Reports of smoking in cars with nonsmokers ranged from a low of 29% in Australia and the United Kingdom, to 34% in Canada, and to a high of 44% in the United States. The lower reports of smoking in cars with nonsmokers in Australia and the United Kingdom could be due to widespread comprehensive smoke-free laws in both countries, along with Australia’s long history of advocacy for banning smoking in cars with children and lower dependence on car use in the United Kingdom compared with the other three countries (as measured by use in large cities; Kenworthy & Laube, 1999
). The relatively higher reports of smoking in cars with nonsmokers in the United States could be due to higher car dependence and the United States’s lower frequency of comprehensive smoke-free laws—at the time of the survey, fewer than 50% of states were covered by comprehensive smoke-free laws, in contrast to nearly 100% of the three other countries (Kenworthy & Laube).
Across the four countries, men were more likely to smoke in cars with nonsmokers than women, replicating a finding from a study of smokers in the EU (European Commission, 2007
). It may be that women are more conscientious of exposing nonsmokers to cigarette smoke, particularly if the nonsmokers are children, or that men travel less in cars with children than women. Younger smokers were also more likely to smoke in cars with nonsmokers. The same EU study similarly found that younger smokers were more likely to smoke in cars with nonsmokers (European Commission). Young adults’ higher reports of smoking in cars with nonsmokers may be a result of more time spent in cars with a variety of peer group members, as opposed to family members and children. No relation was found between education and income and smoking in cars with nonsmokers. In contrast, an observational study in New Zealand found that smokers in cars in highly deprived areas were more likely to smoke in the presence of nonsmokers (Martin et al., 2006
). The finding that those with and without children are just as likely to smoke in cars with nonsmokers follows a study of 6,985 adults in the state of California that found that the presence of children in the home did not predict car smoking bans for smokers (Norman et al., 1999
Following our prediction, we found that heavier smokers with weaker intentions to quit were more likely to smoke in cars with nonsmokers, as were daily smokers. This finding is consistent with a study of smokers in the EU that showed that daily smokers and those who smoke more cigarettes per day are more likely to smoke in cars with nonsmokers, and a study of smokers in the United States that found that smokers who smoked 10 or more cigarettes/day were less likely to have car smoking restrictions (European Commission, 2007
; Kegler & Malcoe, 2002
For modifiable correlates, we found that smokers who did not believe cigarette smoke was dangerous and could cause lung cancer in nonsmokers were more likely to smoke in cars with nonsmokers. This is consistent with a previous study using the 2002 and 2003 waves of the ITC-4 Survey that showed that smokers who believe that cigarette smoke exposure is dangerous to nonsmokers are more likely to have smoke-free homes (Borland et al., 2006
). We also found that smokers who allowed smoking in their homes were more likely to smoke in cars with nonsmokers. This replicates a finding from an ITC-4 Survey 2002–2003 study (Borland et al.). Smokers who lived in jurisdictions without comprehensive smoke-free laws were also more likely to smoke in cars with nonsmokers across the four countries. However, when we looked within the United States, we found no significant effect of statewide comprehensive smoke-free laws. Our analyses were complicated by the fact that (a) some municipalities within provinces/states had their own comprehensive smoke-free laws, (b) presence/absence of comprehensive smoke-free laws was highly correlated with country of residence, and (c) states/provinces had laws in place for varying lengths of time (anywhere from at the outset of survey to more than 5 years before the survey), this weakens the strength of conclusions that can be drawn. Additionally, a 2007 longitudinal study conducted in Scotland found no changes in nonsmoking adults and children’s exposure to cigarette smoke in cars after the introduction of comprehensive smoke-free legislation (Akhtar et al., 2007
; Haw & Gruer, 2007
). However, the utility of comprehensive smoke-free legislation for promoting smoke-free cars should not be discounted; previous studies have linked comprehensive smoke-free legislation with the implementation of smoke-free homes, and our study found that smokers with smoke-free homes are less likely to smoke in cars with nonsmokers (Borland et al.). Additionally, as demonstrated here, the countries with the most widespread comprehensive smoke-free laws and tobacco control programs have the lowest reports of smoking in cars with nonsmokers. Thus, it may be that societal norms are more important than the presence of legislation. No effect of a law banning smoking in cars with children in South Australia was found on reports of smoking in cars with nonsmokers across the Australian states. This may be because we did not specifically ask about when in cars with children.
A possible further limitation of this study is that it relied on self-reports of smoking in cars with nonsmokers. However, studies that examined the validity of self-report as a measure of children’s exposure to tobacco smoke, a behavior that would seem even less socially desirable than smoking around nonsmokers, have found that self-reports are valid indictors of the actual level of smoking (Hovell, Zakarian, Wahlgren, Matt, & Emmons, 2000
). Significant predictors of smoking in cars with nonsmokers can only said to be correlational as this study used cross-sectional data. We also do not know how often the respondents traveled in cars; thus, some of the effects could be due to those who rarely or never travel in cars saying that they never smoke rather than those who travel a lot and refrain. We also did not ascertain whether respondents’ car smoking policies varied depending on whether they were the driver or a passenger or whether the nonsmoking passengers were adults or children.