Smoking in cars in England: a study of school students in an English city

Smoking is a major cause of preventable death in England, leading to more than 80,000 deaths a year (2009 data) [1]. Along with the direct harmful effects of smoking, exposure to secondhand smoke (SHS) is a significant cause of morbidity and mortality both among adults and children. In children, exposure to secondhand smoke is associated with an increased risk of sudden infant death, lower respiratory tract infections, middle-ear disease, and exacerbation of asthma [2]. It has been reported that the risk of adverse health effects for children increases with the number of smokers in the household [2], and that exposure occurs in particular in the home and the family car [3]. It has also been reported that for children exposed to smoking in cars there is a higher risk of developing respiratory symptoms [4].

Although smoking restrictions in various public places have been introduced, smoking while driving is still common and often occurs in the presence of adult non-smokers and children. Typically, smoke free rules in a car are more common among non-smokers than smokers [5], for example, in the Netherlands 36% of smokers allow smoking in cars carrying children [6]. In the UK, nearly a third of smokers smoke in their car when non-smokers are present [7]. However, in some countries, including Australia and some parts of Canada, legislation has been implemented to prohibit smoking in cars when children are present to protect them from exposure to tobacco smoke. Although in the UK smoking is restricted in vehicles used for work, smoking in private cars is not restricted even when children are present [8].

Although findings from earlier studies suggest that a considerable proportion of smokers smoke in their cars, there is limited up to date evidence on the extent to which children are protected from SHS in cars in England and what factors are associated with smoke free rules in cars. This study has therefore estimated the proportion of children from a large city in England travelling in cars where smoking is allowed, and identified factors associated with smoking being allowed in family car and frequency of travelling in cars where smoking is allowed, and with ever smoking among participants.

Out of 4,302 questionnaires received, 205 were from students who reported that their family does not have a car; 79 provided no data on either of the two questions on smoking in cars; 33 did not answer the question on whether smoking is allowed in their family car; and 31 did not report how often they travel in a car where smoking is allowed. Our findings suggest that there was a statistically significant difference in the frequency of traveling in a car where smoking was allowed in relation to smoking rules in a family car (Chi square 936.94, p < 0.001). While 73.6% of children from families where smoking in a car was not permitted never travelled in a car where smoking was allowed, only 4.1% of children with no rules banning smoking in a family car never travelled in a car where smoking was allowed and the majority of them (95.9%) at least sometimes travelled in a car where smoking was allowed. There were almost equal proportions of boys and girls in our sample including children from school years 7–11 (aged 11–16). For the majority of children, family members (parents, siblings) were non-smokers and smoking was not allowed in the family home. However, for more than 40% of children at least one of their friends was a smoker (Table 1 & Table 2).

The results from this study of a sample of English schoolchildren demonstrate that absence of smoke- free rules in family cars or other cars carrying children is still relatively common, and strongly related to social disadvantage. To our knowledge this is the first large study in England in recent years investigating rules regarding smoking in family and other cars in relation to a range of socio-economic and demographic variables, and smoking in their immediate social environment. Considering the effects of passive smoking on children’s health [3], smoking rules in family cars and potential exposure to secondhand smoke is an important public health issue.

Our study had some limitations. Due to the nature of the questions asked our measures of smoking in cars do not necessarily mean that in all cases respondents are exposed to tobacco smoke. However it is likely that exposure and frequency of travelling in a car where smoking is allowed and rules in the family car will be related. Also, although we had a sample of schools that are likely to be representative to Nottinghamshire, generalizability of the results to the rest of England and other parts of the United Kingdom might be questioned.

According to the national survey in 2011 25% of children aged 11–15 in England were ever smokers [14] while in our study, prevalence of ever smoking among children aged 11–16 was lower, at 21%. Similarly, our figures suggesting that nearly 15% of children were travelling in a car where smoking was allowed at least on some days are consistent with a finding from the national survey that 19% were often near people smoking in cars [14] and findings from the UK Youth Tobacco Policy Survey suggesting that 17% of 11–16 year old adolescent are exposed to smoking in cars more than once a week [15].

Although the findings from our analyses of associations between smoking in car rules and other determinants are of limited causal inference as a result of the cross-sectional study design, the associations with family and sibling smoking, deprivation [16] and lack of smoking rules in the home [17], indicate that smoking being allowed in cars was most common among children from families in which smoking is the norm. Recent estimates from 2012 national survey in England suggest that children from more deprived backgrounds are more likely to be exposed to smoking in cars [18]. The substantial discrepancies observed between the proportion of children with smoking allowed in the family car, and the proportion travelling in a car where smoking is allowed at least sometimes, highlight the importance of SHS in the cars of friends or relatives as a source of exposure in children, and therefore that preventing exposure will require policies covering all cars. It is also apparent from our findings that travelling in cars where smoking is allowed at least sometimes, and having no restrictions on smoking in the family car, were both associated with ever having smoked. Although based on cross-sectional data, these findings are consistent with previously reported evidence that exposure to smoking in cars is related to current smoking and smoking initiation among adolescents [19], and provide further support for comprehensive policies to prevent all forms of exposure.

Our findings are also in line with observation from other studies. In a repeated cross sectional study in New Zealand a slightly greater proportion of children (23%) have been reported to be exposed to smoking in cars in the previous week, however over time a slow decline of the proportion exposed has been observed [20]. Similarly, decline in exposure to smoking in cars over time has been observed among children in the United States [21, 22]. In New Zealand greater exposure to secondhand smoke was observed among children from lower socio-economic groups, and smoking being common in family and among friends, and being exposed to smoking at home or in a car was related to increased susceptibility to smoking and risk of becoming a smoker [20].

Apart from the serious health effects caused by smoking in the car on both smokers and non-smokers, one study has shown that smoking while driving is also associated with safety issues as smoking in the car distracts the driver, which leads to an increased risk of motor vehicle accidents among smokers [23]. This, together with the high level of public support for smoke-free car policies, including among children [15, 24, 25], and our results indicating the high prevalence of children unprotected by smoke-free car rules, particularly among more disadvantaged children and the potential influence on smoking uptake suggests that smoking in cars should be restricted.