Globally in 2016, an estimated one-fifth of males and one-third of females were exposed to secondhand smoke. Secondhand smoke exposure is highest in eastern Asia and Oceania and higher among women and children compared with men. In 2016, 884,000 deaths were attributable to secondhand smoke, of which 56,340 occurred among children under the age of ten. The distribution of years of healthy life lost due to illness, disability, or early death (disability-adjusted life-years, or DALYs) because of secondhand smoke peak during infancy and again in older age. 1
In 2016, diseases with the greatest DALY burden attributable to secondhand smoke were lower respiratory infections (6.4 million years), chronic obstructive pulmonary disease (2.5 million years), and middle ear infection (more than 200,000 years). Despite this substantial burden, exposure to secondhand smoke has been declining over time, likely due to the increased adoption of tobacco control measures in many countries since the implementation of the Framework Convention on Tobacco Control (FCTC). 1
There is very limited information regarding morbidity and mortality attributable to secondhand smoke in Australia. A small number of reports have published estimates of deaths caused by secondhand smoke, however these vary dramatically due to differences in methodology and diseases included in analysis. Findings from these studies are summarised below.
4.7.1 Estimated mortality and morbidity from secondhand smoke in Australia, 2017—the Global Burden of Disease Study
The Global Burden of Disease study estimates levels and trends in exposure, attributable deaths, and attributable disability-adjusted life-years (DALYs), by age group, sex, year, and location for 84 behavioural, environmental and occupational, and metabolic risks factors. It estimated that in Australia in 2017, 1,714 deaths and 43,102 years of healthy life lost (disability-adjusted life-years, or DALYs) were attributable to secondhand smoke. Three of the deaths were among infants under age one. 2
Among infants, deaths and DALYs attributable to secondhand smoke were caused by respiratory infections, while among all ages, additional leading causes included diabetes, cancer, cardiovascular disease, and chronic respiratory disease (Table 4.7.1). 2
4.7.2 Estimated mortality from secondhand smoke in Australia in 2004–05
The Department of Health and Ageing estimated that 141 Australians died from secondhand smoke in 2004–05. 3 Of these, 113 deaths occurred in adults and 28 deaths occurred in babies (Table 4.7.2).
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 reflecting the historically higher rates of non-smoking among women in previous decades.
These estimates are likely to be very conservative, since they do not include deaths from all of the diseases now understood to be associated with secondhand smoke exposure. Additionally, the estimates for deaths from lung cancer caused by secondhand smoke are restricted to exposed non-smokers married to a smoker and therefore exclude non-smokers exposed to secondhand smoke in workplaces and other settings). Finally, a cautious approach to quantifying deaths from ischaemic heart disease was adopted compared with the methods used in studies below.
While this report does not quantify morbidity (non-fatal illness) caused by secondhand smoke, the report states that ‘the overwhelming proportion of the morbidity attributable to involuntary smoking ... is borne by the young’. 3 In a previous report, it was estimated that secondhand smoking caused close to 2000 hospital admissions in Australia in 1998. About three-quarters of these admissions were estimated to have occurred in children under the age of 14. 4
4.7.3 Estimated mortality from secondhand smoke in Australia in 1998—Cancer Council New South Wales, 2004
In a study published by the Cancer Council NSW, US data was extrapolated to the Australian population to estimate the number of deaths attributable to secondhand smoke. 5 This study estimated that in 1998 4200 adult non-smokers died in Australia from secondhand smoke. These estimates are based on deaths from a a wider range of diseases than those considered in the Department of Health and Ageing reports discussed above, but exclude deaths in infancy and childhood. The Cancer Council NSW report notes that even if only deaths from lung cancer and heart disease caused by secondhand smoke are considered the annual toll from secondhand smoke is still over 3400 deaths. 5
4.7.4 Estimated mortality and morbidity from secondhand smoke in Australia—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 cardiovascular event could be attributable to secondhand smoke annually. 6 The authors acknowledged that these estimates are likely to be very conservative because they are restricted to never smokers who had been exposed to secondhand smoke in their home, due to limitations in the availability of more general Australian exposure data.
The NHMRC information paper also explored morbidity and estimated that secondhand smoke was a factor in causing asthma symptoms in 46,500 Australian children annually, and causing lower respiratory illness in 16,300 children. More than 5000 hospital separations in children every year were estimated to be attributable to secondhand smoke. 6
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References
1. Gakidou E, Afshin A, Abajobir AA, Abate KH, Abbafati C, et al. Global, regional, and national comparative risk assessment of 84 behavioural, environmental and occupational, and metabolic risks or clusters of risks, 1990–2016: A systematic analysis for the global burden of disease study 2016. The Lancet, 2017; 390(10100):1345-422. Available from: https://doi.org/10.1016/S0140-6736(17)32366-8
2. Global Burden of Disease Collaborative Network. Global burden of disease study 2017 (GBD 2017) results. Seattle, United States Institute for Health Metrics and Evaluation (IHME), 2018. Available from: http://ghdx.healthdata.org/gbd-results-tool.
3. Collins D and Lapsley H. The costs of tobacco, alcohol and illicit drug abuse to Australian society in 2004–05. Canberra: Department of Health and Ageing, 2008. Available from: https://nadk.flinders.edu.au/files/3013/8551/1279/Collins__Lapsley_Report.pdf
4. Ridolfo B and Stevenson C. Quantification of drug-caused mortality and morbidity in Australia, 1998. Drug statistics series no. 7, AIHW cat. no. PHE-29.Canberra: Australian Institute of Health and Welfare, 2001. Available from: http://www.aihw.gov.au/publications/phe/qdcmma98/ .
5. Repace J. Estimated mortality from secondhand smoke among club, pub, tavern and bar workers in New South Wales, Australia. A report commissioned by the cancer council New South Wales. Woolloomooloo, Australia: The Cancer Council New South Wales, 2004. Available from: http://www.cancercouncil.com.au/editorial.asp?pageid=1020.
6. National Health and Medical Research Council. The health effects of passive smoking: A scientific information paper. Canberra: Australian Government Publishing Service, 1997.