Passive smoking doubles the risk of acute respiratory illness in children, and if both mother and father smoke during the pregnancy, the baby is eight times more likely to die of cot death than if niether parent smoke.

But the poll for the Doctor Patient Partnership revealed that 23% of adults said they did not know that parental smoking could lead to childhood health problems.

One in 10 believed smoking would have no adverse effect on children's health and only 7% were aware of the link between smoking and cot death.

Less than half (41%) were aware that parental smoking could lead to children developing asthma.

The results of the poll were released at the launch of a DPP campaign to highlight the damage to children's health caused by parental smoking.

The DPP is an initiative set up by the British Medical Assoication and the Department of Health to provide the public with information about health issues and how to use the NHS appropriately.

Leaflets giving information about the effects of smoking on children and young babies are to be distributed through GP's surgeries and ante-natal clinics throughout the UK.

Callers to the national telephone advice line Quitline who have children will also be sent the booklet and the information will be included in the packs given to new mothers when they leave hospital.

Frightening results

Dr Simon Fradd was concerned by the survey results

Dr Simon Fradd, chairman of the DPP, said: "These results are frightening.

"They show that many people who smoke around their children are genuinely unaware of the extent of the problems they can cause to their children's health.

"The survey showed that 18% of respondents from the poll thought that if they smoked in another room there would be no effect on children in the house.

"This is simply not true. General practitioners have a responsibility to make sure parents are aware of the effect of smoking on themselves and their children."

The campaign is being run jointly by the DPP, the National Asthma Campaign and the Foundation for the Study of Infant deaths.

Asthma link

Smoking is linked to asthma

Dr Martyn Partridge, chief medical advisor for the National Asthma Campaign, said: "Smoking around children who already have asthma makes their symptoms far worse, while smoking during pregnancy increases the risk of the unborn child developing a wheeze in later life.

"Parents, and indeed all adults ought to know these stark facts about what they may be doing to others and themselves if they smoke."

Joyce Epstein, secretary-general of the Foundation for the Study of Infant Deaths, said: "Nine babies die every week from cot death in the UK, making it the major cause of death in babies over one month old, and it is shocking that hardly anybody is aware that we can cut cot death by cutting smoking.

"The message in this campaign is don't smoke anywhere near babies - it is simply not worth it."