Fuel for smoking bans

Calls for a ban on smoking in public have been given further momentum this week by a new study highlighting the dangers of passive smoking. Researchers from New Zealand have used data from two national censuses to examine life expectancy in non-smokers and found that those living with a smoker die significantly earlier than those from smoke-free households.

Cigarette smoke contains more than 4,000 different chemicals, and it takes around two hours for the toxins from just one cigarette to clear a well-ventilated average-sized room. Few dispute the fact that living, working or socialising in a smoky environment is unpleasant - even for some smokers - but, up until recently, the evidence that passive smoking causes significant harm has been patchy.

Interest historically has focused on links between passive smoking and lung cancer but the evidence hasn't been that convincing. At worst, regular exposure to second-hand smoke increases your risk of developing lung cancer by around 20 per cent. That may sound a lot but lung cancer is so unusual in non-smokers that the increase isn't that significant in terms of absolute numbers - something the tobacco industry has been all too quick to point out. Fortunately investigators are now casting their net wider.

Japanese researchers have discovered that just 30 minutes' exposure to secondhand smoke at home, at work, in the pub or at a dinner party can damage the lining of the blood vessels supplying the heart. Which explains Greek research published last year that showed that lifetime-non-smokers who spent more than 30 minutes inhaling other people's smoke every day were nearly 50 per cent more likely to have a heart attack than their peers who lived, worked and socialised in a smoke-free environment.

But the most compelling data relates to the effects on children. Babies born to parents who smoke may be more at risk of developing childhood cancers such as leukaemia, and are much more likely to succumb to cot death and suffer from chest problems such as asthma (experts estimate that passive smoking causes 650 new cases every year in London alone). And it can even affect their teeth - chemicals in the smoke damage tooth enamel and smoking can double the odds of your child needing fillings.

The British Medical Association believes that passive smoking kills 1,000 people a year across the UK, while the anti-smoking charity Action on Smoking and Health (ASH) puts the figure closer to 13,000. The real figure almost certainly lies somewhere between the two, but since it took us half a century to prove that smoking was bad for smokers (doctors used to recommend it for people with asthma!) it is not surprising that it is taking time to quantify the risk from passive smoking.

For more information on the dangers of passive smoking check out the ASH website at www.ash.org.uk