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Secondhand smoke (SHS), also known as environmental tobacco smoke, is a mixture of the sidestream smoke released by the smoldering cigarette and the mainstream smoke that is exhaled by the smoker. Like mainstream smoke, it is a complex mixture containing thousands of chemicals, including formaldehyde, cyanide, carbon monoxide, ammonia, and nicotine. At least 250 chemicals in SHS are known to be toxic and/or cancer causing agents.
Conclusive scientific evidence documents that SHS causes premature death and disease in children and in adults who do not smoke. Exposure of adults to SHS has immediate adverse effects on the cardiovascular system and causes coronary heart disease and lung cancer. Children exposed to SHS are at increased risk for sudden infant death syndrome (SIDS), acute respiratory infections, middle ear disease, more severe asthma, respiratory symptoms, and slowed lung growth. In 2005, the California Environmental Protection Agency estimated that SHS exposure causes approximately 3,400 lung cancer deaths and approximately 46,000 heart disease deaths among nonsmoking adults in the United States annually, as well as causing 430 SIDS deaths annually among U.S. infants. There is no risk-free level of exposure to SHS, and only eliminating smoking in indoor spaces fully protects nonsmokers from exposure to SHS.
Presented here are three measures of progress in this area:
The third measure, smoke-free laws, draws on data collected and analyzed by the Americans for Nonsmokersí Rights Foundation. The change has been made to allow the inclusion of both local and state laws, and to ensure consistency with the NCI Smoke-free Meeting Policy. For more information see: http://dccps.nci.nih.gov/tcrb/smokefreemeetingpolicy.html.
Over the last few decades, the nation has made enormous progress in reducing nonsmokersí SHS exposure. The first graph shows that the percentage of nonsmokers exposed to SHS has been declining during the period 1988Ė2002, with a non-significant increase between the last two two-year periods (2001–02 to 2003–2004). Both the long-term and the more recent trends are observed in both males and females. The proportion of nonsmokers (four years of age and older) with detectable levels of cotinine, a marker for SHS, in their blood has been approximately halved over the period 1988–1994 to 2003–2004, from 88 to 47 percent. For nonsmoking adults aged 20 years and older, a decline of more than 77 percent has been seen between 1988–1991 and 2001–2002 (Surgeon General Report, 2006).
Indoor workers reported a steep rise in smoke-free workplace policies from 1992–1993 to the mid 1990s. This increase continued, but less steeply, between 1995–1996 and 2001–2002. The most recent period, 2001–2002 to 2003, shows a steeper rise—again coincident with the increases in the percentage of the population protected by local and state smoke-free workplace laws. The patterns are similar for men and women and for young adult workers and adult workers aged 25 years and older. Patterns also appear similar for different racial and ethnic groups.
The percentage of the U.S. population protected by comprehensive local and state smoke-free laws covering workplaces, restaurants, and bars has been rising, although no significant change in this area was observed during some periods in the mid-to-late 1990s. The earliest rise in these measures occurred in the early-to-mid 1990s, with early smoking restrictions in California and Massachusetts and an infusion of funding for evidence-based state tobacco control interventions from National Cancer Instituteís/American Cancer Societyís American Stop Smoking Intervention Study (ASSIST), and some funding for these types of interventions from the Centers for Disease Control and Prevention (CDC), and The Robert Wood Johnson Foundationís SmokeLess States initiative. In contrast, the largest absolute gain in enactment of smoke-free laws covering workplaces, restaurants, and bars, has occurred over the past 10 years, with the greatest increases, especially in state smoke-free laws, seen over the recent five-year period of 2002–2007.
Note: The data source has been changed to one that provides information on both state and local legislative activity.
The estimate of U.S. nonsmokers aged 4 years and older currently (2003–04) exposed to SHS is 47 percent. Thus, nearly 50 percent of nonsmokers 4 years and older are still exposed to SHS (most current value from the 2003–2004 National Health and Nutrition Examination Survey [NHANES]).
The most recent NHANES 2001–04 data reveals that children aged 4–17 years having any detectable level of cotinine in the blood is 57 percent, down from 87 percent during the period 1988–1994. Thus, nearly 60 percent of children aged 4–17 years are still exposed to SHS.
In 2003, 78 percent of indoor workers aged 18 years and older reported that a smoke-free policy was in place at their workplace, with 74.8 percent of men and 81 percent of women reporting the presence of such a policy. Among workers 25 years of age and older, 79 percent worked at a smoke-free worksite, as opposed to only 70 percent of workers aged 18–24 years. Also during that time, 74 percent of all adults aged 18 years and older reported that smoking is not allowed anywhere in their home. These figures represent significant increases since 1992–1993.
