INT J TUBERC LUNG DIS 18(4):499–504 Q 2014 The Union http://dx.doi.org/10.5588/ijtld.13.0648
Home environmental tobacco smoke exposure in Canadian children A. L. Slogrove,*† J. A. Bettinger‡ *School of Population & Public Health, Faculty of Medicine, University of British Columbia, Vancouver, Canada; † Department of Paediatrics and Child Health, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa; ‡Vaccine Evaluation Center, Department of Pediatrics, BC Children’s Hospital, University of British Columbia, Vancouver, Canada SUMMARY BACKGROUND:
Children living with a smoker experience increased environmental tobacco smoke (ETS) exposure, even when the smoker refrains from smoking inside the house, compared to children not living with a smoker. Given the risks of ETS in children, it was hypothesized that households with children are less likely than those without children to experience home ETS exposure. D E S I G N : Cross-sectional analysis of the Canadian Community Health Survey 2009–2010 for the association between children aged ,12 years in the household and home ETS exposure, using logistic regression and considering household education and income as confounders or effect modifiers. A subgroup analysis was conducted comparing younger child households (at least
one child aged ,6 years) to older child households (only children aged 6–11 years). R E S U LT S : Of 66 631 households included, home ETS exposure occurred in 25% of households without children and 22% of households with children. Households with children were less likely than those without children to experience ETS exposure (OR 0.83, 95%CI 0.80–0.87). Effect modification by education and income was observed. No difference was observed in ETS exposure between older child and younger child households (OR 0.98, 95%CI 0.91–1.05). C O N C L U S I O N : Households with children are marginally less likely than households without children to experience home ETS exposure. K E Y W O R D S : environmental tobacco smoke; tobacco; secondhand smoke
CANADA has seen consistent reductions in smoking and environmental tobacco smoke (ETS) exposure, with only 5.5% of adult Canadians reporting home ETS exposure.1,2 This exposure varies according to age, with 12.6% of Canadians aged 12–19 years who are exposed compared to 3–6% of those aged 20 years.2 There are no published Canadian estimates of home ETS exposure in children aged ,12 years. In addition to the long-term consequences of ETS experienced by the general population (e.g., lung cancer and heart disease), children exposed to ETS experience higher rates of sudden infant death syndrome, respiratory tract and ear infections, and severe asthma during childhood.3 In the United States, ETS exposure in children aged ,12 years is associated with low socio-economic status, lower levels of parental education, and homes headed by someone other than the parents of the child.4 After controlling for family income and the number of adults in the home, White children in the United
States were more likely to live with a smoker than Hispanic, Black, or Asian/Pacific Islander children.5 The above estimates of ETS exposure were based solely on exposures associated with smokers who smoked inside the house.2,4 In the case of infants and young children, ETS exposure estimates that exclude smokers who live but do not smoke inside the house underestimate the number of children at risk of the negative effects of ETS. Infants are particularly vulnerable to third-hand smoke trapped in hair, skin, home furnishings, and dust released slowly into the atmosphere over time.6,7 Infants living in homes with smoking parents who diligently took precautions to avoid exposing their infants to ETS by only smoking outdoors still experienced levels of exposure five to seven times higher than infants not living with a smoker.6 Given the well-publicized risks of ETS, one would expect that adults in households with young children would be less likely to smoke than adults living in households with older children or no children.
Correspondence to: A L Slogrove, Vaccine Evaluation Center, A5-173 950 West 28th Ave, Vancouver V5Z 4H4, BC, Canada. Tel: (þ1) 604 875 2422. e-mail: [email protected] Article submitted 2 September 2013. Final version accepted 17 December 2013.
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Contrary to this expectation, it was observed in the United States that more adults living with children smoke compared to adults who do not live with children (23% vs. 21%), and 34% of children live with an adult smoker compared to 7% of nonsmoking adults living with an adult smoker.5 These observations suggest a lack of awareness among adults of the risks of ETS exposure to children specifically. This study examined the association between the presence of children in the home and home ETS exposure with the hypothesis that households with children would be less likely than households without children to experience home ETS exposure.
STUDY POPULATION AND METHODS Study design This was a cross-sectional study using the Public Use Microdata File (PUMF) for the 2009–2010 Canadian Community Health Survey (CCHS), an annual survey performed by Statistics Canada that collects nationally representative health-related data. The Canadian population aged 12 years was randomly sampled and participation was voluntary. The sample was limited to a single respondent per household. A response rate of 72.3% was achieved. Approximately 2% of the population was not represented by the 2009–2010 CCHS.8 All CCHS respondents provide informed consent for participation and the PUMF made available by Statistics Canada was accessed in accordance with the University of British Columbia Policy #89 (clause 7.10). Study sample The 2009–2010 CCHS included 124 188 respondents. Excluded from the sample were respondents living alone (27.1%), those with an unknown/unstated living arrangement (4.5%), unstated smoking status (0.5%), or non-smoking respondents with unknown/unstated home ETS exposure (0.5%). The non-response rates in the remaining sample for total household income and household education were respectively 17.3% and 7.6%. Only respondents with valid responses for household education and income were included in the final analytic sample of 66 631 respondents, each representing a single household. This provided an adequate sample size at alpha 5% and beta 10% to detect a 2% difference in the proportion of households with home ETS exposure between younger child households (21%), older child households (23%), and households without children (25%). Variable definitions The primary outcome variable was binary: 1) home ETS exposure – at least one smoker living in the household, irrespective of whether the smoker was reported to smoke inside the house, or 2) no home
ETS exposure – no smokers living in the household. The primary explanatory variable was the presence of children in the household: 1) households without children, i.e., no person aged ,12 years, and 2) households with children, i.e., at least one person aged ,12 years. Additional socio-economic variables evaluated included racial origin of the respondent (as a proxy for the household), either White or visible minority as categorized by the CCHS, highest level of household education, and household income. Analysis plan Descriptive statistics were calculated as frequencies for each variable and associations were determined by logistic regression with the degree of precision around point estimates represented by 95% confidence intervals (CIs). The primary analysis evaluated the association between home ETS exposure and households with children compared to households without children, described with an unadjusted odds ratio (OR). Third level variables for consideration as either confounders or effect modifiers were determined conceptually and based on previous evidence, and included racial origin, highest level of household education, and household income as defined by the CCHS. Differences in home ETS exposure across Canadian provinces were evaluated. To differentiate between confounding and effect modification, stratified analyses were conducted. The concept of effect modification as proposed by van der Weele was utilized, distinguishing effect modification from interaction (effect modification describes the association between the primary exposure and outcome when the primary exposure is conditioned on a secondary exposure; interaction describes the association jointly between the primary and secondary exposure on the outcome).9 Multivariable logistic regression was used to adjust for confounding according to the absence of effect modification.10 The Cochran-Armitage trend test was performed for variables that appeared to have a dose-response relationship with the outcome (household education and income). Due to the high proportion of respondents with unstated household education and income excluded from the final primary analytic sample, a sensitivity analysis was conducted for the unadjusted OR of home ETS exposure. The sensitivity analysis sample included all respondents with unstated household education and income (n ¼ 84 336) compared to the final primary analytic sample (n ¼ 66 631). A subgroup analysis of only those households with children aged ,12 years evaluated whether the age of children in the household was differentially associated with home ETS exposure. Households with children were categorized for comparison into two subgroups: 1) young child households, i.e., at least one child aged ,6 years, or 2) older child households, i.e., all children
Home tobacco smoke exposure in children
aged 6 years. Similar to the primary analysis plan above, the bivariable association for this subgroup analysis was described using an unadjusted OR; a stratified analysis was conducted to differentiate between confounding and effect modification by household education and income. In the absence of effect modification, a multivariable logistic regression model was determined adjusting for racial origin, household education, and household income; a sensitivity analysis including respondents with unstated household education and income was conducted. Probability weights calculated from the masterweights supplied by Statistics Canada were applied to each respondent for calculation of all proportions and regression analyses to maintain weighting of respondents according to the CCHS sampling strategy while calculating appropriate estimates of precision according to the sample size. Statistical analysis was conducted using SAS, version 9.3 (Statistical Analysis Software Institute, Cary, NC, USA).
