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 @article{cao_frey_2012, title={Modeling of human exposure to in-vehicle PM2.5 from environmental tobacco smoke}, volume={18}, DOI={10.1080/10807039.2012.672894}, number={3}, journal={Human and Ecological Risk Assessment}, author={Cao, Y. and Frey, H. C.}, year={2012}, pages={608–626} }
 @article{cao_frey_2011, title={Geographic differences in inter-individual variability of human exposure to fine particulate matter}, volume={45}, DOI={10.1016/j.atmosenv.2011.07.034}, number={32}, journal={Atmospheric Environment}, author={Cao, Y. and Frey, H. C.}, year={2011}, pages={5684–5691} }
 @article{liu_frey_cao_2010, title={Estimating in-vehicle concentration of and exposure to fine particulate matter near-roadway ambient air quality and variability in vehicle operation}, DOI={10.3141/2158-13}, number={2158}, journal={Transportation Research Record}, author={Liu, X. Z. and Frey, H. C. and Cao, Y.}, year={2010}, pages={105–112} }