Passive smoking claims more than 600,000 lives each year around the world - an estimated 1 per cent of all deaths, a study by the Word Health Organistation (WHO) has found.
Children are the group most heavily exposed to second-hand tobacco smoke, and around 165,000 of them die as a result, said researchers.
The study is the first to assess the global impact of inhaling other people’s smoke.
Based on 2004 data, the figures show smoking in that year killed almost six million people, either actively or passively by claiming the lives of non-smokers.
Second-hand smoke was believed to have caused 379,000 deaths from heart disease, 165,000 from respiratory infections, 36,900 from asthma and 21,400 from lung cancer.
In addition 10.9 million years of disability-free life were lost globally because of passive smoking.
The findings are published today in an early online edition of
the Lancet medical journal.
Dr Annette Pruss-Ustun, from the WHO in Geneva, Switzerland, and her fellow authors wrote: “Exposure to second-hand smoke is still one of the most common indoor pollutants worldwide.
“On the basis of the proportions of second-hand smoke exposure, as many as 40 per cent of children, 35 per cent of women and 33 per cent of men are regularly exposed to second-hand smoke indoors.
“We have estimated that second-hand smoke caused 603,000 deaths.. worldwide in 2004, corresponding to 1 per cent of all deaths.
“These deaths should be added to the estimated 5.1 million deaths attributable to active smoking to obtain the full effect of both passive and active smoking. Smoking, therefore, was responsible for more than 5.7 million deaths every year in 2004.”
The figures were obtained by analysing data from disease incidence studies and smoking surveys. They showed that chest infections in children younger than five, heart disease in adults and asthma in both adults and children represented the biggest health impacts from passive smoking.
The vast majority of deaths among children occurred in poor and middle-income countries, while in richer nations the proportion of adult casualties was higher.
In Africa, an estimated 43,375 children but only 9,514 adults were killed by inhaling second-hand smoke. This compared with 71 child deaths and 35,388 deaths among adults in the high-income countries of Europe.
“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 - mainly their close relatives who smoke at home,” the researchers wrote.
“Furthermore, children are the group that has the strongest evidence of harm attributable to second-hand smoke. These two factors should form the basis of public health messages and advice to policy makers.”
Overall disease burden was measured by means of disability-adjusted life years (Dalys), which show the number of “healthy” years lost due to premature death, illness and disability.
In 2004, passive smoking accounted for an estimated 10.9 million Dalys, or 0.7 per cent of the total worldwide disease burden. Almost two thirds of all deaths due to passive smoking, and a quarter of Dalys, were said to result from heart disease in adult non-smokers.
Smoking bans in the workplace greatly reduced the number of coronary events such as heart attacks, said the authors.
They added: “Policy makers should bear in mind that enforcing complete smoke-free laws will probably substantially reduce the number of deaths attributable to exposure to second-hand smoke within the first year of its implementation, with accompanying reduction in costs of illness in social and health systems.”
However, only 7.4 per cent of the world’s population lived in jurisdictions with comprehensive smoke-free laws. Where bans were in place, research had shown they reduced exposure to second-hand smoke in high-risk settings such as bars and restaurants by 90 per cent.
Educational strategies were needed to minimise exposure to second-hand smoke in the home, said the researchers.
The WHO study collected data from 192 countries.
Chairman of Ash Ireland Dr Brian Maurer said the research confirmed the “immensely harmful” effects of passive smoke.
“Passive smoke kills people on a vast scale - and this current study shows that children are especially affected.”
He said the Government must protect children and non-smokers from passive smoke and called for the introduction of a smoking ban in cars transporting children under the age of 16.
“I would ask those interests who still try to claim that passive smoke is harmless, to listen more to the WHO and less to their profit driven instincts,” Dr Maurer added.
Welcoming the study Irish Cancer Society spokeswoman Jane Curtin said exposure to second-hand smoke increases the risk of lung cancer by 20-30 per cent, heart disease by 25-30 per cent and stroke by 82 per cent.
Ms Curtin said: “Every year in Ireland 6,000 people die in Ireland as a direct result of both passive and active smoking.
“Tobacco kills more people in Ireland than road accidents, suicides, drugs, farm accidents and AIDS put together.”
She said smoking and exposure to second hand smoke is the single biggest cause of preventable deaths in Ireland and “must be tackled”.