As of August 2007, 21 states plus the District of Columbia are nearly or entirely smoke-free according to NCI's Smoke-free Meeting Policy or will be by the beginning of 2008. There are only 11 states that contain no smoke-free jurisdictions. According to the American Nonsmokersí Rights Foundation as of October 1, 2007 40 percent, 56 percent, and 44 percent of Americans lived in a community where they were covered by a state or local smoke-free law making workplaces, restaurants, and bars, respectively, smoke-free. One in four Americans lived in a community where all three of these settings were smoke-free by law, while 59% of Americans were covered by a smoke-free law in at least one of these settings.
Reduce the proportion of children who are regularly exposed to tobacco smoke at home to 6 percent.
Reduce the proportion of nonsmokers exposed to secondhand smoke to 63 percent.
Increase the proportion of persons covered by indoor worksite policies that prohibit smoking to 100 percent.
Increase the number of jurisdictions (States and the District of Columbia) with smoke-free indoor air laws that prohibit smoking in public places and work sites to 51.
Nonsmokersí exposure to SHS has declined broadly in recent years; declines have been observed in both children and nonsmoking adults, for adults aged 18–24 years and 25 years and older, in both men and women, and in all racial and ethnic groups. However, significant levels of exposure persist. In particular, people who work in restaurants, bars, casinos, and some other hospitality industry worksites are far less likely to be protected from SHS exposure than other workers, and are likely to be exposed to especially high levels of SHS on the job.
Adult working men are less likely than adult working women to report being protected by smoke-free workplace policies. Similarly, 18–24-year-old working adults are less likely than working adults aged 25 years and older to be covered by such policies.
The most recent data suggest that, on average, concentrations of cotinine in childrenís blood are more than twice those in nonsmoking adults' blood.
Cotinine levels in nonsmokersí blood have declined in all racial and ethnic groups, but levels have consistently been found to be higher in African Americans than in Whites and Mexican Americans. SHS exposure also tends to be higher for persons with lower incomes.
Exposure to SHS remains a serious public health concern, and one that is completely preventable. Childrenís SHS exposure continues to exceed that of adults, and the home is the single most important setting where children are exposed. Data from the 2003 Tobacco Use Supplement to the Current Population Survey suggest that homes with at least one adult smoker and at least one child under the age of 18 are potentially exposing children in 55 percent of these homes to SHS by virtue of not having a smoke-free home rule. Special efforts should be targeted to parents and guardians who smoke to convince them to make their homes and cars smoke-free. They should be assisted to quit smoking to protect their own health, to protect their children from SHS exposure, and to reduce the likelihood that their children will become smokers.
Additionally, efforts should focus on helping all parents and guardians, including nonsmokers, ensure that their children are not exposed to SHS by avoiding public places—such as restaurants and child care facilities—that do not prohibit smoking and making their homes and cars smoke-free.
Smoke-free laws effectively protect nonsmokers from SHS exposure and appear to yield health benefits soon after implementation. They help educate the public about the serious health consequences of SHS exposure, help change social norms about smoking, and help smokers quit. Three states, the Territory of Puerto Rico, and at least four local jurisdictions in the United States have enacted laws making it illegal to smoke in a vehicle when a child is present. Like seat belt laws, these laws could potentially be accompanied by public education campaigns.
Momentum toward the passage of smoke-free laws has accelerated in recent years. These laws typically enjoy broad public support, which usually increases after the laws take effect. Today, hundreds of communities, many states, and several countries (including Ireland, the entire United Kingdom, Norway, Italy, France, and Uruguay) have such laws in place. Laws are increasingly covering restaurants, bars, casinos, and other worksites that in the past were often exempt. Contrary to concerns voiced by the tobacco industry, peer-reviewed studies using objective measures have consistently found that smoke-free laws have not had a negative economic impact on restaurants and bars.
Despite recent progress, many nonsmoking adults and children remain exposed to SHS. As SHS exposure in enclosed workplaces and public places has decreased due to the implementation of smoke-free policies, the home has become a more important source of exposure, even for adults.
Through a variety of tactics, the tobacco industry has long sought to undermine the credibility of the scientific evidence on the health effects of SHS and to impede the adoption of smoke-free policies in workplaces and public places. These activities have slowed progress toward protecting the public from the hazards of SHS exposure and have harmed the publicís health.