pakistan tobacco company - Second-hand smoke

The World Health Organisation, the United States Surgeon General and other public health bodies have concluded that exposure to environmental tobacco smoke (ETS), sometimes called ‘second-hand smoke’, is a cause of various serious diseases, including lung cancer, heart disease and respiratory illnesses in children.

They conclude that there is no known safe level of ETS exposure and hence advise that public health policy would be best served by bans on public smoking.

Our views of the science

The risks associated with ETS have been measured in epidemiological studies. These mainly use questionnaires to compare the incidence of diseases such as lung cancer in non-smoking women whose husbands were smokers, with non-smoking women whose husbands were non-smokers.

For lung cancer, the major studies report that relative risk associated with prolonged non-smoker exposure to ETS is 1.3. A relative risk of 1 means no risk, and prolonged active smoking is typically associated with a relative risk of lung cancer of the order of 20 or higher.

For heart disease, the major studies also report a relative risk for ETS exposure of around 1.3. The relative risk for active smoking and heart disease is typically of the order of 3 to 5.

Many epidemiologists say that relative risks below 2 are weak associations and are more difficult to quantify than stronger associations. Perhaps because the relative risks reported in individual studies tend to be below 2, many studies do not reach statistical significance.

Studies of respiratory illnesses in children whose parents smoke, and research into whether ETS exposure exacerbates symptoms for people with conditions such as asthma, suggest that ETS can increase risks of respiratory illnesses in children and can affect people with pre-existing conditions such as asthma.

Page last updated: 07/05/2010 16:49:39 GMT