found none of the three environmental factors (i.e., wind speed, humidity and air temperature) was significant. On the other hand, we found the vehicle flow rate was able to explain 76% and 62% variations of booth attendants’ total-PAH and total-BaPeq exposures, respectively. Considering measuring vehicle flow rate is much less labor consuming and costly than direct measuring PAHs, the above regression results can be regarded, at least, as a useful indirect approach for estimating the booth attendants’ exposure levels.