Subjects will participate in two exposure sessions. The air pollution exposure consists of a 2-hour car ride along the NJ Turnpike. Samples will be collected at 3 time points for each exposure session: pre-exposure, immediately post-exposure, and 24 hours post-exposure. Blood samples will be collected immediately before and after a 5-minute occlusion at each time point. The subject will also be asked to provide samples of exhaled breath and complete symptom and stress questionnaires at each time point.