RESULTS Description of study sample Of the 66 631 Canadian households included in this study, 81.5% were represented by a respondent of White racial origin, 80.8% had an occupant with post-secondary education graduation, and the majority (53.8%) had an annual household income of ,80 000 Canadian dollars (Table 1). This is compared to the general Canadian population as represented by the complete CCHS sample, including 77.4% of households represented by a respondent of White racial origin, 70.2% with post-secondary
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graduation, and 66.8% of households with an income of ,80 000 Canadian dollars. Almost a quarter (24.0%) of the households in the study sample experienced home ETS exposure, 26.5% had at least one child aged ,12 years, and 14.7% at least one child aged ,6 years. More households without children than households with children experienced home ETS exposure (25% vs. 21.6%). Provincial variation in home ETS exposure ranged from 18.2% to 39.5%. Primary comparison Households with children were 17% less likely to experience home ETS exposure than households without children (OR 0.83, 95%CI 0.80–0.87) (Table 2, column 2). Stratification by household education and income modified this association (Table 3, columns 2 & 3). The highest education and income strata showed some protective effects for households with children (OR 0.78, 95%CI 0.74–0.81 and OR 0.70, 95%CI 0.65–0.75, respectively). However, the lowest education and lowest income strata showed a 2.56 (95%CI 2.12–3.10) and a 1.13 (95%CI 0.97– 1.32) times greater probability, respectively, of home ETS exposure for households with children. Due to the presence of effect modification by household education and income, multivariable logistic regression adjusting for these variables was not performed. Increasing household education and income were both significantly associated (P , 0.0001) with no home ETS exposure in the full study sample and in both exposure groups (households with and without children), showing a dose-response relationship. Adjustment for province of residence (model not
Table 1 Distribution of characteristics comparing ETS unexposed homes and ETS-exposed homes in the CCHS, 2009–2010 (weighted percentages) Total study sample (n ¼ 66 631) n
%
ETS-unexposed homes (n ¼ 50 452) %
Children in the household Households without children (all 12 years) Older child households (all 6 – 11 years) Younger child households (at least 1 – ,6 years)
48 797 7173 10 661
73.4 11.8 14.7
72.6 12.2 15.2
76.1 10.8 13.2
Racial origin (respondent)* White Visible minority
58 078 8553
81.5 18.5
80.7 19.3
84.2 15.8
Household education Less than secondary Secondary graduation Some post-secondary Post-secondary graduation
4558 7146 3309 51 618
4.8 9.4 5.1 80.8
4.0 7.9 4.5 83.6
7.3 14.1 7.0 71.7
Household income, Canadian dollars ,20 000 20 000–39 999 40 000–59 999 60 000–79 999 80 000
3242 11 581 12 462 11 417 27 929
5.0 14.8 16.7 17.3 46.2
4.1 13.5 16.0 16.9 49.5
7.6 19.1 19.1 18.5 35.7
*According to categories as provided by the CCHS. ETS ¼ environmental tobacco smoke; CCHS ¼ Canadian Community Health Survey.
ETS-exposed homes (n ¼ 16 179) %
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Table 2 Unadjusted ORs (95%CI) for home ETS exposure for the entire sample (column 2) and for the subgroup of only households with children (column 3), determined from the Canadian Community Health Survey 2009–2010 Subgroup: ETS exposure in households with children ,12 years OR (95%CI)
Households with ETS exposure OR (95%CI) All households Households without children (all 12 years) Households with children (at least 1 ,12 years)
Reference 0.83 (0.80–0.87)
— —
Subgroup: households with children Older child households (all 6 years, ,12 years) Young child households (at least 1 ,6 years)
— —
Reference 0.98 (0.91–1.05)
Racial origin (respondent)* White Visible minority
Reference 0.79 (0.75–0.82)
Reference 0.82 (0.76–0.89)
2.11 (1.96–2.27) 2.09 (1.98–2.21) 1.81 (1.68–1.95) Reference
5.51 (4.62–6.56) 2.51 (2.26–2.82) 2.58 (2.21–3.02) Reference
2.57 (2.38–2.78) 1.96 (1.86–2.06) 1.66 (1.58–1.74) 1.51 (1.44–1.59) Reference
3.67 (3.18–4.22) 2.92 (2.63–3.24) 1.96 (1.76–2.18) 1.65 (1.49–1.83) Reference
Household education Less than secondary Secondary graduation Some post-secondary Post-secondary graduation Household income, Canadian dollars ,20 000 20 000–39 999 40 000–59 999 60 000–79 999 80 000
*According to categories as provided by the CCHS. OR ¼ odds ratio; CI ¼ confidence interval; ETS ¼ environmental tobacco smoke; CCHS ¼ Canadian Community Health Survey.
