CME articleThe effects of tobacco smoke exposure on respiratory health in school-aged children
Section snippets
Passive exposure to environmental tobacco smoke
Exposure of children to ETS is a highly prevalent problem; evidence from large, multinational surveys provides estimates that 39–71% of children are currently exposed to ETS.5, 6, 7 These results are primarily based on parental reports of smoking habits and are therefore subject to underreporting bias, but they correspond reasonably well with data based on plasma cotinine measurements in the USA National Health and Nutrition Examination Survey (NHANES) III study,8 in which young children in the
Effects of tobacco smoke on asthma and asthma-like symptoms in children
One of the challenges of investigating the independent effects of tobacco smoke exposure in childhood on respiratory outcomes is to separate the persisting effects of exposure in utero and early infancy from the effects of current exposure. There is evidence of a strong and consistent relationship between maternal smoking during pregnancy and lung function decrements in infancy15, 16 and wheezing in early childhood.17, 18 There is also evidence that maternal smoking is associated with an
Effects of tobacco smoke exposure on lung function in children
The effects of tobacco smoke exposure on lung function in children are dependent on the source, timing and dose of exposure and may be modified by the sex of the child and the child's asthma status. There is evidence that both passive exposure at different developmental stages and active smoking during adolescence have detrimental effects on pulmonary function in cross-sectional studies and on the rate of growth of pulmonary function in longitudinal analyses.
In their series of systematic
Effects of tobacco smoke exposure on other respiratory problems in childhood
Passive exposure to ETS in childhood has been consistently associated with middle ear problems in early childhood.46 This association wanes during the school years, when the effects of ETS exposure on the upper airway include habitual snoring,47, 48 part of the spectrum of obstructive sleep apnoea. However, although sleep fragmentation in infants has been described in association with tobacco smoke exposure,49 this relationship is not well established in older children.
Smoke exposure has also
Possible mechanisms of tobacco smoke-related effects and genetic interactions
There are many potential pathways of tobacco smoke toxicity in the lungs, but, aside from mutagenesis, one of the primary common pathways is induction of inflammation. Oxidative stress is important in this regard, and there are a number of well-described antioxidant mechanisms available to the lungs to combat the effects of oxidative stress. In adults, deficiencies of alpha-1-antiproteases, notably alpha-1-antitrypsin, are associated with destruction of lung architecture in association with
Conclusion
There is strong evidence that exposure to tobacco smoke is harmful to children's respiratory health. The strength of association between ETS exposure and respiratory outcomes in school-aged children, evidence of dose–response effects and the replication of findings implies that there is likely to be a casual relationship in spite of the fact that much of the evidence stems from observational studies. The growing number of studies of ex vivo and in vivo interactions between, and the genetic
Research directions
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The long-term effects on pulmonary function and disease persistence of smoking during adolescence
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Effective, targeted interventions to prevent smoking in childhood and adolescence
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Gene–environment interactions to provide further evidence of casual associations, although avoidance of smoke exposure should target all children and not just those who are genetically susceptible
Key points
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The strongest associations with disease outcomes and pulmonary function deficits in school-aged children are with tobacco smoke exposure during pregnancy and infancy.
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Current tobacco smoke exposure in children is associated with increased respiratory symptoms, including worsening of asthma.
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Smoking in childhood and adolescence is associated with decrements in pulmonary function that may lead to chronic obstructive pulmonary disease in adulthood.
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Although effect estimates for the strength of
Educational aims
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To review the effects on the respiratory system of exposure to tobacco smoke in school-aged children.
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To discuss the relative contributions to respiratory symptoms, pulmonary function and disease of the respiratory system in children of tobacco smoke exposure during pregnancy and early infancy compared with later childhood exposure.
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To review the evidence for long-term adverse consequences of active smoking in children and adolescents.
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To consider possible mechanisms of the adverse effects of
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