Fig. 4

Percent of residents characterized as racial non-white minority (a) or impoverished (b) in various quartiles of pollutant exposure. Exposure continuums for each pollutant were divided into quartiles as described in Methods. Q1 represents the lowest exposed quartile and Q4 represents the highest. The total population as well as residents characterized as non-white or with incomes below the poverty line was determined for each census tract and then summed within each quartile. Racial minority and poverty were then expressed as a percent of the entire population within each quartile. The percentages of non-white and impoverished residents relative to the entire county population is shown for reference