shown) did not alter the OR for home ETS compared to the unadjusted OR. The sensitivity analysis of the unadjusted OR for home ETS exposure calculated on the sample including all those with unstated household education and income (OR 0.83, 95%CI 0.80– 0.86) was no different from the unadjusted estimate on the final primary analytic sample that excluded respondents with unstated household education and income (OR 0.83, 95%CI 0.80–0.87). Subgroup comparison The bivariable analysis of the subgroup of only
households with children (n ¼ 17 834), comparing households with young children and households with only older children for the probability of home ETS exposure, showed no difference in young child households relative to older child households (unadjusted OR 0.98, 95%CI 0.91–1.05) (Table 2, column 3). Stratification by household education and income did not modify this association in the subgroup (Table 3, columns 4 & 5). Multivariable analysis adjusting for education, income, and racial origin (adjusted OR 0.97, 95%CI 0.90–1.04; model not shown) was no different from the unadjusted association. The
Table 3 Stratified analysis for the probability of home ETS exposure stratified by highest household education and household income, for the entire sample (columns 2 & 3) and the subgroup of only households with children ,12 years (columns 4 & 5) Households with ETS exposure* (n ¼ 66 631) Stratum n (%) Household education ,Secondary Secondary graduate Some post-secondary Post-secondary graduate
4558 7146 3309 51 618
Unadjusted OR (95%CI)
Subgroup: ETS exposure in households with children ,12 years† (n ¼17 834) Stratum n (%)
Unadjusted OR (95%CI)
(4.8) (9.4) (5.1) (80.8)
2.56 0.99 1.24 0.78
(2.12–3.10) (0.88–1.13) (1.04–1.47) (0.74–0.81)
650 1508 845 14 831
(3.0) (8.0) (4.1) (84.9)
1.09 1.13 1.37 0.94
(0.77–1.54) (0.91–1.41) (1.01–1.87) (0.86–1.02)
Household income, Canadian dollars ,20 000 3242 (5.0) 20 000–39 999 11 581 (14.8) 40 000–59 999 12 462 (16.7) 60 000–79 999 11 417 (17.3) 80 000 27 929 (46.2)
1.13 1.19 0.88 0.78 0.70
(0.97–1.32) (1.08–1.31) (0.78–0.97) (0.71–0.86) (0.65–0.75)
1071 2372 2757 3050 8584
(5.5) (13.4) (14.8) (17.7) (48.6)
1.20 0.94 0.99 1.15 0.87
(0.93–1.55) (0.79–1.18) (0.83–1.18) (0.97–1.36) (0.77–0.98)
*For the entire sample, OR is for households with children aged ,12 years relative to households without children. † For subgroup comparison of only households with children aged ,12 years, OR is for households with young children (at least one child aged ,6 years) relative to households with only older children (all children aged 6–11 years). ETS ¼ environmental tobacco smoke; OR ¼ odds ratio; CI ¼ confidence interval.
Home tobacco smoke exposure in children
estimate of the OR in the subgroup sensitivity analysis (OR 0.96, 95%CI 0.90–1.04) was no different from the OR obtained on the analytic subgroup sample.
DISCUSSION A quarter of Canadian households without children and almost 22% of households with children experience home ETS exposure, according to our broadened definition that includes any smokers living in the household, irrespective of whether they smoke within the house. Households with children were at best only marginally less likely than households without children to experience home ETS exposure. Visible minority households and households in the highest education and income categories were protective against ETS exposure. Households with children aged ,12 years in the lowest education category were at substantially higher risk than households without children, and both household education and income showed a significant dose-response relationship with home ETS exposure. There were no differences in ETS exposure between households with younger children compared to households with only older children. It is widely accepted that smoking during pregnancy has consequences for the fetus and young child and that ETS exposure has health implications for the non-smoker. This study points to a gap in the broader public’s recognition of the detrimental effects of ETS exposure during childhood.3,11 If adults were aware of the risks of second- and third-hand smoke to young children specifically, one would expect that home ETS exposure would occur less often in homes with young children compared to homes with only older or no children. Smoking in Canada is highest among males and females aged 20–34 years (30% and 24%, respectively), which is also the age group most likely to be parents of young children.1 This study was not able to ascertain parental age, but it will be valuable for identification of target groups to determine whether younger parental age and home ETS exposure in young children are associated. This study did not quantitatively measure ETS exposure, which may be lower in homes with young children if smokers alter their smoking behavior in an attempt to protect the young child. However, no level of ETS exposure is considered safe, and young children are vulnerable to ETS exposure through third-hand smoke.3,6,7 Home smoking bans and other attempts to encourage smokers to avoid smoking in the presence of children may lead the public to believe that this is sufficient to completely protect their children from the effects of ETS exposure.12 Public health messaging needs to be clear that only complete cessation of smoking by adults living with children will eliminate the risks associated with home ETS exposure during childhood.
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As young children are less able to exert control over their environment or influence the behavior of smoking adult members of their household than non-smoking adults, it is not surprising that children do not experience substantially less home ETS exposure than adults.7 Legislation for smoke-free environments combined with education is recommended as the most effective strategy to eliminate secondhand smoke exposure. Alternatives such as voluntary policies, education alone, or separation of smokers and non-smokers within the same air space do not eliminate ETS exposure.12 To reduce the burden of tobacco smoke exposure in children it must be understood how to effectively deliver messages to adults and parents across the socio-economic spectrum of children’s vulnerability to ETS. The presence of a statistical interaction between children in the home and each of household education and income was considered. However, it is possible that household education and income are proxies for other social factors known to be directly associated with increased home ETS exposure in children, specifically the number of adults in the home and homes headed by someone other than the child’s parents, both un-measurable in the CCHS sample.4,5 As it was unable to adjust for these confounders of household education and income, a multivariable model including interactions between children in the household and household education and income was not performed.9 Alternatively, the stratified analysis demonstrating effect modification of the association between children and home ETS exposure by strata of household education and income is able to demonstrate and identify groups in which children are at high risk for home ETS exposure.9,10 The distribution of household income and education in the study sample compared to the full CCHS sample differed considerably. This is explained by the exclusion of 27.1% of CCHS respondents living alone, who were an older population than the study sample. Although our study may not be representative of the general Canadian population, it is a large evaluation of households at risk of ETS exposure, i.e., households with more than one occupant that specifically considers children. The exclusion of respondents with unstated household education and income could have biased this analysis, although it is reassuring that the strength of the associations in the sensitivity analyses were no different from the original estimates. This study did not hypothesise a causal direction to the association, and it was thus not limited by the cross-sectional nature of the CCHS. Because households, and not individual children, were the unit of analysis, the prevalence of home ETS exposure could not be estimated. However, this is the first Canadian evaluation of the extent of ETS exposure in households with children aged ,12 years, and it is consistent with US findings that adults
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living with children are only slightly, as opposed to substantially, less likely to smoke than adults not living with children, that low household education and household income are associated with greater home ETS exposure, and that White children experience more home ETS exposure than children of other racial origins.4,5,13
CONCLUSION To accurately determine the burden of home ETS exposure in children, the prevalence of exposed children needs to be determined using a broader definition of home ETS exposure that includes exposure to third-hand smoke. In the interim, this study suggests that young children may be exposed to ETS in the home as much as older children and only marginally less exposed than non-smoking adolescents and adults in households with higher education and income. This has implications for educational messaging across the socio-economic spectrum with regard to home ETS exposure and its detrimental effects during childhood that are generalisable beyond Canada. Acknowledgements ALS would like to thank M Koehoorn and the SPPH504 class of 2012 at the School of Population and Public Health, University of British Columbia, for their generous and insightful guidance and comments on the initial draft of this paper. ALS receives research trainee funding from the Canadian Institutes of Health Research as the Canada-Hope Scholar. JAB has a career scholar award from the Michael Smith Foundation for Health Research. Conflict of interest: none to declare.
