UCLA

This study characterizes the spatial and temporal distribution of air pollution in an urban street environment given traffic and meteorological conditions. A mobile air monitoring platform was used to measure ultrafine particle (UFP) counts on a 1-second basis along a 3 mile-long transect in Downtown Los Angeles in April-July 2008 for a total of 12 runs and roughly 7,500 observations. Significantly higher UFP concentrations were found in morning compared to afternoon measurements. Spatially speaking, mean UFP concentrations were higher at intersections. High emitting vehicles (HEV), typically old light duty vehicles or medium and heavy duty diesel trucks, were associated with higher spikes of pollution. Advanced statistical modeling is needed to understand how UFP plumes from accelerating vehicle queues disperse in the built environment while controlling for wind conditions. These findings inform smart growth and traffic management strategies, and ultimately, support the creation of a toolkit for transportation planners and policy decision makers to mitigate air pollution exposures in urban street environments and near transit-oriented development (TOD).