Purpose: To construct and validate a questionnaire aiming to measure children's exposure to environmental tobacco smoke (ETS) in the home.
Methods: The development of the instrument included epidemiological studies, qualitative interviews, pilot studies, and validation with biomarkers and is described in seven consecutive steps. Parents of preschool children, from different population-based samples in south-east Sweden, have participated in the studies.
Results: Content and face validity was tested by an expert panel and core elements for the purpose of the instrument identified. Reliability was shown with test-retest of the first version. The validation with biomarkers indicated that the sensitivity of the instrument was high enough to discriminate between children's ETS exposure levels. Cotinine/creatinine levels were related to parents' described smoking behaviors. Differences were shown between children from non-smoking homes, and all groups with smoking parents, independent of their smoking behavior (p < 0.01), as well as between parents smoking strictly outdoors and parents reporting indoor smoking (p < 0.001).
Conclusion: The results indicate that the presented instrument can be used to discriminate between different levels of ETS exposure and when children's level of tobacco smoke exposure is to be assessed.