Objectives: The validity of self-reports of traffic density on street of residence in cities has not been evaluated extensively yet.
Methods: This study compared traffic self-reports with exposure estimates based on traffic counts and emission measurements.
Results: Self-reports correlated well with traffic count data but less well with data from measurements of background emission.
Conclusions: As traffic counts primarily represent direct exposure to road traffic and emission concentrations primarily represent city background exposure to traffic-related pollutants, self-reports reflect direct traffic exposure more strongly than background exposure.