Table 2.

Distributions of Exposure Estimates

Exposure	n	Median	IQR	Range
Distance to major roadway, m
At birth	612	1,106	1,924	3–12,724
At mid-childhood visit	614	1,299	2,330	8–12,938
PM2.5, μg/m3
First year of life	580	12.09	2.63	8.26–17.62
Lifetime	599	10.71	1.99	6.74–16.35
Past 365 d	611	9.40	2.57	4.08–16.23
BC, μg/m3
First year of life	586	0.68	0.25	0.20–1.38
Lifetime	556	0.53	0.21	0.17–1.19
Past 365 d	571	0.46	0.20	0.13–1.06

Definition of abbreviations: BC = black carbon; IQR = interquartile range; PM_2.5 = particulate matter with a diameter smaller than 2.5 μm.

Data from 614 children participating in Project Viva.