Citation:

BALDAUF, R. W., C. BAILEY, AND J. P. WEINSTEIN. ASSESSING EXPOSURES TO MOBILE SOURCE AIR TOXIC EMISSIONS FOR POPULATIONS LIVING NEAR ROADWAYS. Presented at CRC Mobile Source Air Toxics Workshop, Phoenix, AZ, November 30 - December 02, 2004.

Impact/Purpose:

The main research question guiding this task is "how do mobile source emissions impact public health and the environment." The main objectives of this task include:

(1) Identify spatial and temporal variability in pollutant concentrations near major mobile source emission locations such as urban roadways and non-road activities.

(2) Characterize real-world emissions from on- and non-road mobile sources for use in identifying hazardous components and developing and improving mobile source emissions and human exposure models.

(3) Develop mobile source emission profiles and markers for use in human exposure and air quality receptor models.

(4) Determine the impact of emerging technologies (fuels and engine systems) on emissions and exposures to toxic pollutants.

(5) Develop and improve analytical methods that measure emissions from mobile sources.

Description:

A growing number of epidemiological studies have identified an increase in occurrence of adverse health effects for populations living near major roads. However, the biological mechanism(s) leading to the adverse effects have not been identified. Limitations in exposure assessment have resulted in a need to evaluate and improve methods of predicting exposures in the near road environment. Questions remain on the spatial extent of the zone of influence of the road, and the factors affecting concentration variability including traffic volume, vehicle fleet mix, and fleet operating characteristics. Federal agencies have also been under increasing pressure to evaluate potential air quality and health impacts from roadway construction.

The Traffic-Related EXposure (T-REX) Study will provide data to characterize the temporal and spatial variability in pollutant concentrations in the near road environment. Air toxics measurements will be collected along 500 meter transects away from major roads with traffic volumes in excess of 100,000 vehicles per day. Air measurements include volatile organic compounds (benzene, toluene, ethylbenzene, zylenes), particulate matter (mass, number, elemental/organic carbon, semi-volatile organic carbon), and regulated gases (CO, CO2, NOx, and O3). Air quality measurements will be collected at fixed site locations, in a mobile monitoring vehicle, and at a fixed site trailer also equipped with meteorological monitoring devices (wind speed, wind direction, temperature, humidity and mixing height). In addition to ambient air quality measurements, monitors will be placed directly outside and inside buildings adjacent to the major roadways to determine contaminant infiltration. Air quality monitoring will emphasize continuous and near continuous measurement techniques. Tracer gas will also be released near the roadway to measure atmospheric dilution during the measurement period. Video recordings will be used to assess roadway activity during the collection of air quality measurements. Results of the study will provide detailed data to evaluate and improve exposure and air quality models supporting epidemiologic studies and assessments of transportation system impacts.

Although this work was reviewed by EPA and approved for publication, it may not necessarily reflect official Agency policy.

Record Details: