4.13 Estimates of morbidity and mortality attributable to secondhand smoke

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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

As noted elsewhere in this Chapter, active smokers are at greater risk of disease or death due to smoking, than are non-smokers from exposure to secondhand smoke. However the amount of injury caused by secondhand smoke is not trivial. Estimates based on data from the USA73 and the UK74, 75 show that for every 10 deaths caused by smoking among smokers, one death occurs in a non-smoker due to exposure to secondhand smoke. Secondhand smoke is thought to be responsible for almost 3% of all deaths in the USA each year,22 and is regarded as the third leading preventable danger to health after active smoking and alcohol misuse in that country.21, 22

A small number of reports have published estimates of deaths caused by secondhand smoke in Australia over the past decade. Estimates vary depending on methodology used and disease entities included. Key findings from these reports are presented below.

4.13.1 Estimated mortality from secondhand smoke in Australia in 2004–05—the Department of Health and Ageing, 2007

Secondhand smoke caused the deaths of an estimated 141 Australians in 2004–05, according to the Commonwealth Department of Health and Ageing (DHA).[4]79 Of this total, 113 occurred in adults and 28 deaths occurred in babies (Table 4.3).[5]

About 90% of the deaths caused by secondhand smoke in adulthood were due to ischaemic heart disease. Most deaths caused by secondhand smoke occur later in life, reflecting the contribution of chronic lifelong exposure to the development of heart disease and lung cancer. There were more than twice as many deaths among adult women as there were among men. This reflects the historically higher rates of active smoking among men compared with women in previous decades.

These estimates are likely to be conservative, since they do not include deaths from all diseases now considered by some agencies to be caused by exposure to secondhand smoke. Additionally, the estimates for deaths from lung cancer caused by secondhand smoke are restricted to exposed non-smokers married to a smoker (so excluding non-smokers exposed in workplaces and other settings), and a cautious approach to quantifying deaths from ischaemic heart disease has been adopted compared with other methodologies (shown by the findings of the report prepared for The Cancer Council NSW—see Section 4.13.2).

The report for 2004–05 does not quantify morbidity (non-fatal illness) caused by secondhand smoke, but makes the comment that 'the overwhelming proportion of the morbidity attributable to involuntary smoking... is borne by the young.'p. 2379 In the previous report in the series, which publishes data for 1998, it was estimated that secondhand smoking caused close to 2000 hospital admissions in Australia in 1998. About three-quarters of these admissions occurred in children under the age of 14.40

4.13.2 Estimated deaths due to secondhand smoke in Australia in 1998—The Cancer Council NSW, 2004

Calculations of deaths in Australia caused by secondhand smoke have also been published in a report commissioned by The Cancer Council New South Wales. Main findings are summarised in Table 4.4.80 Based on scaling from US data based on relative population size, Repace estimated that in 1998, about 4200 adult non-smokers may have died in Australia from secondhand smoke.80 The estimates by Repace include a wider range of diseases that those considered in the AIHW reports discussed above, but exclude deaths in infancy. Repace makes the observation that even if only deaths from lung cancer and heart disease caused by secondhand smoke are considered, for which the greatest amount of scientific evidence exists, then the annual toll from secondhand smoke is still in the order of 3464 deaths.80

4.13.3 Estimated mortality and morbidity from secondhand smoke in Australia—the National Health and Medical Research Council, 1997

Estimates of mortality published by the National Health and Medical Research Council (NHMRC) in 1997 showed that 11 deaths from lung cancer and 77 deaths from a major coronary event could be attributable to secondhand smoke annually.16 The authors of this information paper commented that these estimates were likely to be very conservative, as they were restricted to never-smokers who had been exposed in the home environment, due to limitations in availability of more general Australian exposure data.

The NHMRC's Information Paper also estimated that secondhand smoke was a factor in causing asthma symptoms in 46,500 Australian children annually, and caused lower respiratory illness in 16,300 children. More than 5000 hospital separations in children every year could be attributed to secondhand smoke.16