Passive smoking is 'twice as dangerous as believed'

Passive smoking may be twice as dangerous to health as previously thought, researchers say today.

Passive smoking may be twice as dangerous to health as previously thought, researchers say today.

Non-smokers exposed to other people's smoke have a 50 to 60 per cent increased risk of heart disease compared with those who live and work in a smoke-free environment, according to a new study. Previous research had put the risk of heart disease caused by passive smoking at only 25 to 30 per cent higher.

The finding, described by the British Heart Foundation as "potentially pivotal", is published in the online version of the British Medical Journal. Today, representatives of the British Medical Association meeting in Llandudno are expected to back a call for the Government to follow the lead of the Irish by banning smoking in pubs, restaurants and other workplaces.

Most studies of passive smoking have examined the risks of living with someone who smokes. But these "partner studies" have failed to take account of the fact that, in addition to the time they spend at home, non-smokers are also exposed to secondhand smoke in offices and restaurants, in pubs and other public places.

Researchers from St George's Hospital Medical School in Tooting, south London, say that measuring the levels of cotinine in the blood, a by-product of nicotine, is a more accurate way of assessing exposure to passive smoking from all these sources.

In a study of 4,729 men from 18 British towns, they found higher cotinine levels were linked with at least a 50 per cent increased risk of heart disease. The men were followed for 20 years after cotinine levels were measured at the start.

The risks were highest in the early years and seemed to decline with time, possibly because smoking generally was falling, so that non-smokers were exposed to less second-hand smoke. The research also suggested that three out of four non-smokers had an increased risk of heart disease because of exposure to passive smoking from all sources.

Peter Whincup, professor of cardiovascular epidemiology at St George's, who led the research, said: "This study adds to the weight of evidence that passive smoking is harmful and strengthens the case for limiting exposure to passive smoking as much as we can."

In May, research published by Imperial College, London, suggested passive smoking may cause 700 premature deaths in the UK each year, three times more than are caused by industrial accidents.

The British Heart Foundation said that the findings were "disturbing" and the evidence "compelling". Tim Bowker, associate medical director, said: "The need for a ban on smoking in public places has never been better illustrated than by this potentially pivotal study. The Government should not delay any further from introducing legislation to protect smokers from this unnecessary risk."