References 1 Janz T. Current smoking trends. Ottawa, ON, Canada: Statistics Canada, 2012. www.statcan.gc.ca/pub/82-624-x/ 2012001/article/11676-eng.htm Accessed January 2014.
2 Statistics Canada. Exposure to secondhand smoke at home by age and sex group. Ottawa, ON, Canada: Statistics Canada, 2012. www.statcan.gc.ca/tables-tableaux/sum-som/l01/cst01/ health95b-eng.htm Accessed January 2014. 3 US Department of Health and Human Services. The health consequences of involuntary exposure to tobacco smoke: a report of the Surgeon General. Washington DC, USA: Department of Health and Human Services, Centers for Disease Control and Prevention, Coordinating Center for Health Promotion, National Center for Chronic Disease Prevention and Health Promotion, Office on Smoking and Health, 2006. www.cdc.gov/tobacco/data_statistics/sgr/2006/ index.htm Accessed January 2014. 4 Singh G K, Siahpush M, Kogan M D. Disparities in children’s exposure to environmental tobacco smoke in the United States, 2007. Pediatrics 2010; 126: 4–13. 5 King K, Martynenko M, Bergman M H, Liu Y-H, Winickoff J P, Weitzman M. Family composition and children’s exposure to adult smokers in their homes. Pediatrics 2009; 123: e559–64. 6 Matt G E. Households contaminated by environmental tobacco smoke: sources of infant exposures. Tob Control 2004; 13: 29– 37. 7 Bearer C F. Hazards: how children are different from adults. Future Child 2005; 5: 11–26. 8 Statistics Canada. Canadian Community Health Survey (CCHS). Annual component. User guide 2010 and 2009–2010 Microdata files. Ottawa, ON, Canada: Statistics Canada, 2011. 9 Van der Weele T J. On the distinction between interaction and effect modification. Epidemiology 2009; 20: 863–71. 10 Szklo M, Nieto F J. Epidemiology beyond the basics. 3rd ed. Chapter 6: Defining and assessing heterogeneity of effects: interaction. Burlington, MA, USA: Jones & Bartlett, 2007: p 211. 11 Herrmann M, King K, Weitzman M. Prenatal tobacco smoke and postnatal secondhand smoke exposure and child neurodevelopment. Curr Opin Pediatr 2008; 20: 184–190. 12 World Health Organization. Protection from exposure to second-hand tobacco smoke. Policy recommendations. Geneva, Switzerland. WHO, 2007. http://whqlibdoc.who.int/ publications/2007/9789241563413_eng.pdf Accessed January 2014. 13 Holtby S, Zahnd E, Grant D, Park R. Children’s exposure to secondhand smoke: nearly one million affected in California. Policy Brief UCLA Cent Health Policy Res 2011; (PB2011-9): 1–8.
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RESUME C O N T E X T E : Les enfants vivant avec un fumeur sont davantage expos e´ s a` la fum e´ e de tabac dans l’environnement (ETS) mˆeme quand le fumeur e´ vite de fumer a` l’int´erieur de la maison, par comparaison aux enfants ne vivant pas avec un fumeur. Etant donn´es les risques encourus par les enfants, nous avons e´ mis l’hypoth`ese que les foyers comportant des enfants e´ taient moins enclins que ceux sans enfants a` eˆ tre expos´es a` l’ETS a` domicile. S C H E´ M A : Analyse transversale de l’enquˆete de sant´e communautaire canadienne de 2009–2010 a` la recherche d’une association entre la pr´esence d’enfants ag´ ˆ es de ,12 ans dans le foyer et l’exposition a` l’ETS a` domicile grace ˆ a` une r´egression logistique et en tenant compte du niveau d’´education et de revenu comme facteurs de confusion ou modificateurs d’impact.
L’analyse d’un sous-groupe a permis de comparer les foyers ou` vivaient des jeunes enfants (au moins un enfant ag´ ˆ e de ,6 ans) et ceux ou` vivaient des enfants plus ag´ ˆ es (tous les enfants ag´ ˆ es de 6 a` 11 ans). R E´ S U L T A T S : Des 66 631 foyers inclus, l’ETS a` domicile concernait 25% des foyers sans enfants et 22% des foyers avec enfants. Les foyers avec enfants e´ taient un peu moins enclins a` eˆ tre expos´es a` l’ETS que les foyers avec enfants (OR 0,83 ; IC95% 0,80–0,87). Il existait une variation de l’ETS en fonction du niveau d’´education et de revenu. Par contre, il n’existait pas de variation en fonction de l’age ˆ des enfants (OR 0,98 ; IC95% 0,91–1,05). C O N C L U S I O N : Les foyers avec enfants sont moins enclins a` eˆ tre expos´es a` l’ETS, mais seulement de fa¸con marginale. RESUMEN
M A R C O D E R E F E R E N C I A : Los ninos ˜ que viven con un fumador se encuentran ma´s expuestos al humo del tabaco en el ambiente (ETS) que los ninos sin esta ˜ convivencia, aunque la persona evite fumar al interior del hogar. Dados los riesgos de esta exposicion ´ en la infancia, se planteo´ la hipotesis ´ de que es menos probable que exista una exposicion ´ al humo del tabaco en los hogares donde viven ninos ˜ que en los hogares sin ninos. ˜ M E´ T O D O : Se llevo ´ a cabo un ana´lisis transversal de la Encuesta de Salud Comunitaria del Canada´ en el 2009 y el 2010 con el fin de estudiar la asociacion ´ entre los ninos de edad de ,12 anos de los hogares y la ETS, ˜ ˜ mediante un modelo de regresion ´ log´ıstica; se definieron como factores de confusion ´ o modificadores del efecto la educacion ´ en el hogar y el ingreso. Se practico´ un ana´lisis
en subgrupos en el cual se compararon los hogares con ninos ˜ menores (como m´ınimo un nino ˜ de edad de ,6 anos) con los hogares con ninos mayores (solo ninos ˜ ˜ ˜ entre los 6 anos ˜ y los 11 anos ˜ de edad). R E S U L T A D O S : Se incluyeron 66 631 hogares en el ana´lisis; ocurrio´ el ETS en el 25% de los hogares sin ninos Fue menos ˜ y en el 22% de los hogares con ninos. ˜ probable que ocurriese esta exposicion ´ en los hogares con ninos ˜ (OR 0,83; IC95% 0,80–0,87). Se observo´ una modificacion ´ del efecto por la educacion ´ y los ingresos. No se observo´ diferencia del ETS entre los hogares con ninos ˜ menores y con ninos ˜ mayores (OR 0,98; IC95% 0,91–1,05). ´ N : La diferencia de la probabilidad del CONCLUSIO ETS en los hogares con ninos ˜ y los hogares donde no viven ninos ˜ es m´ınima.
