Table 2

Predictors of exposure to passive smoking in non-smoking adults

	Base	Univariate mean (ng/ml)	Adjusted mean (ng/ml)	p Value	Stepwise multiple r
Partner's cigarette consumption				0.0000	0.382
Non-smoker	6699	0.31	0.34
0.1–4	206	0.50	0.42
5–9	193	0.66	0.44
10–14	217	0.97	0.58
15–19	218	1.25	0.71
20–24	247	1.55	0.89
25–29	51	1.72	0.98
30+	71	1.99	1.11

Season				0.0000	0.401
Spring & summer	4098	0.33	0.33
Autumn & winter	3804	0.44	0.43

Sex				0.0000	0..416
Men	3753	0.42	0.43
Women	4149	0.34	0.33

Socioeconomic disadvantage score				0.0000	0.429
0	3772	0.32	0.34
1	3023	0.41	0.40
2	808	0.51	0.44
3	279	0.62	0.50
4	20	0.87	0.51

Partner's cotinine concentration (ng/ml)				0.0000	0.437
0–14	6542	0.31	0.34
15–99	241	0.55	0.49
100–199	267	0.77	0.55
200–299	381	1.04	0.58
300–399	291	1.23	0.65
400+	160	1.36	0.68

Region				0.0000	0.443
South & West	4182	0.35	0.35
Midlands	1713	0.38	0.38
North	2007	0.45	0.43

Year of survey				0.0000	0.445
1994	3739	0.35	0.35
1996	4163	0.40	0.39

Age (years)				0.0001	0.447
16–29	627	0.44	0.42
30–44	2666	0.38	0.38
45–60	2308	0.39	0.38
60+	2301	0.34	0.35

Respondent's smoking history				0.0001	0.449
Never regular smoker	4899	0.35	0.36
Ex-smoker	3003	0.41	0.40

Other smokers in household?				0.002	0.450
No	7576	0.37	0.37
Yes	326	0.58	0.45

Marital status				0.005	0.451
Married	7366	0.37	0.37
Cohabiting	536	0.52	0.43