Passive smoking kills and "even brief exposure to secondhand smoke can cause immediate harm", said a US Department Health and Human Services (HHS) statement released Tuesday.

Citing the US Surgeon General's latest report on the effects of passive smoking, the HHS said only a ban on smoking indoors can prevent exposure to dangerous chemicals.

US Surgeon-General Richard H Carmona's "comprehensive scientific report" documents the "serious and deadly health effects" of passive smoking and concludes that there is "no risk-free level of exposure to secondhand smoke".

"Non-smokers exposed to secondhand smoke at home or work increase their risk of developing heart disease by 25 to 30 percent and lung cancer by 20 to 30 percent," read the report entitled 'The Health Consequences of Involuntary Exposure to Tobacco Smoke'.

The report also found that secondhand smoke exposure can cause heart disease and lung cancer in non-smoking adults and is a known cause of sudden infant death syndrome (SIDS), respiratory problems, ear infections and asthma attacks in infants and young children.

Secondhand smoke, also known as environmental tobacco smoke, is a mixture of emission from the burning end of a cigarette and what is inhaled by smokers.

According to Carmona, the new report updates the last Surgeon General's report on the health effects of involuntary smoking released 20 years ago.

"The health effects of secondhand smoke exposure are more pervasive than we previously thought.

"The scientific evidence is now indisputable; secondhand smoke is not a mere annoyance. It is a serious health hazard that can lead to disease and premature death in children and non-smoking adults."

Restrict smoking

Restrictions on smoking, he said, work better for effective control to exposures compared to technical approaches involving air cleaning or a greater exchange of indoor with outdoor air.

According to him, the most sophisticated ventilation systems are unable to completely eliminate secondhand smoke and that only smoke-free environments afford full protection.

He also said that children, most vulnerable to poisons in secondhand smoke, continue to be exposed to it by smoking parents and others although adult exposures had declined due to restrictions at work and public places.

The report found biologic evidence of passive smoking in an estimated 60 percent or more than 126 million non-smokers Americans.

Carmona advised clinicians to routinely ask about passive smoking when dealing with susceptible groups or children coming in with pneumonia.

"Because of the high levels of exposure among young children, their exposure should be considered a significant paediatric issue.

"Those caring for sick relatives with heart disease should be advised not to smoke in the presence of that person."

Dire warning

The newest findings is reportedly based on "a far larger body of evidence than was available" in the 1986 report, which did not address cardiovascular disease then.

HHS secretary Michael Leavitt said the report was a "crucial warning sign to non-smokers and smokers alike".

"Smoking can sicken and kill, and even people who do not smoke can be harmed by smoke from those who do."

In recent years, the US courts have held cigarette companies responsible for smoking-related deaths and soaring medical/healthcare costs.

Centers for Disease Control and Prevention (CDC) director Dr Julie Louise Gerberding, in the new report's foreword, said secondhand smoke has been a major cause of heart disease and lung cancer in healthy non-smokers.

She said although the research showed that smoke-free policies were "not the most economic and effective approach" for protecting non-smokers, they did provide the "greatest health impact".

"Separating smokers and non-smokers in the same airspace is not effective," she said, adding that separately-ventilated areas provided no protection.

The CDC's general estimate is that one in every five deaths in the US is smoking-related and that tobacco use account for more than USD75 billion a year in medical costs.