Home environmental tobacco smoke exposure in Canadian children A. L. Slogrove,*† J. A. Bettinger‡ *School of Population & Public Health, Faculty of Medicine, University of British Columbia, Vancouver, Canada; † Department of Paediatrics and Child Health, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa; ‡Vaccine Evaluation Center, Department of Pediatrics, BC Children’s Hospital, University of British Columbia, Vancouver, Canada SUMMARY BACKGROUND:
Children living with a smoker experience increased environmental tobacco smoke (ETS) exposure, even when the smoker refrains from smoking inside the house, compared to children not living with a smoker. Given the risks of ETS in children, it was hypothesized that households with children are less likely than those without children to experience home ETS exposure. D E S I G N : Cross-sectional analysis of the Canadian Community Health Survey 2009–2010 for the association between children aged ,12 years in the household and home ETS exposure, using logistic regression and considering household education and income as confounders or effect modifiers. A subgroup analysis was conducted comparing younger child households (at least
one child aged ,6 years) to older child households (only children aged 6–11 years). R E S U LT S : Of 66 631 households included, home ETS exposure occurred in 25% of households without children and 22% of households with children. Households with children were less likely than those without children to experience ETS exposure (OR 0.83, 95%CI 0.80–0.87). Effect modification by education and income was observed. No difference was observed in ETS exposure between older child and younger child households (OR 0.98, 95%CI 0.91–1.05). C O N C L U S I O N : Households with children are marginally less likely than households without children to experience home ETS exposure. K E Y W O R D S : environmental tobacco smoke; tobacco; secondhand smoke
CANADA has seen consistent reductions in smoking and environmental tobacco smoke (ETS) exposure, with only 5.5% of adult Canadians reporting home ETS exposure.1,2 This exposure varies according to age, with 12.6% of Canadians aged 12–19 years who are exposed compared to 3–6% of those aged 20 years.2 There are no published Canadian estimates of home ETS exposure in children aged ,12 years. In addition to the long-term consequences of ETS experienced by the general population (e.g., lung cancer and heart disease), children exposed to ETS experience higher rates of sudden infant death syndrome, respiratory tract and ear infections, and severe asthma during childhood.3 In the United States, ETS exposure in children aged ,12 years is associated with low socio-economic status, lower levels of parental education, and homes headed by someone other than the parents of the child.4 After controlling for family income and the number of adults in the home, White children in the United
States were more likely to live with a smoker than Hispanic, Black, or Asian/Pacific Islander children.5 The above estimates of ETS exposure were based solely on exposures associated with smokers who smoked inside the house.2,4 In the case of infants and young children, ETS exposure estimates that exclude smokers who live but do not smoke inside the house underestimate the number of children at risk of the negative effects of ETS. Infants are particularly vulnerable to third-hand smoke trapped in hair, skin, home furnishings, and dust released slowly into the atmosphere over time.6,7 Infants living in homes with smoking parents who diligently took precautions to avoid exposing their infants to ETS by only smoking outdoors still experienced levels of exposure five to seven times higher than infants not living with a smoker.6 Given the well-publicized risks of ETS, one would expect that adults in households with young children would be less likely to smoke than adults living in households with older children or no children.
Correspondence to: A L Slogrove, Vaccine Evaluation Center, A5-173 950 West 28th Ave, Vancouver V5Z 4H4, BC, Canada. Tel: (þ1) 604 875 2422. e-mail: [email protected] Article submitted 2 September 2013. Final version accepted 17 December 2013.
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Contrary to this expectation, it was observed in the United States that more adults living with children smoke compared to adults who do not live with children (23% vs. 21%), and 34% of children live with an adult smoker compared to 7% of nonsmoking adults living with an adult smoker.5 These observations suggest a lack of awareness among adults of the risks of ETS exposure to children specifically. This study examined the association between the presence of children in the home and home ETS exposure with the hypothesis that households with children would be less likely than households without children to experience home ETS exposure.
STUDY POPULATION AND METHODS Study design This was a cross-sectional study using the Public Use Microdata File (PUMF) for the 2009–2010 Canadian Community Health Survey (CCHS), an annual survey performed by Statistics Canada that collects nationally representative health-related data. The Canadian population aged 12 years was randomly sampled and participation was voluntary. The sample was limited to a single respondent per household. A response rate of 72.3% was achieved. Approximately 2% of the population was not represented by the 2009–2010 CCHS.8 All CCHS respondents provide informed consent for participation and the PUMF made available by Statistics Canada was accessed in accordance with the University of British Columbia Policy #89 (clause 7.10). Study sample The 2009–2010 CCHS included 124 188 respondents. Excluded from the sample were respondents living alone (27.1%), those with an unknown/unstated living arrangement (4.5%), unstated smoking status (0.5%), or non-smoking respondents with unknown/unstated home ETS exposure (0.5%). The non-response rates in the remaining sample for total household income and household education were respectively 17.3% and 7.6%. Only respondents with valid responses for household education and income were included in the final analytic sample of 66 631 respondents, each representing a single household. This provided an adequate sample size at alpha 5% and beta 10% to detect a 2% difference in the proportion of households with home ETS exposure between younger child households (21%), older child households (23%), and households without children (25%). Variable definitions The primary outcome variable was binary: 1) home ETS exposure – at least one smoker living in the household, irrespective of whether the smoker was reported to smoke inside the house, or 2) no home
ETS exposure – no smokers living in the household. The primary explanatory variable was the presence of children in the household: 1) households without children, i.e., no person aged ,12 years, and 2) households with children, i.e., at least one person aged ,12 years. Additional socio-economic variables evaluated included racial origin of the respondent (as a proxy for the household), either White or visible minority as categorized by the CCHS, highest level of household education, and household income. Analysis plan Descriptive statistics were calculated as frequencies for each variable and associations were determined by logistic regression with the degree of precision around point estimates represented by 95% confidence intervals (CIs). The primary analysis evaluated the association between home ETS exposure and households with children compared to households without children, described with an unadjusted odds ratio (OR). Third level variables for consideration as either confounders or effect modifiers were determined conceptually and based on previous evidence, and included racial origin, highest level of household education, and household income as defined by the CCHS. Differences in home ETS exposure across Canadian provinces were evaluated. To differentiate between confounding and effect modification, stratified analyses were conducted. The concept of effect modification as proposed by van der Weele was utilized, distinguishing effect modification from interaction (effect modification describes the association between the primary exposure and outcome when the primary exposure is conditioned on a secondary exposure; interaction describes the association jointly between the primary and secondary exposure on the outcome).9 Multivariable logistic regression was used to adjust for confounding according to the absence of effect modification.10 The Cochran-Armitage trend test was performed for variables that appeared to have a dose-response relationship with the outcome (household education and income). Due to the high proportion of respondents with unstated household education and income excluded from the final primary analytic sample, a sensitivity analysis was conducted for the unadjusted OR of home ETS exposure. The sensitivity analysis sample included all respondents with unstated household education and income (n ¼ 84 336) compared to the final primary analytic sample (n ¼ 66 631). A subgroup analysis of only those households with children aged ,12 years evaluated whether the age of children in the household was differentially associated with home ETS exposure. Households with children were categorized for comparison into two subgroups: 1) young child households, i.e., at least one child aged ,6 years, or 2) older child households, i.e., all children
Home tobacco smoke exposure in children
aged 6 years. Similar to the primary analysis plan above, the bivariable association for this subgroup analysis was described using an unadjusted OR; a stratified analysis was conducted to differentiate between confounding and effect modification by household education and income. In the absence of effect modification, a multivariable logistic regression model was determined adjusting for racial origin, household education, and household income; a sensitivity analysis including respondents with unstated household education and income was conducted. Probability weights calculated from the masterweights supplied by Statistics Canada were applied to each respondent for calculation of all proportions and regression analyses to maintain weighting of respondents according to the CCHS sampling strategy while calculating appropriate estimates of precision according to the sample size. Statistical analysis was conducted using SAS, version 9.3 (Statistical Analysis Software Institute, Cary, NC, USA).
