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Cancer Trends Progress Report – 2011/2012 Update

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Smoking Initiation
Youth Smoking
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Fruit and Vegetable Consumption
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> Secondhand Smoke
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Secondhand Smoke
Prevention: Environmental Factors

Much progress has been made in reducing secondhand smoke exposure over the past decade. More than a 50 percent reduction has occurred among nonsmokers overall. Yet young children (54 percent), adolescents (46 percent), and young adults (54 percent) still had greater exposure than adults 30 years and older (34 percent) from 2007 to 2008.

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Secondhand Smoke and Cancer

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 exhaled by the smoker. Like mainstream smoke, SHS 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 adults who do not smoke. Exposure to SHS by adults 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 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. In 2009, the Institute of Medicine conducted a comprehensive review of the impact of smoke-free legislation and determined that “data consistently demonstrate that SHS exposure increases the risk of coronary heart disease and heart attacks and that smoking bans reduce heart attacks.”

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Presented here are four measures of progress in this area:

  1. Percentage of nonsmokers exposed to SHS. (The percentage of nonsmokers aged 3 years and older with a serum cotinine level greater than 0.05 ng/mL less than or equal to 10 ng/mL).
  2. Percentage of indoor workers reporting a smoke-free work environment.
  3. Percentage of respondents reporting a smoke-free home policy.
  4. Percentage of the population protected by local and state smoke-free indoor air laws covering workplaces, restaurants, and bars.

The fourth measure, smoke-free laws, draws on data collected and analyzed by the Americans for Nonsmokers’ Rights Foundation. Use of this information provides inclusion of both local and state laws and ensures consistency with the NCI Smoke-free Meeting Policy. For more information, see

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  1. Secondhand smoke: 1988–2008
  2. Smoke-free work environment: 1992–2010
  3. Smoke-free home policy: 1992–2010
  4. Smoke-free indoor air laws: 1992–2010

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Secondhand Smoke Exposure

Over the past few decades, the nation has made enormous progress in reducing nonsmokers’ SHS exposure. The first graph shows that the percentage of nonsmokers exposed to SHS was generally declining from 1988 to 2008. The proportion of nonsmokers (3 years of age and older) with detectable levels of cotinine, a marker for SHS, in their blood was more than halved—from 84 percent (from 1988 to 1994) to 41 percent (from 2007 to 2008).

This downward trend slowed between 2002 and 2008. Both the long-term steep falling trend and the more recent non-significant declines are seen for both males and females. While all three race/ethnicity categories show a downward trend, the decline in SHS exposure from 1988 to 1994 to 2007 to 2008 has been statistically significantly steeper among Hispanics (47 percentage point decline) compared to non-Hispanic Blacks (38 percentage point decline).

Trends in serum cotinine levels are similar by age, except that those recent declines for ages 3 to 11 and 12 to 17 are statistically significant, and the recent period estimates for ages 18 to 29 are stable. Trends in serum cotinine levels are similar by education and poverty status, although higher-income populations seem to show somewhat larger statistically significant recent declines than lower-income populations.

Smoke-free Work Environment

Overall, indoor workers reported large increases in smoke-free work environments from 1992 to 2010.

The patterns are similar for males and females, as well as for adults in groups aged 18 to 24 years and 25 years and older.

Smoke-free workplace trends are also similar by education, poverty status, and race/ethnicity, although the increase among Hispanics was not statistically significant.

Smoke-free Home Policy

There was an overwhelming increase in smoke-free home environments between 1992 and 1993 (43 percent) and 2009 and 2010 (84 percent). There was a sharp rise in smoke-free home environments from 1992 to 2003, although this rise continued—albeit less steeply and typically statistically non-significant—between 2003 and 2010. This trend is similar by sex, age, race/ethnicity, education, and poverty status, with the exception of a statistically significant rising trend for non-Hispanic blacks and males aged 18 to 24 years.

Population Covered by Local and State Smoke-free Indoor Air Laws

Trends for the percentage of the population covered by local and state indoor air laws have been steeply rising since 2001 after a slow non-significant increase between 1993 and 2001 for workplaces and between 1998 and 2001 for restaurants and bars.

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Most Recent Estimates

Secondhand Smoke Exposure

From 2007 to 2008, the estimate of U.S. nonsmokers aged 3 years and older currently exposed to SHS was 41 percent (44 percent for males; 39 percent for females). Thus, nearly 40 percent of nonsmokers aged 3 years and older were still exposed to SHS.

The most recent cotinine data for 2007 to 2008 for children aged 3 to 11 years reveal that 54 percent had detectable levels of cotinine in their blood, which is down from 85 percent from 1988 to 1994. Thus, just over half of all children aged 3–11 years are still exposed to SHS. The 2007 to 2008 data also indicate that 46 percent of children aged 12 to 17 years, 54 percent of young adults aged 18 to 29 years, and 34 percent of adults aged 30 years and older are exposed to SHS.

Smoke-free Work Environment

In May 2010, 81 percent of indoor workers aged 18 years and older reported that a smoke-free policy was in place at their workplace, with 78 percent of men and 84 percent of women reporting the presence of such a policy. Among workers aged 25 years and older, 79 percent of males and 84 percent of females worked at a smoke-free workplace, as opposed to only 76 percent of male workers and 80 percent of female workers aged 18 to 24 years.

