4. Discussion
The purpose of this study was to compare tobacco smoke exposure [TSE] among children who live in smoking families versus those who do not, as well as among children who live in smoking households with varying smoking locations. We found that about a third of children of non-smoking parents were measurably exposed to tobacco smoke, and roughly double that proportion were exposed in smoking families. Among smoking families, a majority of children in all locations were exposed to detectable TSE, even when parents limited smoking to a porch, a designated room in the house, a window, or the yard. The location of smoking in and around the home was not significantly associated with child exposure, implying that there is no smoking location which reliably protects children from TSE in many Israeli homes.The finding that about a third of children in non-smoking families were exposed raises questions about how this exposure occurred. Most of the families (85%) in this small sample reported that smoking was not allowed anywhere in or around the home, including indoors, on porches, in yards, or in gardens. Exposure may have taken place via numerous potential routes, such as tobacco smoke incursion from neighboring apartments [The greater proportion of children exposed to tobacco smoke in smoking families relative to non-smoking families indicates that parental smoking has a key role in child exposure, regardless of where it occurs, and that parental cessation should be encouraged. The exposure is likely caused by a combination of factors, including second- and third-hand exposure. Parents may smoke in close proximity to their children [see Most families in our study (99/141 = 70.2%) allowed smoking on the porch. We found that 61.8% of children from smoking families where home smoking was restricted to the balcony had measurable TSE. Similarly, Bahceciler et al. in Turkey found that 67.6% of children whose parents restricted smoking to outdoor porches were exposed [Indeed, many porches in Israel are entirely or partially within the perimeter of the apartment itself (see Smoke drift plays an important role in contamination. Sureda et al. conducted a systematic review of SHS in open and semi-open settings and concluded that high SHS levels were present in smoke-free indoor settings that were adjacent to open or semi-open smoking areas [Living conditions in Israel may have affected the exposure of children from both smoking and nonsmoking families. Israel has a very high population density, and most people (74%) live in multi-unit apartment buildings [Because tobacco smoke incursion from outside the home affects many Israelis, even parental cessation will not completely protect children. An Israeli cross-sectional study showed that 44% of Israelis have experienced tobacco smoke incursion into their own homes, with those of low socio-economic status being disproportionally affected [This study has some limitations. First, the study of smoking families, though it included objective TSE assessment through biomarkers in 141 children, had limited power to detect small differences in exposure. The study of nonsmoking families was small and did not allow multivariable analyses. Second, it is possible that social desirability bias affected the parents’ reporting regarding smoking in the home, resulting in misclassification of the location of smoking even though the interviewers were present in the home at the time of the interview. Third, we did not have information on the smoking habits of visitors (frequent or not) to the home or on whether the children regularly spent time outside of the home with people who smoked or in places where smoking was common, including in cars. We did not have information on the possible confounders of tobacco smoke incursion from nearby apartments, crowding in the home, or small dwelling size. Neither sample was based on a random sample of the population. Finally, it is likely that the effect of smoking in the vicinity of the home on child TSE differs in different areas due to different architectural customs and local climates.