Abstract
Pollutant emissions at toll stations are expected to be different than at a normal free flowing traffic environment because of stop and go movement of the vehicles at toll stations. This study therefore aimed at investigating the personal exposure of workers at a toll station on a busy national highway. Results showed that toll workers inside the toll collection cabins were exposed to higher DPM (Diesel particulate matter) concentrations (79.6 +/- 27.24 mu g m(-3)) than kerbside workers (73.52 +/- 40.9 mu g m(-3)). The in-cabin and kerbside PM2.5 (particles with aerodynamic diameter <= 2.5 mu m) concentrations were 86.1 +/- 45.4 mu g m(-3) and 79.20 +/- 48 mu g m(-3), respectively. For PM10 (particles with aerodynamic diameter < 10 mu m) it was 169.56 +/- 58.83 mu g m(-3) in-cabin and 156.41 +/- 80.72 mu g m(-3) at the kerbside. DPM and PM (PM2.5 and PM10) evening concentrations were similar to 2 times higher than the morning concentrations, primarily due to increased traffic and lesser atmospheric dispersion of pollutants. Stepwise regression models showed that temperature, relative humidity and wind speed significantly influenced the DPM and PM concentration. The General Linear Model analysis showed that the predictors could explain 53% (DPM concentrations), 71% (PM2.5 concentration) and 55% (PM10 concentration) variability. Worker's respiratory deposition dose of pollutants was higher (similar to 2-3 times) inside the toll cabin than at kerbside; higher in the evening (similar to 2 times) than morning and higher (similar to 1.5 times) on weekdays than on weekends. The present study demonstrates the need to focus on different policies to control the pollution concentration in workplaces, especially at places having proximity to traffic.
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