Previously, people often only considered second-hand smoke as a welfare issue, focusing on the smell and the irritation that tobacco smoke causes to eyes, nose and throat. But now the weight of evidence for much more serious risks to health from second-hand smoke has grown too great to ignore. Tobacco smoke contains around 4,000 chemicals, including arsenic, benzene, formaldehyde and ammonia. Around 60 of these chemicals are known or suspected to cause cancer. Many of the toxic chemicals are ...

Previously, people often only considered second-hand smoke as a welfare issue, focusing on the smell and the irritation that tobacco smoke causes to eyes, nose and throat. But now the weight of evidence for much more serious risks to health from second-hand smoke has grown too great to ignore.

Tobacco smoke contains around 4,000 chemicals, including arsenic, benzene, formaldehyde and ammonia. Around 60 of these chemicals are known or suspected to cause cancer. Many of the toxic chemicals are actually more concentrated in the smoke that’s given off by the burning tip of a cigarette (sidestream smoke). Around 85 per cent of the smoke in a room where people are smoking is the more toxic sidestream smoke. By breathing in it in the atmosphere, the non-smoker is exposed to many of the same health risks as the smoker.

The best known risk to smokers, lung cancer, is also more common in people regularly exposed to second-hand smoke. The Government’s Scientific Committee on Tobacco and Health (SCOTH) reported in 1998 that exposure to second-hand smoke increases the risk of lung cancer in non-smokers by 20-30 per cent.

Even though they inhale only 1% of the smoke, non-smokers exposed to second-hand smoke may suffer 25 per cent of the increased risk of heart disease associated with active smoking (one recent study suggests it might be as much as 50 per cent). Just 30 minutes of breathing second-hand smoke can reduce the coronary blood supply of a non-smoker to the same level as that of a smoker.

A study in New Zealand found that exposure to second-hand smoke increases the risk of stroke by 82 per cent in non-smokers. This is a serious concern, as stroke is such a common condition. Moreover, around 3.4 million people in the UK have asthma and for most of these, tobacco smoke is a trigger for an asthma attack. For someone with asthma, just one hour of exposure to second-hand smoke can cause a 20 per cent deterioration in lung function. During pregnancy, breathing in second-hand smoke increases the risk of having a baby with a low birth weight. Small babies are at much greater risk of infections and other health problems.

A recent review of international research on the immediate health impact of smoke-free workplace legislation found rapid and dramatic improvements. Air quality, respiratory health and levels of heart attacks and heart disease all improved substantially within months of the legislation being introduced.

There has been greater focus on the dangers of second-hand smoke since .