Table 2

Reliability of questions assessing current secondhand smoke exposure (SHSe) among children

Reference population	Assessment	Exposure source	Values
Intensity of exposure
Zakarian et al, 200429: mothers with children aged ≤4 years recruited in a randomised controlled trial. The time between questions was immediate and repeated at baseline, 3-month and 6-month follow-up.	CPD: asked to report their smoking on typical days during the past 7 days	Mother	Weekday: r=0.97–0.98; weekend: r=0.95–0.99
Emerson et al, 199518: 91 families with an asthmatic child 6–17 years old asked 2 months apart	CPD smoked at home: diary (2-week period)	Parents	Workday: r=0.88; non-workday: r=0.60
Zakarian et al, 200429: mothers with children aged ≤4 years recruited in a randomised controlled trial. The time between questions was immediate and repeated at baseline, 3-month and 6-month follow-up.	CPD smoked at home: in the past 7 days	Mother	r=0.97–0.98
Emerson et al, 199518: 91 families with an asthmatic child 6–17 years old asked 2 months apart	Average CPD to which the child is exposed at home: diary (2-week period)	Not specified	r=0.84
Matt et al, 200023: 22 mothers of children <2.5 years old from an ethnically diverse sample of low-income, low-education families asked 2 months apart	Weekly no. of cigarettes smoked at home: in the past 7 days	Mother	r=0.91
	Weekly no. of cigarettes smoked at home: in the past 7 days	Father	r=0.87
Emerson et al, 199518: 91 families with an asthmatic child 6–17 years old asked 2 months apart	Weekly no. of cigarettes smoked at home	Parents	r=0.86
	No. of cigarettes to which the child is exposed at home: diary (2-week period)	Parents	Workday: r=0.82; non-workday: r=0.63
	Weekly no. of cigarettes to which the child is exposed at home	Parents	r=0.76
		All smokers	r=0.81
Matt et al, 200023: 22 mothers of children <2.5 years old from an ethnically diverse sample of low-income, low-education families asked 2 months apart	Weekly no. of cigarettes to which the child is exposed at home	All sources	r=0.88
		Mother	r=0.9
		Father	r=0.81
	Weekly no. of cigarettes to which the child is exposed at home and away from home	Parents and others	r=0.88
Hovell et al, 200230: 204 children with asthma 3–17 years old asked 5 days apart	No. of cigarettes smoked while the child was in the same room or car	All smokers	r=0.69***
Zakarian et al, 200429: mothers with children aged ≤4 years recruited in a randomised controlled trial. The time between questions was immediate and repeated at baseline, 3-month and 6-month follow-up.	No. of cigarettes to which the child was exposed in the car	Mother	r=0.90–0.93

*p<0.05; **p<0.01; ***p<0.001.
†Percentage agreement.
CPD, cigarettes per day; κ, kappa; r, correlation coefficient.