Table 1.

Distribution of estimated cancer risks in continental U.S. metropolitan areas, per million.

	Mean	5th percentile	Interquartile range	95th percentile
All sources	631.9	129.3	272.4–696.5	1619.1
Background	23.0	23.0	23.0–23.0	23.0
Point (major) sources	7.9	0.1	0.6–6.2	26.3
Area sources	43.3	5.4	13.3–50.9	135.6
Mobile sources	557.6	94.8	223.9–605.7	1465.8
On-road mobile sources	178.5	39.3	90.9–227.9	422.8
Nonroad mobile sources	379.2	48.7	122.1–368.4	1097.8