Cyclists’ exposure to air pollution and noise in Mexico City: Contribution of real-time traffic density indicators integrated into GIS.

Air pollution and road traffic noise are two important environmental nuisances that could be harmful to the health and well-being of urban populations. In Mexico City, as in many North American cities, there has been an upsurge in bicycle ridership. However, Mexico City is also well known for having high levels of noise and air pollution. The purpose of this study is threefold: 1) evaluate cyclists’ exposure to air pollution (nitrogen dioxide) and road traffic noise; 2) identify local factors that increase or reduce cyclists’ exposure, in paying particular attention to the type of road and bicycle path or lane used; and 3) evaluate the influence of real-time traffic density on cyclists’ exposure. A total of 19 bicycle trips made in central Mexico City neighbourhoods were analyzed, representing nearly 11 hours and 137 km. The results of the Bayesian models show that type of road and bicycle infrastructure taken by the cyclist, and proximity to a main artery all have significant impacts on exposure levels. Finally, the variables introduced to control for the traffic encountered by cyclists had a significant positive effect on noise exposure, and a positive but not significant effect on nitrogen dioxide exposure. [ABSTRACT FROM AUTHOR]