Tobacco—What it Is and What it Does - Secondhand Smoke

Secondhand smoke, also known as environmental tobacco smoke (ETS) or passive smoke, is a health hazard for nonsmokers who live or work with smokers. The American Lung Association describes secondhand smoke as "a mixture of the smoke given off by the burning end of a cigarette, pipe, or cigar and the smoke exhaled by smokers." According to the American Cancer Society, secondhand smoke is the third-leading preventable cause of death in the United States and kills 38,000-65,000 nonsmokers every year.

The first scientific paper on the harmful effects of secondhand smoke was the Hirayama Study, conducted at the Research Institute at Tokyo's National Cancer Center in 1981. Researchers studied 92,000 nonsmoking wives of smoking husbands and a similarly sized group of women married to nonsmokers. They discovered that nonsmoking wives of husbands who smoked faced a 40 to 90% elevated risk of lung cancer (depending on how frequently their husbands smoked) compared with the wives of nonsmoking husbands.

Other studies have followed. A report by the U.S. Environmental Protection Agency (EPA), Respiratory Health Effects of Passive Smoking: Lung Cancer and Other Disorders (Washington, DC: 1992), concluded that the "widespread exposure to environmental tobacco smoke (ETS) in the United States presents a serious and substantial public health impact." In 1994 the largest case-control study on secondhand smoke was conducted, which found compelling links between passive smoke and lung cancer. In 2000 the Environmental Health Information Service's Ninth Report on Carcinogens classified secondhand smoke as a Group A (Human) Carcinogen—a substance known to cause cancer in humans. According to the EPA, there is no safe level of exposure to such Group A toxins.

In 2005 more evidence accumulated on the risks of passive smoking. Findings from a European study revealed that those who had been exposed to secondhand smoke during childhood for many hours each day had more than triple the risk of developing lung cancer compared with people who were not exposed (The EPIC Prospective Study Group, "Environmental Tobacco Smoke and Risk of Respiratory Cancer and Chronic Obstructive Pulmonary Disease in Former Smokers and Never Smokers in the EPIC Prospective Study," British Medical Journal, vol. 330, no. 7486, 2005). In addition, results of a Hong Kong study showed that there was a correlation between an increased risk of dying from various causes (including lung cancer and other lung diseases, heart disease, and stroke) and the number of smokers in the home. Thus, risk increased by 24% when one smoker lived in the home and by 74% with two smokers in the household (S. M. McGhee et al., "Mortality Associated with Passive Smoking in Hong Kong," British Medical Journal, vol. 330, no. 7486, 2005).

Below are some discoveries that have been made about secondhand smoke.

• A person living with a spouse who smokes has a 20 to 50% increased risk of developing lung cancer, according to the EPA report Respiratory Health Effects of Passive Smoking: Lung Cancer and Other Disorders.
• A 1997 study published in the American Heart Association's journal Circulation found that nonsmoking women who were regularly exposed to passive smoke either at work or in the home had a 91% higher risk of heart attack or death than those who were not subjected to the smoke.
• 43% of children are exposed to secondhand smoke in their own homes and 85% of children have detectable levels of cotinine (a chemical indicator of how much cigarette smoke enters the body) in their blood (American Lung Association Fact Sheet on Secondhand Smoke and Children, June 2002).
• Exposure to smoke may also account for 10 to 35% of chronic middle-ear problems in children. This exposure also contributed to an estimated 150,000 to 300,000 lower respiratory tract infections (such as bronchitis and pneumonia) in children eighteen months and younger (EPA and the American Lung Association Fact Sheets).
• According to the EPA, secondhand smoke is thought to have worsened the conditions of 200,000 to one million asthmatic children. Exposure is a risk factor for new cases of asthma in children who have not previously displayed symptoms.
• Some adults are more susceptible to harm from ETS exposure because of their age or health status. People with certain chronic conditions, such as asthma, allergies, and chronic lung disease, may be more susceptible to the harmful effects of secondhand smoke.

Robert M. Davis, M.D., in "Exposure to Environmental Tobacco Smoke" (Journal of the American Medical Association, December 1998), observed that nearly everyone in the United States is at some risk of harm from secondhand smoke. The longer the time spent in a smoking environment and the greater the concentration of ETS in that airspace, the more risk for harm. The concentration of secondhand smoke is affected by the size of the space, the number of people smoking there, and the ventilation rate. In 2000 the CDC reported that the proportion of survey respondents from seventeen states and the District of Columbia who reported a smoke-free policy at their indoor workplace ranged from 61.3 to 82%.

Movement to Ban Smoking

Numerous efforts have been initiated over the years to control public smoking or to separate smokers and non-smokers. In 1975 the Clean Indoor Air Act in Minnesota became the nation's first statewide law to require the separation of smokers and nonsmokers. The purpose of the law was to protect public health, public comfort, and the environment by banning smoking in public places and at public meetings, except in designated smoking areas.

Other states soon followed Minnesota. In 1977 Berkley became the first community in California to limit smoking in restaurants and other public places. In 1990 the city of San Luis Obispo, California, became the first city to ban smoking in all public buildings, bars, and restaurants. In 1994 smoking was restricted in many government buildings in California. In that same year, the fast-food giant McDonald's banned smoking in all of its establishments. In 1995 New York City banned smoking in the dining areas of all restaurants with more than thirty-five seats. As of July 2003, all public and work places in New York City became smoke-free, including bars and restaurants. Laws vary from state to state and from city to city, but by 2005 smoking was banned in most workplaces, hospitals, government buildings, museums, schools, theaters, and many restaurants throughout the United States.

For many years, members of the tobacco industry challenged reports about the harmful effects of smoking. This has been particularly true on the issue of secondhand smoke. The Tobacco Institute placed newspaper ads to discredit the influential 1981 Japanese study. In 1993 tobacco companies filed a suit against the EPA after its report Respiratory Effects of Public Smoking: Lung Cancer and Other Disorders was published. Among the suit's claims were that nonsmokers are normally exposed to very little secondhand smoke and that other factors, such as diet and medical care, might affect the likelihood of children developing diseases. The case was later dismissed. A study published in the May 17, 2003, issue of the British Medical Journal asserted that environmental tobacco smoke may not affect lung cancer rates. The report, funded by the tobacco industry, was criticized by numerous researchers, who called its methodology flawed.

FIGURE 5.9
Public opinion on secondhand smoke, 1994-2003
SOURCE: Lydia Saad, "Perceived Risk of Secondhand Smoke," in Secondhand Smoke a Second-Rate Risk? Americans Resist Severe Public Smoking Restrictions, Gallup Poll News Service, August 4, 2003. Copyright © 2003 by The Gallup Organization. Reproduced by permission of The Gallup Organization.

The public appears to believe that secondhand smoke is linked to health problems. A 2003 Gallup Poll revealed that 51% of those surveyed perceived the risk of secondhand smoke to be very harmful. Approximately half of those questioned have responded this way in Gallup surveys since 1996. (See Figure 5.9.)