Traffic Air Pollution and Respiratory Health: A Route Based Exposure-Symptom Study among Urban Taxi Drivers in Isfahan, Iran

Taxi drivers constitute one of the most at-risk subpopulations for road traffic air pollution within urban settings. In the polluted city of Isfahan, Central Iran, a cohort of 349 middle-aged male taxi drivers who were specifically exposed to road pollution was selected. Data collection involved assessing four respiratory symptoms (RSs)- coughing, dyspnea, wheezing, and chest tightness- using a 5-point Likert and a series of independent variables associated with the increase or abatement of air pollution along the routes that each driver took regularly during his working hours. A Generalized Additive Model (0.372 < R2 < 0.576) was applied to determine the prevalence of RSs in relation to a small subset of independent variables identified using a Varimax-rotated PCA analysis. According to the findings, increasing roadside greenery, as measured through a Sentinel-2 NDVI layer, decreases the prevalence of RSs. Conversely, an increase in the number of bus stations, the mean average travel time spent by the taxi drivers on the road between two destinations, and the mean annual concentration of PM2.5 along the routes (with an average of 23.99 ± 6.00 µg/m³) exhibited a positive association with the onset of RSs. This research underscored the susceptibility of taxi drivers to road traffic air pollution while highlighting the alleviating role of road greenery in influencing the respiratory health of Isfahan taxi drivers.