National Cancer Institute  U.S. National Institutes of Health

Cancer Trends Progress Report – 2009/2010 Update

Skip to content
Progress Report  Home

Progress Report Tools
 Print this page
 Generate custom report

In the Report
Summary Tables
Age at Smoking Initiation
Youth Smoking
Adult Smoking
Quitting Smoking
Clinicians’ Advice to Quit Smoking
Medicaid Coverage of Tobacco Dependence Treatments
Fruit and Vegetable Consumption
Red Meat Consumption
Fat Consumption
Alcohol Consumption
Physical Activity
Sun Protection
> Secondhand Smoke
Tobacco Company Marketing Expenditures
Early Detection
Life After Cancer
End of Life

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.

On this page:

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 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. 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.”

Back to Top


Presented here are four measures of progress in this area:

  1. Percentage of nonsmokers exposed to SHS. (The percentage of nonsmokers aged 4 years and older with a serum cotinine level between 0.05 ng/mL and 11 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

Back to Top


  1. Secondhand smoke: 1988–2006
  2. Smoke-free work environment: 1992–2007
  3. Smoke-free home policy: 1992–2007
  4. Smoke-free indoor air laws: 1992–2009

Back to Top


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 has been declining during the period 1988–2006. The proportion of nonsmokers (4 years of age and older) with detectable levels of cotinine, a marker for SHS, in their blood has been more than halved—from 83 percent (during the period 1988–1994) to 39 percent (during the period 2005–2006).

This downward trend slowed between 2002 and 2006. Both the long-term steep falling trend and the more recent stability are seen for both males and females. While all three race/ethnicity categories show a downward trend, the Black non-Hispanic decline has been shallower and has resulted in only about a 37-percent decline in comparison to the 53-percent and 58-percent declines seen for White non-Hispanics and Hispanics, respectively over the period 1988–1994 to 2005–2006.

Trends in serum cotinine levels are similar by age, education, and poverty status, although older, more highly educated, and higher-income populations seem to show somewhat larger declines.

Smoke-free Work Environment

Overall, indoor workers have reported large increases in smoke-free worksites over the period 1992–2007. In particular, they reported a steep rise in smoke-free workplace policies from 1992 to the mid 1990s. This increase continued, but less steeply, between 1995 and 2002. A steeper rise was noticed again during the period 2001–2003. Finally, during the period 2003–2007, the percentage of workers reporting a smoke-free work environment fell slightly.

The patterns are similar for men and women and among young adults, and those aged 25 years and older.

Smoke-free workplace trends are also similar by race/ethnicity, education, and poverty status.

Smoke-free Home Policy

There has been an overwhelming increase (84 percent) in smoke-free home environments between the periods 1992–1993 (43 percent) and 2006–2007 (79 percent). The rise in smoke-free home policies has been significant during every period over the entire interval. This trend is similar by gender, age, race/ethnicity, education, and poverty level.

Back to Top

Most Recent Estimates

Secondhand Smoke Exposure

The estimate of U.S. nonsmokers aged 4 years and older currently (during the period 2005–2006) exposed to SHS is 39.4 percent (43.4 percent among males and 36.4 percent among females). Thus, nearly 40 percent of nonsmokers aged 4 years and older are still exposed to SHS.

The most recent cotinine data for the period 2005–2006 for children aged 4–11 years reveal that 51 percent have any detectable level of cotinine in the blood, which is down from 85 percent during the period 1988–1994. Thus, just over half of all children aged 4–11 years are still exposed to SHS. The 2005–2006 data also indicate that 44 percent of children aged 12–17 years, 51 percent of young adults aged 18–24 years, and 35 percent of adults aged 25 years and older are exposed to secondhand smoke.

Smoke-free Work Environment

During the period 2006–2007, 76 percent of indoor workers aged 18 years and older reported that a smoke-free policy was in place at their workplace, with 73 percent of men and 78 percent of women reporting the presence of such a policy. Among workers aged 25 years and older, 74 percent of males and 80 percent of females worked at a smoke-free worksite, as opposed to only 65 percent of male workers and 70 percent of female workers aged 18–24 years.

Smoke-free Home Policy

About 80 percent of men and women reported their homes were smoke-free (78 percent of males and 80 percent of females). This level was seen for both young adults aged 18–24 years as well as those aged 25 years and older.

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

As of November 2009, 22 states, as well as Puerto Rico and the District of Columbia have laws that provide complete or nearly complete protection from SHS, according to NCI's Smoke-free Meeting Policy. Only 11 states have no jurisdictions that meet NCI’s standards for smoke-free policies. According to the American’s for Nonsmokers’ Rights Foundation, as of 2009, 57 percent, 65 percent, and 54 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 19 states, representing 41 percent of the population, lived in a community where all three of these settings were smoke-free by law. Meanwhile Americans in 31 states, representing 71 percent of the population, were covered by a smoke-free law in at least one of these settings.

Back to Top

Healthy People 2010 Targets

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.

Back to Top

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 persist. The most recent data suggest that, on average, concentrations of cotinine in children’s blood are more than those in nonsmoking adults' blood. Cotinine levels in children’s and nonsmokers’ blood (aged 4 years and older) have declined in all racial and ethnic groups, but levels have consistently been found to be higher in non-Hispanic Blacks than in both non-Hispanic Whites and Mexican Americans. Male adult exposure estimates are higher than female adult exposure rates. SHS exposure also tends to be higher for persons 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, 18–24-year-old working adults are less likely than working adults aged 25 years and older to be covered by such policies. Among those 25 years and older, the percentage reporting a smoke-free workplace decreases with lower levels of education. Additionally, lower-income 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 (75 percent) and non-Hispanic Whites (78 percent) less frequently report having a smoke-free home policy when compared to Hispanics (88 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 Americans as compared to those with higher incomes. Also, while 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.

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

The percentage of the U.S. population protected by comprehensive local and state smoke-free laws covering workplaces, restaurants, and bars has risen. The first small increases in this measure during the 1990s were the result of early smoking restrictions in California and Massachusetts and an infusion of funding for evidence-based state tobacco control interventions from National Cancer Institute’s/American Cancer Society’s American Stop Smoking Intervention Study for Cancer Prevention (ASSIST), and some funding for these types of interventions from the Centers for Disease Control and Prevention (CDC), and The Robert Wood Johnson Foundation’s SmokeLess States initiative. The largest absolute gain in enactment of smoke-free laws covering workplaces, restaurants, and bars, has occurred over the past 7–10 years. In recent years, states have joined localities in enacting smoke-free laws.

Back to Top

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, 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. Recently, in the spring of 2009, North Carolina, a tobacco growing state, passed a strong clean indoor air law protecting 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 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 public’s health.

Back to Top

Additional Information on Secondhand Smoke

Back to Top

Back: Sun Protection

National Cancer InstituteDepartment of Health and Human ServicesNational Institutes of