Investigation of pollution concentrations and pollution concentration gradients in communities adjacent to the Ports of Los Angeles and Long Beach using a mobile monitoring platform

The communities adjacent to the Ports of Los Angeles and Long Beach (the Harbor Communities) are surrounded by various pollution sources including refineries and freeways. The most important pollution source, however, is the thousands of heavy---duty diesel trucks (HDDT) that travel through this community on a daily basis. Thus, the Harbor Communities is an area of potentially high localized air pollution impacts with complex pollutant concentration gradients that cannot be readily identified by conventional monitoring approaches.;A mobile monitoring platform, a Toyota RAV4 electric vehicle outfitted with real-time monitoring instruments, was used to characterize pollution concentrations and gradients near busy roadways in the Harbor Communities with high temporal and spatial resolution. Measurements included several vehicle-related pollutants including black carbon and ultrafine particles (UFP).;Mobile monitoring measurements near busy roadways with HDDT showed the largest effects within 150 meters of a line source (e.g. freeways, busy arterials). Pollutant concentrations in these impact zones were often two to five times higher compared with areas greater than 150 meters from line sources (reference zones). However, these large impacts and the presence of concentration gradients were highly dependent on meteorology. The combination of the following explanatory variables, wind speed, fraction downwind, relative humidity, time of day, and season were able to explain 70% of the variability in the data, while data from a fixed site monitoring was found not to be a useful variable.;This was the first study that investigated real-time UFP size distributions from busy roads using a Fast Mobility Particle Sizer (FMPS). UFP size distribution and number concentration gradients were observed over a middle range of winds speeds (>0.5 m s-1 and < 2 m s-1). The FMPS was also used in the characterization of acceleration plumes from diesel and gasoline vehicles. A large peak in the accumulation mode for diesel vehicles was a key difference between UFP size distributions for gasoline and diesel vehicles.;This research demonstrated the utility of the mobile platform to monitor in an area such as the Harbor Communities, where various sources and changing meteorology required monitoring with high spatial and temporal resolution. These measurements are important to establish baseline concentrations in the Harbor Communities to assess efforts to reduce emissions from dirty diesel trucks and to provide better data for exposure assessment.