Background: Secondhand smoke triggers childhood asthma. Understanding sources of exposure, parental beliefs about exposure, and readiness to change that exposure are important for designing smoke exposure reduction interventions.
Methods: As part of screening for a clinical trial of a smoke exposure reduction intervention, 519 smoke-exposed children 3 to 12 years old with asthma provided urine specimens for cotinine testing, and their primary caregivers completed questionnaires.
Results: The urine cotinine to creatinine ratio (CCR) was lowest if neither the primary caregiver nor day-care provider smoked (mean CCR, 14.0; SD, 14.4), greater if either smoked (mean CCR, 22.2; SD, 21.3; and mean, CCR, 26.3; SD, 22.2, respectively), and greatest if both smoked (mean CCR, 39.6; SD, 27.5; p < 0.01). Parental perception of their child's exposure was weakly associated with the child's CCR (r(2) = 0.11, p < 0.001). Most parents (58.3%) reported that tobacco smoke exposure had small/no negative effect on their child's asthma. Substantial proportions of those for whom a specific exposure reduction action was relevant were classified as contemplating, preparing, or had recently taken action to reduce their child's exposure, including smoking cessation (61.3%), keeping the child out of smoke-exposed places (72.7%), and making the child's home (49.2%) and areas out of the home smoke free (66.9%).
Conclusions: Smoking by the primary caregiver and day-care provider are important sources of exposure for children with asthma. Parental assessment of their child's exposure is associated with biologically confirmed exposure but cannot be relied on to assess that exposure. Although the harm of smoke exposure was frequently underestimated, many parents appeared receptive to considering action to reduce their child's exposure.
Trial registration: (Clinicaltrials.gov). Identifier: NCT00217958.