CENTERS FOR DISEASE CONTROL AND PREVENTION
Volume 14 • Number 3 • Fall 2001

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Clean Indoor Air: Critical Component of Comprehensive Tobacco Control

Smoke from burning cigarettes, pipes, and cigars and smoke exhaled by smokers has several names—second-hand smoke, passive smoke, environmental tobacco smoke. No matter what it's called, however, one thing is clear: it can kill nonsmokers who inhale it. 

"Every year as many as 3,000 nonsmokers die of lung cancer and at least 35,000 nonsmokers die of heart disease caused by inhaling secondhand tobacco smoke," said Beverly Kingsley, MD, epidemiologist with CDC's Office on Smoking and Health (OSH). 

Conclusive Evidence that Tobacco Smoke Is Harmful 
In the late 1970s and early 1980s, scientific research began to suggest that exposure to tobacco smoke had ill effects on nonsmokers' health. In 1986, The Health Consequences of Involuntary Smoking: A Report of the Surgeon General was published. It concluded that secondhand smoke causes lung cancer and that the children of smoking parents have more respiratory infections than the children of nonsmokers. 

Also in 1986, another report—this one by the National Research Council—reached the same conclusions. At that time, however, there was also the suggestion that secondhand smoke might be associated with heart disease. 

"The evidence continued to mount," said Dr. Kingsley. "In 1992, the Environmental Protection Agency [EPA] was able to classify secondhand tobacco smoke as a Group A carcinogen. Those carcinogens are known to cause cancer in humans. Other examples are asbestos and benzene." 

Also by 1992, enough evidence had been produced to show that second-hand smoke caused heart disease, and the American Heart Association declared that secondhand smoke is a major cause of preventable heart disease.

In 1997, the California Environmental Protection Agency extensively reviewed the scientific research to date on secondhand smoke. Studies conducted between 1992 and 1997 contributed greatly to the weight of evidence. The results from these studies showed that a causal relationship indeed existed between secondhand smoke and lung cancer, as well as between secondhand smoke and heart disease. 

In 2001, the Surgeon General's report (SGR) Women and Smoking came to the same conclusion, that exposure to secondhand smoke is a cause of lung cancer and coronary heart disease among women who are lifetime nonsmokers. Similarly, the SGR also recognized the health risks to infants posed by exposure to secondhand smoke during pregnancy. 

"For children, the effects of breathing secondhand smoke are particularly disturbing," said Dr. Kingsley. "Every year, more than 10,000 infants of smoking mothers are born with lower than normal birth weight. About 2,000 cases of sudden infant death syndrome are directly caused by exposure to tobacco smoke. From 7,500 to 15,000 infants and toddlers are hospitalized with bronchitis or pneumonia because they breathe tobacco smoke, and well over 100 of them die. Older children— more than a million of them—get middle ear infections, asthma, or bronchitis. And those figures are repeated year after year." 

According to 1996 data from the Current Population Survey and CDC's Behavioral Risk Factor Surveillance System, one-third to one-half of adults who smoke have children living with them, and 70% or more allow smoking in the home. The estimated number of children exposed at home to second-hand tobacco smoke ranges from 32,105 in Delaware to 1,120,051 in New York. 

"CDC estimated that in 1996, more than 15 million children and adoles-cents nationwide were exposed to secondhand tobacco smoke in their homes," said Dr. Kingsley. 

How Dangerous Is Secondhand Tobacco Smoke? 
"Secondhand smoke contains thousands of chemicals, and more than 50 of them cause cancer," said Patricia Richter, PhD, toxicologist with OSH. "Examples are benzene, benzo[a]pyrene, nitrosamine compounds, vinyl chloride, and polonium-210. Some chemicals, such as hydrogen cyanide and sulfur dioxide, are irritants or systemic toxicants—they cause respiratory diseases. Others are reproductive toxicants—that is, they cause health problems for unborn babies. Examples of those are nicotine and carbon monoxide. Nicotine also increases heart rate and blood pressure, and it's implicated in cardiovascular damage along with carbon monoxide." 

A new study just published in JAMA [the Journal of the American Medical Association] (2001;286:436-63) shows that after just 30 minutes of exposure, secondhand smoke had "abruptly reduced the CFVR" [coronary flow velocity reserve] of nonsmokers. "This provides direct evidence of a harmful effect of passive smoking on the coronary circulation of nonsmokers," the researchers said. 

"Let me give you an analogy to help make the risks of secondhand smoke clearer," said Terry Pechacek, PhD, Associate Director for Science at OSH. "How would you react if someone entered a restaurant or public place with a spray bottle filled with a brown liquid said to contain a dilute solution of 50 known carcinogens and asked if he or she could just spray some around the room? Chemically there is no difference between that request and someone asking to smoke indoors." 

CDC Shares Science to Support Clean Indoor Air 
CDC supports the states' clean indoor air programs in several ways. Through its National Tobacco Control Program (NTCP), CDC gives funds—$1 million to each state and somewhat less to each territory—for tobacco control programs. 

