On-road measurements of four pollutants (PM2.5, PM10, NO2, and O3) were continuously recorded by three U.S. EPA-certified FEM air pollution monitoring devices installed inside a vehicle traveling repeatedly on the same route in a near-road community. Spatio-temporal on-road air quality data were aggregated and compared to data collected at two fixed stations, one residence located 15 m from the frontage road adjacent to Interstate Highway I10, and another residential site 300 m from the frontage road. The first objective of this study is to assess the suitability of using the spatio-temporal on-road air monitoring data for representing community exposures to transportation-related air pollutants (TRAPs). While TRAP concentrations observed at a central state-operated site appear to be in good agreement with those observed in the near-road community, concentrations in the community may be better represented by spatio-temporal data generated by an on-road monitor. The second objective of evaluating the feasibility of using on-road air monitors instead of near-road monitors is supported by the facts that pollutants primarily emitted from sources other than traffic, such as PM10, display a different pattern than that of the other three pollutants. On-road monitors successfully detected PM10 concentrations near-road as well as in the community that are comparable to the regional background concentrations. PM2.5 and O3 detected by on-road monitors are also comparable to those detected near-road in the community. NO2 concentrations detected by the on-road monitors varied from the near-road monitors due to the complex interactions with ambient temperature, vehicle emissions, and atmospheric chemical reactions. It seems likely that community exposures to TRAPs can be represented by short-term spatio-temporal measurements using on-road monitors. On-road air pollution measurements provide a rapid assessment of the air quality in a community without installing multiple stationary sites.