U.S. Surgeon General Richard H. Carmona today issued a comprehensive scientific report which concludes that there is no risk-free level of exposure to secondhand smoke. Nonsmokers 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. The finding is of major public health concern due to the fact that nearly half of all nonsmoking Americans are still regularly exposed to secondhand smoke.

The report, The Health Consequences of Involuntary Exposure to Tobacco Smoke, finds that even brief secondhand smoke exposure can cause immediate harm. The report says the only way to protect nonsmokers from the dangerous chemicals in secondhand smoke is to eliminate smoking indoors.

"The report is a crucial warning sign to nonsmokers and smokers alike," HHS Secretary Michael Leavitt said. "Smoking can sicken and kill, and even people who do not smoke can be harmed by smoke from those who do."

Secondhand smoke exposure can cause heart disease and lung cancer in nonsmoking adults and is a known cause of sudden infant death syndrome (SIDS), respiratory problems, ear infections, and asthma attacks in infants and children, the report finds.

"The health effects of secondhand smoke exposure are more pervasive than we previously thought," said Surgeon General Carmona, vice admiral of the U.S. Public Health Service. "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 nonsmoking adults." Secondhand smoke contains more than 50 cancer-causing chemicals, and is itself a known human carcinogen. Nonsmokers who are exposed to secondhand smoke inhale many of the same toxins as smokers. Even brief exposure to secondhand smoke has immediate adverse effects on the cardiovascular system and increases risk for heart disease and lung cancer, the report says. In addition, the report notes that because the bodies of infants and children are still developing, they are especially vulnerable to the poisons in secondhand smoke."

"The good news is that, unlike some public health hazards, secondhand smoke exposure is easily prevented," Surgeon General Carmona said. "Smoke-free indoor environments are proven, simple approaches that prevent exposure and harm." The report finds that even the most sophisticated ventilation systems cannot completely eliminate secondhand smoke exposure and that only smoke-free environments afford full protection.

Surgeon General Carmona noted that levels of cotinine — a biological marker for secondhand smoke exposure — measured in nonsmokers have fallen by 70 percent since the late 1980s, and the proportion of nonsmokers with detectable cotinine levels has been halved from 88 percent in 1988-91 to 43 percent in 2001-02.

"Our progress over the past 20 years in clearing the air of tobacco smoke is a major public health success story," Surgeon General Carmona said. "We have averted many thousands of cases of disease and early death and saved millions of dollars in health care costs." He emphasized, however, that sustained efforts are required to protect the more than 126 million Americans who continue to be regularly exposed to secondhand smoke in the home, at work, and in enclosed public spaces.

To help communicate the report findings as widely as possible, the Surgeon General unveiled an easy-to-read guide with practical information on the dangers of secondhand smoke and steps people can take to protect themselves.

Copies of The Health Consequences of Involuntary Exposure to Tobacco Smoke: A Report of the Surgeon General and related materials are available on the Surgeon General"s Web site.