Relation between indoor and outdoor exposure to fine particles near a busy arterial road.

Various studies on indoor and outdoor particulate matter in the urban environment in the vicinity of busy arterial roads in the centre of the subtropical city of Brisbane have indicated that the revised United States Environmental Protection Agency National Ambient Air Quality Standards (US EPA NAAQS) for Particulate matter PM2.5 could be exceeded not only outdoors but also indoors. The aim of this work was to investigate outdoor exposure to submicrometer particles and their relationship with indoor exposure in a hypothetical office building located in the vicinity of a busy arterial road. The outdoor exposure values and trends were measured in terms of particle number in the submicrometer size range and were then recalculated to represent mass concentration trends. The results of this study indicate that exposure to PM0.7 particles in ambient air close to a busy road often exceeds the levels of the annual and 24-hour US EPA NAAQS PM2.5 standards. It is likely that exposure to PM2.5 is even higher, and may significantly exceed these standards.