Table 3

Predictors of exposure in non-smokers living in non-smoking households

	Base	Univariate geometric mean (ng/ml)	Adjusted geometric mean (ng/ml)	p Value	Stepwise multiple r
Partner's cotinine (ng/ml)				< 0.0001	0.26
0	771	0.23	0.23
0.1	873	0.22	0.22
0.2	844	0.25	0.26
0.3	742	0.30	0.30
0.4	616	0.29	0.28
0.5–0.6	830	0.35	0.35
0.7–0.9	657	0.38	0.38
1–2.9	788	0.51	0.49
3+	111	0.74	0.74

Sex				< 0.0001	0.29
Men	3065	0.35	0.36
Women	3167	0.27	0.26

Season				< 0.0001	0.31
Spring & summer	3255	0.27	0.28
Autumn & winter	2977	0.35	0.34

Socioeconomic disadvantage score				< 0.0001	0.32
0	3154	0.28	0.29
1	2330	0.33	0.32
2	561	0.36	0.34
3	179	0.35	0.35
4	8	0.42	0.35

Age				< 0.0001	0.32
16–29	468	0.35	0.34
30–44	2099	0.32	0.32
45–60	1744	0.32	0.32
60+	1921	0.28	0.28

Region				< 0.0001	0.32
South & West	3325	0.29	0.30
Midlands	1346	0.30	0.30
North	1561	0.35	0.34

Year of survey				0.001	0.33
1994	2990	0.29	0.29
1996	3242	0.33	0.32

Respondent's smoking history				0.003
Never regular smoker	3888	0.30	0.30		0.33
Ex-smoker	2344	0.33	0.32

Marital status				0.04
Married	5863	0.30	0.30		0.33
Cohabiting	369	0.39	0.34