Table 2. Concentration of the analytes found in hair samples from 48 non-smokers segregated by their self-declaration of living with at least one smoker or in a smoke-free home.

Group	Nicotine	Cotinine	NNN	NNK	NNAL
Exposed at home (N = 24)
Median (IQR) [pg/mg]	2,040 (1,200; 4,650)	49 (26; 106)	0.54 (0.29; 0.60)	1.3 (0.92; 2.7)	–
Mean (SE) [pg/mg]	3,320 (664)	74 (14)	0.54 (0.067)	2.1 (0.40)	–
N (quantifiable)	24	21	7	15	0
Non-exposed at home (N = 24)
Median (IQR) [pg/mg]	623 (221; 1,160)	26 (16; 43)	0.41 (−)	0.74 (0.31; 1.1)	–
Mean (SE) [pg/mg]	1,330 (527)	95 (55)	0.41 (0.027)	1. 1 (0.34)	–
N (quantifiable)	24	16	2	11	0
p (2-tailed) (Mann-Whitney)	0.001	0.030	–	0.018	–

Median (interquartile range (IQR)) and mean (standard error, SE) are given for each group.