Table 3 presents the distribution of selected participant characteristics overall and in relation to PM2.5 (1999–2000) concentrations. Most participants were between 50 and 69 years of age, were female, and had some postsecondary education. There was a tendency for higher PM2.5 concentrations to be observed in participants who were nonwhite, had a lower level of educational attainment, had a higher BMI, were nonmarried, and had a lower intake of vegetables, fruit, and fiber.