Table 3.

Comparison of exposure to SHS categories among 6- to 19-year-olds, 2007–2010 NHANES (%).

Exposure to SHS	Maternal report of smoking during pregnancya,b		NNALc			Cotinine
	None	Any	Below LOD	Low	High	No	Low	High
NNAL
Below LOD	96	4	—	—	—	—	—	—
Low	90	10	—	—	—	—	—	—
High	67	33	—	—	—	—	—	—
Cotinine
No	97	3	78	20	2	—	—	—
Low	86	14	29	50	21	—	—	—
High	65	35	4	10	86	—	—	—
Self-report of household smokers
None	93	7	59	27	14	65	24	11
One	59	41	6	13	81	4	16	81
Two or more	55	45	2	9	89	4	7	89
Abbreviations: LOD, limit of detection; NHANES; National Health and Nutrition Examination Survey; NNAL, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol; SHS, secondhand smoke. aSerum cotinine categories were as follows: no (< 0.05 ng/mL), low (≥ 0.05 and < 0.268 ng/mL), and high (≥ 0.268 and < 14.6 ng/mL).bEstimates for report of maternal smoking during pregnancy are based on a different sample size due to missing information (n = 2,106). cUrinary NNAL categories were as follows: below LOD (< 0.001 ng/mL creatinine), low (≥ 0.001 and < 0.005 ng/mL creatinine), and high (≥ 0.005 and < 0.082 ng/mL creatinine).