%0 Report
%A Julian D Marshall
%D 2002
%G eng
%T Exposure to Motor Vehicle Emissions: An Intake Fraction Approach, Master's Thesis
%1 7
%2 LBNL-51854
%X Motor vehicles are a significant source of population exposure to air pollution. Focusing on California's  South Coast Air Basin as a case study, I combine ambient monitoring station data with hourly time-activity  patterns to determine the population intake of motor vehicle emissions during 1996 -- 1999. Three  microenvironments are considered wherein the exposure to motor vehicle emissions is higher than in  ambient air: in and near vehicles, inside a building that is near a freeway, and inside a residence with an  attached garage. Total motor vehicle emissions are taken from the EMFAC model. The 15 million people  in the South Coast inhale 0.0048% of primary, nonreactive compounds emitted into the basin by motor  vehicles. Intake of motor vehicle emissions is 46% higher than the average ambient concentration times the  average breathing rate, because of microenvironments and because of temporal and spatial correlation  among breathing rates, concentrations, and population densities. Intake fraction (iF) summarizes the emissions-to-intake relationship as the ratio of population intake to total  emissions. iF is a population level exposure metric that incorporates spatial, temporal, and interindividual  variability in exposures. iFs can facilitate the calculation of population exposures by distilling complex  emissions-transport-receptor relationships. I demonstrate this point by predicting the population intake of  various primary gaseous emissions from motor vehicles, based on the intake fraction for benzene and  carbon monoxide.