In order to attain consistency for comparison, the authors used data from 2004 for their analysis, since this was the last year to have comprehensive data across the 192 countries studied. They estimated both deaths and years lost of life in good health (DALYs). Worldwide, 40% of children, 33% of male non-smokers, and 35% of female non-smokers were exposed to second-hand smoke in 2004. This exposure was estimated to have caused 379 000 deaths from ischaemic heart disease, 165 000 from lower respiratory infections, 36 900 from asthma, and 21 400 from lung cancer.
603 000 deaths were attributable to second-hand smoke in 2004, which was about 1% of worldwide mortality. 47% of deaths from second-hand smoke occurred in women, 28% in children, and 26% in men. The largest disease burdens were from lower respiratory infections in children younger than 5 years (5 939 000/54%), ischaemic heart disease in adults (2 836 000/26%), and asthma in adults (1 246 000/11%) and children (651 000/6%).
Worldwide, children are more heavily exposed to second-hand smoke than any other age-group, and they are not able to avoid the main source of exposure as it is mainly their close relatives who smoke at home. The authors of the current study note that smoke exposure in a home where somebody smokes appears similar across most regions, although more intense in Asia and the Middle East. Furthermore, children are the group that has the strongest evidence of harm attributable to second-hand smoke.
"Enforcing complete smoke-free laws could probably substantially reduce the number of deaths attributable to exposure to second-hand smoke within a few years of its implementation, with accompanying reduction in costs of illness in social and health systems", says Mattias Oberg, researcher at Institute of Environmental Medicine, Karolinska Institutet, and one of the study authors.
Oberg M, Jaakkola M, Woodward A, Peruga A, Pruss-Ustun A
Global burden of disease from secondhand smoke
The Lancet, Online First 26 November 2010
Source: Karolinska Institute