Table 1.

Distribution of Ambient NO₂ Concentrations (ppb) at Reported Residence at Enrollment and First Follow-up (Age 6)

	n	GM	GSD	Median	IQR	Range
Enrollment (1980–1984)	1,137	10.96	1.41	11.00	6.00	4.18–27.30
First follow-up (1986–1990)	806	10.23	1.48	10.74	6.69	2.73–20.39

Definition of abbreviations: GM = geometric mean; GSD = geometric standard deviation; IQR = interquartile range; NO₂ = nitrogen dioxide.