RESULTS Description of study sample Of the 66 631 Canadian households included in this study, 81.5% were represented by a respondent of White racial origin, 80.8% had an occupant with post-secondary education graduation, and the majority (53.8%) had an annual household income of ,80 000 Canadian dollars (Table 1). This is compared to the general Canadian population as represented by the complete CCHS sample, including 77.4% of households represented by a respondent of White racial origin, 70.2% with post-secondary
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graduation, and 66.8% of households with an income of ,80 000 Canadian dollars. Almost a quarter (24.0%) of the households in the study sample experienced home ETS exposure, 26.5% had at least one child aged ,12 years, and 14.7% at least one child aged ,6 years. More households without children than households with children experienced home ETS exposure (25% vs. 21.6%). Provincial variation in home ETS exposure ranged from 18.2% to 39.5%. Primary comparison Households with children were 17% less likely to experience home ETS exposure than households without children (OR 0.83, 95%CI 0.80–0.87) (Table 2, column 2). Stratification by household education and income modified this association (Table 3, columns 2 & 3). The highest education and income strata showed some protective effects for households with children (OR 0.78, 95%CI 0.74–0.81 and OR 0.70, 95%CI 0.65–0.75, respectively). However, the lowest education and lowest income strata showed a 2.56 (95%CI 2.12–3.10) and a 1.13 (95%CI 0.97– 1.32) times greater probability, respectively, of home ETS exposure for households with children. Due to the presence of effect modification by household education and income, multivariable logistic regression adjusting for these variables was not performed. Increasing household education and income were both significantly associated (P , 0.0001) with no home ETS exposure in the full study sample and in both exposure groups (households with and without children), showing a dose-response relationship. Adjustment for province of residence (model not
Table 1 Distribution of characteristics comparing ETS unexposed homes and ETS-exposed homes in the CCHS, 2009–2010 (weighted percentages) Total study sample (n ¼ 66 631) n
%
ETS-unexposed homes (n ¼ 50 452) %
Children in the household Households without children (all 12 years) Older child households (all 6 – 11 years) Younger child households (at least 1 – ,6 years)
48 797 7173 10 661
73.4 11.8 14.7
72.6 12.2 15.2
76.1 10.8 13.2
Racial origin (respondent)* White Visible minority
58 078 8553
81.5 18.5
80.7 19.3
84.2 15.8
Household education Less than secondary Secondary graduation Some post-secondary Post-secondary graduation
4558 7146 3309 51 618
4.8 9.4 5.1 80.8
4.0 7.9 4.5 83.6
7.3 14.1 7.0 71.7
Household income, Canadian dollars ,20 000 20 000–39 999 40 000–59 999 60 000–79 999 80 000
3242 11 581 12 462 11 417 27 929
5.0 14.8 16.7 17.3 46.2
4.1 13.5 16.0 16.9 49.5
7.6 19.1 19.1 18.5 35.7
*According to categories as provided by the CCHS. ETS ¼ environmental tobacco smoke; CCHS ¼ Canadian Community Health Survey.
ETS-exposed homes (n ¼ 16 179) %
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Table 2 Unadjusted ORs (95%CI) for home ETS exposure for the entire sample (column 2) and for the subgroup of only households with children (column 3), determined from the Canadian Community Health Survey 2009–2010 Subgroup: ETS exposure in households with children ,12 years OR (95%CI)
Households with ETS exposure OR (95%CI) All households Households without children (all 12 years) Households with children (at least 1 ,12 years)
Reference 0.83 (0.80–0.87)
— —
Subgroup: households with children Older child households (all 6 years, ,12 years) Young child households (at least 1 ,6 years)
— —
Reference 0.98 (0.91–1.05)
Racial origin (respondent)* White Visible minority
Reference 0.79 (0.75–0.82)
Reference 0.82 (0.76–0.89)
2.11 (1.96–2.27) 2.09 (1.98–2.21) 1.81 (1.68–1.95) Reference
5.51 (4.62–6.56) 2.51 (2.26–2.82) 2.58 (2.21–3.02) Reference
2.57 (2.38–2.78) 1.96 (1.86–2.06) 1.66 (1.58–1.74) 1.51 (1.44–1.59) Reference
3.67 (3.18–4.22) 2.92 (2.63–3.24) 1.96 (1.76–2.18) 1.65 (1.49–1.83) Reference
Household education Less than secondary Secondary graduation Some post-secondary Post-secondary graduation Household income, Canadian dollars ,20 000 20 000–39 999 40 000–59 999 60 000–79 999 80 000
*According to categories as provided by the CCHS. OR ¼ odds ratio; CI ¼ confidence interval; ETS ¼ environmental tobacco smoke; CCHS ¼ Canadian Community Health Survey.
