4.12 Population prevalence of exposure to secondhand smoke in the home

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4.1 Background

4.2 What is secondhand smoke?

4.3 What is in secondhand smoke?

4.4 Cardiovascular disease and secondhand smoke

4.5 Lung cancer and secondhand smoke

4.6 Cancers of other sites

4.7 Health effects of secondhand smoke for infants and children

4.8 Effects of secondhand smoke on the respiratory system in adults

4.9 Secondhand smoke and pregnancy

4.10 Secondhand smoke and increased risk of infectious disease

4.11 Secondhand smoke and diabetes

4.12 Population prevalence of exposure to secondhand smoke in the home

4.13 Estimates of morbidity and mortality attributable to secondhand smoke

4.14 Public attitudes to secondhand smoke

Acknowledgments

References

The most recent data published on prevalence of exposure to secondhand smoke are presented in this section, with the various publications reporting on the findings of National Drug Strategy Household Survey of 2004 providing the basis for most of the following discussion. It should be noted that increased public awareness of the damage to health caused by secondhand smoke, especially since the progressive introduction of further legislation for smokefree workplaces and public places in most Australian states and territories, is likely to have continued to exert downward pressure on exposure in the home. Therefore the following information should be regarded cautiously, since it is likely to provide higher estimates than reflect practice subsequent to 2004.

Levels of exposures to secondhand smoke in other settings, including the workplace, in venues such as hotels, bars and restaurants, and other indoor and outdoor areas are discussed in Chapter 15.

Although most Australian non-smokers are not exposed to secondhand smoke in the home environment,63 for those individuals who do live with one or more smokers, the home is a major source of exposure to secondhand smoke.

Exposure to secondhand smoke in the home has declined since 1995, reflecting a continuing decline in the prevalence of smoking as well as an increase in smokers confining their smoking to outside the home environment (Table 4.1).64 Public awareness of health dangers of secondhand smoke has increased over time (see Section 4.14), and it is likely that increased regulation of smoking in the workplace and in public places over the past decade has also influenced attitudes to smoking in the home.65, 66

4.12.1 Exposure in infancy

A study undertaken in 1998–1999 in New South Wales which assessed infants' exposure to secondhand smoke, verified by biochemical testing for cotinine in the infants' urine, found that almost half (47%) of babies aged up to 12 months had detectable amounts of cotinine in their urine.67 The main locations in which parents reported that their children had been exposed to secondhand smoke were at a friend's or relative's house (22%), at a shopping centre (18%), in the home (10%), at a restaurant or hotel (8%), in an outdoor location (8%), and in the car (6%). Thirty-eight percent of the infants included in the study lived in a household with one or more smokers, but as noted above, only 10% of parents nominated the home environment as the main location for their child's exposure to secondhand smoke. Babies of smokers were 14 times more likely to show detectable levels of cotinine in their urine than babies of non-smokers. The authors of this study observed that parents who smoke may have thought that they were taking steps to protect their children from secondhand smoke, but that their measures appeared to be insufficient.67

4.12.2 Exposure in childhood

In 1995 almost one third of households in which children lived included someone who smoked inside the home, declining to about 12% in 2004 (Table 4.1).64 Smokers living in households that included children were less likely to smoke indoors than smokers in households with no dependent children. Despite the significant reduction in exposure over the past decade, an estimated 600,000 dependent children aged 14 or under were still being exposed to secondhand smoke in the home in 2004.64[1][2][3]

4.12.3 Exposure in non-smoking teenagers and adults

The National Drug Strategy Household Survey (2004) reports that most Australian non-smokers are not exposed to secondhand smoke inside the home.63 The likelihood of exposure declines with age, presumably reflecting the greater ability of an individual to control his or her own environment as they attain adulthood. Table 4.2 shows that in 2004, about one in six non-smoking adolescents aged 12-15 lived with one or more smokers who smoked in the home, and a further quarter of adolescents lived with at least one smoker who avoided smoking indoors. The vast majority of non-smoking adults aged 20 or older are not exposed to secondhand smoke in the home, with only 6% reporting that they lived in a house in which smoking occurred.

Apart from protecting the health of non-smoking adults and children, restrictions on smoking at home have also been shown to be associated with reduced smoking behaviour among adolescents.68, 69 See Chapter 5 for further discussion.

4.12.4 Levels of exposure to secondhand smoke in disadvantaged groups

As the relationship between socioeconomic disadvantage and increased prevalence of smoking is well-established—see Chapter 1, Section 1.7 —it is not surprising to find that members of disadvantaged groups are more likely to be exposed to secondhand smoke. Research from New South Wales shows that variables such as being younger, having a lower level of education, having no restrictions on smoking at work, and being of Aboriginal or Torres Strait Islander origin all correlate with a higher likelihood of living in a smoky environment.65

Disadvantaged children are particular risk. An analysis of NDSHS data from 2001 has shown that children of the most disadvantaged households are more than twice as likely to be exposed to secondhand smoke at home than children in the least disadvantaged circumstances (26% compared with 10%).70 A study from New South Wales has found that children from families of lower socioeconomic status, and children in single-parent families, are more likely to be exposed to secondhand smoke.67 Of greatest concern is the study involving Indigenous primary and high school-aged children in three remote Northern Territory communities that found that almost every child (98%) lived with at least one smoker, and 43% lived with five or more smokers.71

The continued high exposure of some disadvantaged groups to secondhand smoke contributes to their greater burden of ill-health.72