Table 2.

Distribution of pollutant exposures averaged over length of pregnancy, as measured within 10 km of mother's residential geocode.

pollutant	unit	N	mean	SD	interquartile range
CO	ppm	2,853,245	0.87	0.45	0.56 - 1.09
NO2	pphm	2,808,662	2.42	0.95	1.69 - 3.12
O3	pphm	3,303,834	2.35	0.65	1.89 - 2.74
SO2	ppb	1,167,449	2.10	1.08	1.25 - 2.84
PM10	μg/m3	1,778,579	31.4	11.2	22.6 - 38.7
PM2.5	μg/m3	1,402,622	16.7	5.5	12.0 - 21.0
PMcoarse	μg/m3	740,885	15.7	7.5	11.0 - 18.1