Table 2.

Distributions of air pollutants and distance to roadway

Annual average of 2008	Median	IQR width	Range
PM2.5 (μg/m3)	9.6	1.6	1.0–15.6
Elemental carbon (μg/m3)	0.4	0.1	0.07–3.0
Ozone (ppb)	38.1	1.7	27.2–50.2
Annualized average from 2004 to 2008	Median	IQR width	Range
PM2.5 (μg/m3)	9.9	1.3	2.0–15.9
Elemental carbon (μg/m3)	0.4	0.1	0.1–1.4
Ozone (ppb)	38.4	1.9	24.4–50.7
	Median	IQR width	Range
Distance to major roadwaya (m)	211.4	363.0	0.02–1000

^aThe primary analysis excluded 292 participants (12.0%) who lived ≥1,000 m from a major roadway.

IQR indicates interquartile range.