shown) did not alter the OR for home ETS compared to the unadjusted OR. The sensitivity analysis of the unadjusted OR for home ETS exposure calculated on the sample including all those with unstated household education and income (OR 0.83, 95%CI 0.80– 0.86) was no different from the unadjusted estimate on the final primary analytic sample that excluded respondents with unstated household education and income (OR 0.83, 95%CI 0.80–0.87). Subgroup comparison The bivariable analysis of the subgroup of only
households with children (n ¼ 17 834), comparing households with young children and households with only older children for the probability of home ETS exposure, showed no difference in young child households relative to older child households (unadjusted OR 0.98, 95%CI 0.91–1.05) (Table 2, column 3). Stratification by household education and income did not modify this association in the subgroup (Table 3, columns 4 & 5). Multivariable analysis adjusting for education, income, and racial origin (adjusted OR 0.97, 95%CI 0.90–1.04; model not shown) was no different from the unadjusted association. The
Table 3 Stratified analysis for the probability of home ETS exposure stratified by highest household education and household income, for the entire sample (columns 2 & 3) and the subgroup of only households with children ,12 years (columns 4 & 5) Households with ETS exposure* (n ¼ 66 631) Stratum n (%) Household education ,Secondary Secondary graduate Some post-secondary Post-secondary graduate
4558 7146 3309 51 618
Unadjusted OR (95%CI)
Subgroup: ETS exposure in households with children ,12 years† (n ¼17 834) Stratum n (%)
Unadjusted OR (95%CI)
(4.8) (9.4) (5.1) (80.8)
2.56 0.99 1.24 0.78
(2.12–3.10) (0.88–1.13) (1.04–1.47) (0.74–0.81)
650 1508 845 14 831
(3.0) (8.0) (4.1) (84.9)
1.09 1.13 1.37 0.94
(0.77–1.54) (0.91–1.41) (1.01–1.87) (0.86–1.02)
Household income, Canadian dollars ,20 000 3242 (5.0) 20 000–39 999 11 581 (14.8) 40 000–59 999 12 462 (16.7) 60 000–79 999 11 417 (17.3) 80 000 27 929 (46.2)
1.13 1.19 0.88 0.78 0.70
(0.97–1.32) (1.08–1.31) (0.78–0.97) (0.71–0.86) (0.65–0.75)
1071 2372 2757 3050 8584
(5.5) (13.4) (14.8) (17.7) (48.6)
1.20 0.94 0.99 1.15 0.87
(0.93–1.55) (0.79–1.18) (0.83–1.18) (0.97–1.36) (0.77–0.98)
*For the entire sample, OR is for households with children aged ,12 years relative to households without children. † For subgroup comparison of only households with children aged ,12 years, OR is for households with young children (at least one child aged ,6 years) relative to households with only older children (all children aged 6–11 years). ETS ¼ environmental tobacco smoke; OR ¼ odds ratio; CI ¼ confidence interval.
Home tobacco smoke exposure in children
estimate of the OR in the subgroup sensitivity analysis (OR 0.96, 95%CI 0.90–1.04) was no different from the OR obtained on the analytic subgroup sample.
DISCUSSION A quarter of Canadian households without children and almost 22% of households with children experience home ETS exposure, according to our broadened definition that includes any smokers living in the household, irrespective of whether they smoke within the house. Households with children were at best only marginally less likely than households without children to experience home ETS exposure. Visible minority households and households in the highest education and income categories were protective against ETS exposure. Households with children aged ,12 years in the lowest education category were at substantially higher risk than households without children, and both household education and income showed a significant dose-response relationship with home ETS exposure. There were no differences in ETS exposure between households with younger children compared to households with only older children. It is widely accepted that smoking during pregnancy has consequences for the fetus and young child and that ETS exposure has health implications for the non-smoker. This study points to a gap in the broader public’s recognition of the detrimental effects of ETS exposure during childhood.3,11 If adults were aware of the risks of second- and third-hand smoke to young children specifically, one would expect that home ETS exposure would occur less often in homes with young children compared to homes with only older or no children. Smoking in Canada is highest among males and females aged 20–34 years (30% and 24%, respectively), which is also the age group most likely to be parents of young children.1 This study was not able to ascertain parental age, but it will be valuable for identification of target groups to determine whether younger parental age and home ETS exposure in young children are associated. This study did not quantitatively measure ETS exposure, which may be lower in homes with young children if smokers alter their smoking behavior in an attempt to protect the young child. However, no level of ETS exposure is considered safe, and young children are vulnerable to ETS exposure through third-hand smoke.3,6,7 Home smoking bans and other attempts to encourage smokers to avoid smoking in the presence of children may lead the public to believe that this is sufficient to completely protect their children from the effects of ETS exposure.12 Public health messaging needs to be clear that only complete cessation of smoking by adults living with children will eliminate the risks associated with home ETS exposure during childhood.
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As young children are less able to exert control over their environment or influence the behavior of smoking adult members of their household than non-smoking adults, it is not surprising that children do not experience substantially less home ETS exposure than adults.7 Legislation for smoke-free environments combined with education is recommended as the most effective strategy to eliminate secondhand smoke exposure. Alternatives such as voluntary policies, education alone, or separation of smokers and non-smokers within the same air space do not eliminate ETS exposure.12 To reduce the burden of tobacco smoke exposure in children it must be understood how to effectively deliver messages to adults and parents across the socio-economic spectrum of children’s vulnerability to ETS. The presence of a statistical interaction between children in the home and each of household education and income was considered. However, it is possible that household education and income are proxies for other social factors known to be directly associated with increased home ETS exposure in children, specifically the number of adults in the home and homes headed by someone other than the child’s parents, both un-measurable in the CCHS sample.4,5 As it was unable to adjust for these confounders of household education and income, a multivariable model including interactions between children in the household and household education and income was not performed.9 Alternatively, the stratified analysis demonstrating effect modification of the association between children and home ETS exposure by strata of household education and income is able to demonstrate and identify groups in which children are at high risk for home ETS exposure.9,10 The distribution of household income and education in the study sample compared to the full CCHS sample differed considerably. This is explained by the exclusion of 27.1% of CCHS respondents living alone, who were an older population than the study sample. Although our study may not be representative of the general Canadian population, it is a large evaluation of households at risk of ETS exposure, i.e., households with more than one occupant that specifically considers children. The exclusion of respondents with unstated household education and income could have biased this analysis, although it is reassuring that the strength of the associations in the sensitivity analyses were no different from the original estimates. This study did not hypothesise a causal direction to the association, and it was thus not limited by the cross-sectional nature of the CCHS. Because households, and not individual children, were the unit of analysis, the prevalence of home ETS exposure could not be estimated. However, this is the first Canadian evaluation of the extent of ETS exposure in households with children aged ,12 years, and it is consistent with US findings that adults
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living with children are only slightly, as opposed to substantially, less likely to smoke than adults not living with children, that low household education and household income are associated with greater home ETS exposure, and that White children experience more home ETS exposure than children of other racial origins.4,5,13
CONCLUSION To accurately determine the burden of home ETS exposure in children, the prevalence of exposed children needs to be determined using a broader definition of home ETS exposure that includes exposure to third-hand smoke. In the interim, this study suggests that young children may be exposed to ETS in the home as much as older children and only marginally less exposed than non-smoking adolescents and adults in households with higher education and income. This has implications for educational messaging across the socio-economic spectrum with regard to home ETS exposure and its detrimental effects during childhood that are generalisable beyond Canada. Acknowledgements ALS would like to thank M Koehoorn and the SPPH504 class of 2012 at the School of Population and Public Health, University of British Columbia, for their generous and insightful guidance and comments on the initial draft of this paper. ALS receives research trainee funding from the Canadian Institutes of Health Research as the Canada-Hope Scholar. JAB has a career scholar award from the Michael Smith Foundation for Health Research. Conflict of interest: none to declare.
