Twenty years after the first surgeon general's report on secondhand smoke, the evidence is now "indisputable" that the noxious fumes are a major health threat that kills an estimated 50,000 people each year, a new federal study said Tuesday.
There is no level of exposure to smoke that is safe, and the children of smokers are at special risk, Surgeon General Richard H. Carmona said in releasing the new report.
"I am here to say the debate is over, the science is clear," Carmona said during a televised news conference from Washington. "Secondhand smoke is not a mere annoyance. It is a serious health hazard."
Studies in the two decades since the first federal report confirm that secondhand smoke is linked not only to heart disease and lung cancer, but also to breast cancer, childhood cancer, nasal sinus cancer, ear infections and asthma. Recent results have also shown a clear link to sudden infant death syndrome.
The only way to combat the health threat, he said, was to follow the lead of California and 15 other states and ban all smoking in public buildings.
The report estimated that about 30% of indoor workers are not protected by smoke-free laws.
Carmona said parents should protect the health of their children by stepping outside their homes before lighting up.
"So many children are exposed in the home," said Thomas Glynn of the American Cancer Society. "If we do nothing else, we need to protect children because they are more vulnerable and the effects are lifetime effects."
For everyone else, Carmona said, the best advice is simply "stay away from smokers."
Among the report's major conclusions:
* Exposure of nonsmokers to tobacco smoke increases their risk of both heart disease and cancer by as much as 30%.
* Even a brief exposure to tobacco smoke can increase risk, especially for people with heart and respiratory diseases.
* Segregating smokers is not an effective technique for preventing exposure of nonsmokers, and even the best available technology does not cleanse the air adequately.
* There is no evidence that smoke-free laws have significantly reduced sales at bars and restaurants.
The number of smokers in the U.S. has declined sharply since the 1964 surgeon general's report linking smoking to health problems.
The report eventually led to warnings on cigarette packages, advertising restrictions and health education programs that have helped reduce the smoking prevalence rate among adults from 42.4% in 1965 to 20.9%, or 44.5 million people, in 2004, the Centers for Disease Control and Prevention has reported.
The drop in smoking has been accompanied by a decline in cancer rates, although until recently, that decline has been overwhelmed by the growth in population. But the American Cancer Society reported in February the first decline in the absolute number of cancer deaths since 1930. The decline was small -- a drop of only 369 out of about 557,000 in 2003 -- but the results were attributed in large part to the smoking decreases.
Between 1988 and 2002, the report said, the percentage of adult nonsmokers exposed to secondhand smoke has been halved to about 43%. That exposure was determined by measuring blood levels of a key nicotine byproduct called cotinine.
Even among those exposed, the median level of cotinine has dropped about 70%. About 20% of children have been exposed to secondhand smoke at home, and their cotinine levels are twice those in adults.
The report is simply a compilation of research conducted in the last two decades. Nonetheless, experts hope it will galvanize public sentiment in much the same way that the 1964 report on smoking and health did, accelerating the momentum toward an extension of smoke-free laws to cover nonsmokers who are now unprotected.