"We also give the states resource materials such as research findings and Surgeon General reports," said Monica Eischen, CDC program consultant. "And we translate the research findings into information that the local people can use when they discuss secondhand smoke with those with the authority to enact legislation or pass ordinances." 

"We also act as a clearinghouse of information about what's going on in each state," said Ms. Eischen. "We help state programs keep up-to-date on what's going on around the country related to clean indoor air." 

Besides giving money to the states, CDC also gives money to the National Association of Local Boards of Health and to the National Association of County and City Health Organizations to work on clean indoor air issues. 

"We also work with lots of nonprofit organizations, such as the American Cancer Society, American Lung Association, and American Heart Association." said Ms. Eischen. "In fact, we would be ineffective without them. They are our partners. We also partner with groups that work solely on tobacco issues, for example, Smokeless States, the Campaign for Tobacco-Free Kids, and the Americans for Nonsmokers' Rights Foundation." 

CDC's National Tobacco Control Program 
The NTCP has four goals, one of which is to eliminate nonsmokers' exposure to secondhand tobacco smoke. 

"Of course, the other three goals would, if achieved, also eliminate exposure to secondhand smoke," said Ms. Eischen. "They are all aimed at getting people to stop smoking or not to start smoking. Clearly, if no one smoked, there would be no exposure. In addition, reducing the number of people who smoke also makes smoking less socially acceptable." 

"That's the Achilles' heel for the tobacco companies—social acceptability," said Stanton Glantz, MD, School of Medicine, University of California at San Francisco. "If smoking is not socially acceptable, then the amount of tobacco that people buy will go down." 

Tobacco Industry's Position 
Experiences from the states and evidence from the tobacco companies' own internal documents show that the industry uses several key strategies to counter effective clean indoor air measures. 

One strategy is to work for weak statewide laws that preempt the authority of local communities to pass stricter ordinances—for example, a state law that restricts smoking in restaurants but not in bars or taverns, and that preempts counties, cities, and towns from restricting smoking in those venues. According to Tim Filler, Associate Director of Americans for Nonsmokers' Rights, 18 states (as of September 2001) have laws with such preemption provisions. 

Another strategy that tobacco companies use is to persuade the hospitality industry (primarily restaurants and bars) to oppose local clean air ordinances on the grounds that they will lose business if customers cannot smoke. 

"The argument that bars and restaurants lose business if their customers can't smoke doesn't hold up on examination," said Dr. Kingsley. "Studies published in top-quality medical journals like JAMA and conducted in more than 20 cities around the country show that sales are not reduced. In fact, in California, sales actually went up slightly after the ban on smoking in restaurants went into effect." 

"The health of the bartenders also got better," said James Repace, a former EPA senior science policy analyst and now a private consultant on second-hand smoke. "Just one month after smoking was banned in all bars in California, a study of 53 bartenders showed that their pulmonary function improved by 5% to 7%." 

One other tobacco industry strategy is to promote the "accommodation" of smokers and nonsmokers indoors through the establishment of nonsmoking sections or through ventilation or air cleaning systems.

The scientific evidence, however, does not support the effectiveness of either approach. The 1986 Surgeon General's report concluded that "the simple separation of smokers from nonsmokers within the same airspace may reduce, but cannot eliminate, the exposure of nonsmokers to secondhand smoke." And, according to Mr. Repace, "In 1994, OSHA [the Occupational Safety and Health Administration] stated that the carcinogenicity of secondhand smoke discounts the use of general ventilation as an engineering control for this contaminant. In other words, general ventilation doesn't work." 

"In fact, if we want ventilation to eliminate secondhand smoke," continued Mr. Repace, "we'd need tornado-like levels of air flow, which obviously is impractical." 

The Public Health Solution: Smoke-Free Environments 
The 2000 SGR Reducing Tobacco Use added to the considerable scientific evidence that smoke-free environments are the most effective method for reducing ETS exposure. Five separate Healthy People 2010 objectives focus on this issue and seek optimal protection of nonsmokers through policies, regulations, and laws requiring smoke-free environments in all schools, work sites, and public places. 

And now there's new evidence that the amount of tobacco smoke to which nonsmokers in the United States are exposed is going down, which is a good indication that restricting smoking in public places is having the desired effect. After nicotine enters the body of smokers or nonsmokers, it breaks down into several components, a major one being cotinine. The amount of cotinine in a person's blood indicates the amount of tobacco smoke that person has been exposed to. To determine the extent of nonsmokers' exposure to secondhand smoke, CDC measured cotinine in nonsmokers aged 3 years and older in the U.S. population during 1988–1991 and again in 1999, using blood samples from the National Health and Nutrition Examination Survey. 

"One significant finding was the more than 75% decrease in serum cotinine levels for nonsmokers in the United States," said Jim Pirkle, MD, PhD, of CDC's Environmental Laboratory and coauthor of the National Report on Human Exposure to Environmental Chemicals. 

Despite this dramatic decrease in people's exposure to tobacco smoke, Dr. Pirkle cautions against letting up on public health efforts to eliminate secondhand smoke from the environment. "Secondhand tobacco smoke remains a major public health concern, since more than half of American young people continue to be exposed to this known human carcinogen."

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This page last reviewed August 10, 2004

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