A travel mode comparison of commuters' exposures to air pollutants in Barcelona

► We measured air pollution in travel microenvironments in a Southern European city. ► Travel modes explained much more of commuters' exposure variability than meteorology. ► Particulate pollutants in cars were 2-3 times higher than in active modes (walk, bike). ► Contrasts between modes were greatest for primary pollutants (CO then BC and UFP). ► Accounting for inhalation rate differences, pedestrians and cyclists pollution doses were comparable to car drivers.