Dr. Garshick's work has included the study of diesel exhaust and fine particle exposure and the risk of human lung cancer in large epidemiologic studies. He has studied this both in a cohort of 54,000 US railroad workers occupationally exposed as a result of working with diesel locomotives, and in a national cohort of 54,000 US trucking company workers exposed on the roadways and in trucking terminals. As well as conducting epidemiologic studies, He works closely with an exposure assessment group. This provides information regarding the determinants of exposure in the populations under study, provides information that may permit the estimation of lung cancer risk.