Table 1

Reliability of questions assessing secondhand smoke exposure (SHSe) among adults

Reference population	Assessment	Exposure time	Exposure source	Values
SHSe status (yes/no)
Coultas et al, 198926: 149 participants aged 21–79 years asked 4–6 months apart asked if the source had smoked daily for ≥6 months	SHSe status	Pregnancy	Mother	κ=0.73***
		Childhood	Mother	κ=0.87***
			Father	κ=0.85***
Brownson et al, 199325: 37 cases and 73 controls asked 1.7–1.9 years apart. All non-smoking women participants of a larger lung cancer study in Missouri.	SHSe status	Childhood	Parents	93.6%^†, κ=0.82; SE=0.095
		Childhood	All household members	82.7%, κ=0.60; SE=0.090
		Adulthood	Spouse	83.6%, κ=0.67; SE=0.095
		Adulthood	All household members	80.0%, κ=0.59; SE=0.093
Living with a smoker (yes/no)
Pron et al, 198827: 117 controls (63 females and 54 males) in a case-control study of lung cancer in Toronto asked 6 months apart	Ever living in a house with a regular smoker	Lifetime	Any	κ=0.66; SE=0.08 (females: κ=0.61; SE=0.12) (males: κ=0.70; SE=0.11)
	Living with a regular smoker	Adulthood	Wife	N=53; κ=0.89; SE=0.064
			Husband	N=61; κ=0.89; SE=0.059
			Children	κ=0.24; SE=0.106
			Mother	κ=0.76; SE=0.103
			Father	κ=0.44; SE=0.077
			Sibling	κ=0.57; SE=0.117
			Other (relatives)	κ=0.16; SE=0.137
			Other (non-relatives)	κ=0.02; SE=0.093
Duration of exposure
Pron et al, 198827: 117 controls (62 females and 53 males) in a case-control study of lung cancer in Toronto asked 6 months apart	Years of SHSe Living with a regular smoker	Lifetime	Any	r=0.45; 95% CI 0.29 to 0.58 (females: r=0.46; 95% CI 0.24 to 0.64) (males: r=0.44; 95% CI 0.19 to 0.63)
			Spouse	N=58; r=0.25; 95% CI −0.01 to 0.48
			Wife	N=22; r=0.37; 95% CI −0.06 to 0.68
			Husband	N=36; r=0.20; 95% CI −0.14 to 0.50
			Parent	N=40; r=0.48 95% CI 0.20 to 0.69
			Mother	N=8; r=0.69; 95% CI −0.03 to 0.94
			Father	N=32; r=0.46 95% CI 0.13 to 0.70
			Other (relatives)	N=17; r=0.59; 95% CI 0.15 to 0.83
Coultas et al, 198926: 149 participants aged 21–79 years asked 4–6 months apart	Years of SHSe	Childhood	Mother	N=33; r=0.76
			Father	N=57; r=0.75
			Others	N=26; r=0.63
	Years of SHSe sharing the home with smoker(s)	Adulthood	Spouse	N=40; r=0.95
	Years of SHSe sharing the home with smoker(s)	Adulthood	Other household members	N=67; r=0.78
	Hours per day of SHSe	Childhood	Mother	N=31; r=0.18
			Father	N=55; r=0.54
			Others	N=20; r=0.51
		Adulthood	Spouse	N=39; r=0.25
		Adulthood	Other household members	N=58; r=0.54
Brownson et al, 199325:37 cases and 73 controls asked 1.7–1.9 years apart. All non-smoking women participants of a larger lung cancer study in Missouri.	Pack-years of SHSe	Childhood	All household members	60.9%, r=0.71
		Childhood	Parents	73.6%, r=0.81
		Adulthood	All household members	52.7%, r=0.77
		Adulthood	Spouse	60.0%, r=0.80
Intensity of exposure
Coultas et al, 198926: 149 participants aged 21–79 years asked 4–6 months apart. Amount of cigarettes per day respondents were exposed to by the source for ≥6 months.	Categorical cigarettes per day (<1, 1, >1 pack/day, or unknown)	Childhood	Mother	N=48; κ=0.22*
		Childhood	Father	N=79; κ=0.04*
		Adulthood	Spouse	N=64; κ=−0.04*
Pron et al, 198827: 117 controls (62 females and 53 males) in a case-control study of lung cancer in Toronto asked 6 months apart	No. of smokers living in the home			κ=0.55; SE=0.071 (females: κ=0.52; SE=0.1) (males: κ=0.57; SE=0.1)
Johansson et al, 200528: 15 smoking parents asked 2 weeks apart	No. of smokers living in the home			r=0.5

*p<0.05; **p<0.01; ***p<0.001.
↵† Percentage agreement.
κ, kappa; r, correlation coefficient.