References 1 Janz T. Current smoking trends. Ottawa, ON, Canada: Statistics Canada, 2012. www.statcan.gc.ca/pub/82-624-x/ 2012001/article/11676-eng.htm Accessed January 2014.
2 Statistics Canada. Exposure to secondhand smoke at home by age and sex group. Ottawa, ON, Canada: Statistics Canada, 2012. www.statcan.gc.ca/tables-tableaux/sum-som/l01/cst01/ health95b-eng.htm Accessed January 2014. 3 US Department of Health and Human Services. The health consequences of involuntary exposure to tobacco smoke: a report of the Surgeon General. Washington DC, USA: Department of Health and Human Services, Centers for Disease Control and Prevention, Coordinating Center for Health Promotion, National Center for Chronic Disease Prevention and Health Promotion, Office on Smoking and Health, 2006. www.cdc.gov/tobacco/data_statistics/sgr/2006/ index.htm Accessed January 2014. 4 Singh G K, Siahpush M, Kogan M D. Disparities in children’s exposure to environmental tobacco smoke in the United States, 2007. Pediatrics 2010; 126: 4–13. 5 King K, Martynenko M, Bergman M H, Liu Y-H, Winickoff J P, Weitzman M. Family composition and children’s exposure to adult smokers in their homes. Pediatrics 2009; 123: e559–64. 6 Matt G E. Households contaminated by environmental tobacco smoke: sources of infant exposures. Tob Control 2004; 13: 29– 37. 7 Bearer C F. Hazards: how children are different from adults. Future Child 2005; 5: 11–26. 8 Statistics Canada. Canadian Community Health Survey (CCHS). Annual component. User guide 2010 and 2009–2010 Microdata files. Ottawa, ON, Canada: Statistics Canada, 2011. 9 Van der Weele T J. On the distinction between interaction and effect modification. Epidemiology 2009; 20: 863–71. 10 Szklo M, Nieto F J. Epidemiology beyond the basics. 3rd ed. Chapter 6: Defining and assessing heterogeneity of effects: interaction. Burlington, MA, USA: Jones & Bartlett, 2007: p 211. 11 Herrmann M, King K, Weitzman M. Prenatal tobacco smoke and postnatal secondhand smoke exposure and child neurodevelopment. Curr Opin Pediatr 2008; 20: 184–190. 12 World Health Organization. Protection from exposure to second-hand tobacco smoke. Policy recommendations. Geneva, Switzerland. WHO, 2007. http://whqlibdoc.who.int/ publications/2007/9789241563413_eng.pdf Accessed January 2014. 13 Holtby S, Zahnd E, Grant D, Park R. Children’s exposure to secondhand smoke: nearly one million affected in California. Policy Brief UCLA Cent Health Policy Res 2011; (PB2011-9): 1–8.
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RESUME C O N T E X T E : Les enfants vivant avec un fumeur sont davantage expos e´ s a` la fum e´ e de tabac dans l’environnement (ETS) mˆeme quand le fumeur e´ vite de fumer a` l’int´erieur de la maison, par comparaison aux enfants ne vivant pas avec un fumeur. Etant donn´es les risques encourus par les enfants, nous avons e´ mis l’hypoth`ese que les foyers comportant des enfants e´ taient moins enclins que ceux sans enfants a` eˆ tre expos´es a` l’ETS a` domicile. S C H E´ M A : Analyse transversale de l’enquˆete de sant´e communautaire canadienne de 2009–2010 a` la recherche d’une association entre la pr´esence d’enfants ag´ ˆ es de ,12 ans dans le foyer et l’exposition a` l’ETS a` domicile grace ˆ a` une r´egression logistique et en tenant compte du niveau d’´education et de revenu comme facteurs de confusion ou modificateurs d’impact.
L’analyse d’un sous-groupe a permis de comparer les foyers ou` vivaient des jeunes enfants (au moins un enfant ag´ ˆ e de ,6 ans) et ceux ou` vivaient des enfants plus ag´ ˆ es (tous les enfants ag´ ˆ es de 6 a` 11 ans). R E´ S U L T A T S : Des 66 631 foyers inclus, l’ETS a` domicile concernait 25% des foyers sans enfants et 22% des foyers avec enfants. Les foyers avec enfants e´ taient un peu moins enclins a` eˆ tre expos´es a` l’ETS que les foyers avec enfants (OR 0,83 ; IC95% 0,80–0,87). Il existait une variation de l’ETS en fonction du niveau d’´education et de revenu. Par contre, il n’existait pas de variation en fonction de l’age ˆ des enfants (OR 0,98 ; IC95% 0,91–1,05). C O N C L U S I O N : Les foyers avec enfants sont moins enclins a` eˆ tre expos´es a` l’ETS, mais seulement de fa¸con marginale. RESUMEN
M A R C O D E R E F E R E N C I A : Los ninos ˜ que viven con un fumador se encuentran ma´s expuestos al humo del tabaco en el ambiente (ETS) que los ninos sin esta ˜ convivencia, aunque la persona evite fumar al interior del hogar. Dados los riesgos de esta exposicion ´ en la infancia, se planteo´ la hipotesis ´ de que es menos probable que exista una exposicion ´ al humo del tabaco en los hogares donde viven ninos ˜ que en los hogares sin ninos. ˜ M E´ T O D O : Se llevo ´ a cabo un ana´lisis transversal de la Encuesta de Salud Comunitaria del Canada´ en el 2009 y el 2010 con el fin de estudiar la asociacion ´ entre los ninos de edad de ,12 anos de los hogares y la ETS, ˜ ˜ mediante un modelo de regresion ´ log´ıstica; se definieron como factores de confusion ´ o modificadores del efecto la educacion ´ en el hogar y el ingreso. Se practico´ un ana´lisis
en subgrupos en el cual se compararon los hogares con ninos ˜ menores (como m´ınimo un nino ˜ de edad de ,6 anos) con los hogares con ninos mayores (solo ninos ˜ ˜ ˜ entre los 6 anos ˜ y los 11 anos ˜ de edad). R E S U L T A D O S : Se incluyeron 66 631 hogares en el ana´lisis; ocurrio´ el ETS en el 25% de los hogares sin ninos Fue menos ˜ y en el 22% de los hogares con ninos. ˜ probable que ocurriese esta exposicion ´ en los hogares con ninos ˜ (OR 0,83; IC95% 0,80–0,87). Se observo´ una modificacion ´ del efecto por la educacion ´ y los ingresos. No se observo´ diferencia del ETS entre los hogares con ninos ˜ menores y con ninos ˜ mayores (OR 0,98; IC95% 0,91–1,05). ´ N : La diferencia de la probabilidad del CONCLUSIO ETS en los hogares con ninos ˜ y los hogares donde no viven ninos ˜ es m´ınima.
