Table 1.

Relative incidence of EJ Census Tracts in Allegheny County, PA increase as a function of pollutant exposure

	Quartile 1	Quartile 2	Quartile 3	Quartile 4
Black Carbon	1	2.0 (1.2–3.6)	2.4 (1.4–4.1)	3.6 (2.2–5.9)
NO2	1	5.7 (2.0–15.9)	8.7 (3.2–23.5)	18.5 (7.1–48.7)

Data represent the fold-increases in the number of tracts meeting the criteria for EJ designation among the approximate 100 tracts represented in each quartile of increasing BC or NO₂ exposure relative to the occurrence of EJ tracts in the lowest exposed quartile. Parentheses represent the 95% confidence interval for the determination