Smoke-free Home Policy

About 84 percent of men and women reported their homes were smoke-free (83 percent of males and 85 percent of females). Similar levels were seen for both young adults aged 18–24 years (80 percent of males and 84 percent of females) as well as those aged 25 years and older (83 percent of males and 85 percent of females).

Population Covered by Local and State Smoke-free Indoor Air Laws

As of October 2011, there were 31 states, as well as Puerto Rico and Washington, D.C., that had laws that provide complete or nearly complete protection from SHS, according to NCI’s Smoke-free Meeting Policy. There were 13 additional states that contain at least one smoke-free jurisdiction. Only six states had no jurisdictions that meet NCI’s standards for smoke-free policies. According to the American’s for Nonsmokers’ Rights Foundation External link ( External link), as of April 2012, 63 percent, 75 percent, and 64 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. Americans in 23 states, along with Puerto Rico, the U.S. Virgin Islands, and Washington, D.C., which represents 48 percent of the population, lived in a community where all three of these settings were smoke-free by law. Meanwhile, Americans in 39 states plus Washington, D.C., representing 80 percent of the population, were covered by a local or state 100 percent smoke-free law in at least one of these settings, while 35 states were covered by a state 100 percent smoke-free law.

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Healthy People 2020 Targets

Reduce the proportion of children aged 3 to 11 years who are regularly exposed to tobacco smoke to 47 percent.

Reduce the proportion of children aged 12 to 17 years who are regularly exposed to tobacco smoke to 41 percent.

Reduce the proportion of nonsmokers exposed to secondhand smoke to 33.8 percent.

Increase the proportion of persons covered by indoor worksite policies that prohibit smoking to 100 percent.

Increase the proportion of smoke-free homes to 87 percent.

Increase the number of jurisdictions (states and Washington, D.C.) with smoke-free indoor air laws that prohibit smoking in public places and work sites to 51.

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Groups at High Risk for Exposure to Secondhand Smoke

Nonsmokers’ exposure to SHS has declined broadly in recent years; declines have been observed in both children and nonsmoking adults. However, significant levels of exposure to SHS persist. The most recent data suggest that, on average, concentrations of cotinine in children’s and young adults’ blood are more than those in nonsmoking adolescents’ and older adults’ blood. Cotinine levels in children’s and nonsmokers’ blood (aged 3 years and older) have declined in all racial/ethnic groups, but levels have consistently been higher in non-Hispanic blacks than in both non-Hispanic whites and Hispanics. Male adult SHS exposure estimates are higher than female adult exposure estimates. SHS exposure also tends to be higher for individuals with lower incomes and lower levels of education.

Adult working men are less likely than adult working women to report being protected by smoke-free workplace policies. Similarly, 18 to 24-year-old working adults are less likely than working adults aged 25 years and older to be covered by such policies. Among those aged 25 years and older, the percentage of workers reporting a smoke-free work environment decreases with lower levels of education. Additionally, lower-income working respondents are less likely to report a smoke-free workplace.

In particular, people who work in casinos, some other hospitality industry worksites, and blue-collar worksites are far less likely to be protected from SHS exposure than other workers, and they are likely to be exposed to especially high levels of SHS on the job.

Non-Hispanic blacks (79 percent) and non-Hispanic whites (83 percent) report having a smoke-free home environment less frequently than Hispanics (90 percent). Those with less than a high school diploma and with a high school diploma report a lower percentage of smoke-free home policies when compared to those with more than a high school education. Likewise, smoke-free home policies are less common among lower-income individuals compared to those with higher incomes. Also, although both smokers’ and nonsmokers’ reports of smoke-free home policies have increased since 1992, smokers still report lower levels of smoke-free home policies than nonsmokers.

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Key Issues

Exposure to SHS remains a serious public health concern, and one that is completely preventable. Children’s SHS exposure continues to exceed that of adults, and the home is the single most important setting where children are exposed. 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. EPA and HHS are supporting activities and research involving pediatricians counseling parents who smoke about the dangers of SHS for their children in an attempt to accomplish these three goals. Additionally, efforts should focus on helping all parents and guardians, including nonsmokers, ensure that their children are not exposed to SHS—for instance, by avoiding public places, such as restaurants, 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. Some U.S. states, territories, and localities 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. North Carolina, a tobacco growing state, passed a strong clean indoor air law in the spring of 2009 that protects its citizens from tobacco smoke in the workplace. Today, hundreds of communities, many states, and several countries (including Ireland, the United Kingdom, Norway, Italy, France, and Uruguay) have such laws in place. Laws are increasingly covering restaurants, bars, casinos, and other worksites that were often exempt in the past. 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, and in many instances, such laws have actually had a positive economic impact.

Despite recent progress in reduced SHS exposure, many nonsmoking adults and children remain exposed to SHS. As SHS exposure in enclosed workplaces and public places has decreased because of the implementation of smoke-free policies, the home has become a more important source of exposure, even for adults. Efforts to reduce SHS exposure have expanded to making multi-unit housing complexes smoke-free.

Through a variety of tactics, the tobacco industry has long sought to undermine the credibility of the scientific evidence on the adverse 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 public’s health.

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Additional Information on Secondhand Smoke

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