The effect of air pollution on drivers' safety performance.

Numerous studies have determined the adverse effects of air pollution on the health, welfare, and comfort of humans. More recently, the effects of air pollution on cognitive performance of humans are also focused. However, as a group in direct exposure to air pollution, drivers are rarely studied. The present study aims to evaluate the effect of air pollution on the performance of drivers. Their performance is evaluated by observing the number of recorded accidents. The effect of pollutant concentration (primarily PM2.5) on the number of accidents is investigated in a case study in Tehran. The temperature inversion phenomenon is used as an instrumental variable in a two-stage least squares method. The results indicate that temperature inversion had a significant positive correlation with the concentration of pollutants. Considering temperature inversion as an instrumental variable for these pollutants, it is observed that 1 μg/m3 increase in concentration of PM2.5, increased the number of accidents approximately by 4% in 1 day, for the range of parameters studied. No significant relationship was observed regarding the effect of NO2 and CO on accidents during the study period.