Secondhand Smoke

What is secondhand smoke?

Secondhand smoke (SHS) is also known as environmental tobacco smoke (ETS). SHS is a mixture of 2 forms of smoke that come from burning tobacco:

• Sidestream smoke – the smoke that comes from the end of a lighted cigarette, pipe, or cigar

and

• Mainstream smoke – the smoke that is exhaled by a smoker

Even though we think of these as the same, they aren’t. The sidestream smoke has higher concentrations of cancer-causing agents (carcinogens) than the mainstream smoke. And, it contains smaller particles than mainstream smoke, which make their way into the body’s cells more easily.

When non-smokers are exposed to SHS it is called involuntary smoking or passive smoking. Non-smokers who breathe in SHS take in nicotine and other toxic chemicals just like smokers do. The more SHS you are exposed to, the higher the level of these harmful chemicals in your body.

Why is secondhand smoke a problem?

Secondhand smoke causes cancer

Secondhand smoke is classified as a “known human carcinogen” (cancer-causing agent) by the US Environmental Protection Agency (EPA), the US National Toxicology Program, and the International Agency for Research on Cancer (IARC), a branch of the World Health Organization.

Tobacco smoke contains more than 7,000 chemical compounds. More than 250 of these chemicals are known to be harmful, and at least 69 are known to cause cancer.

SHS has been linked to lung cancer. There is also some evidence suggesting it may be linked with childhood leukemia and cancers of the larynx (voice box), pharynx (throat), brain, bladder, rectum, stomach, and breast.

Secondhand smoke and breast cancer

Whether SHS increases the risk of breast cancer is an issue that is still being studied. Both mainstream and SHS contain about 20 chemicals that, in high concentrations, cause breast cancer in rodents. And we know that in humans, chemicals from tobacco smoke reach breast tissue and are found in breast milk.

But a link between SHS and breast cancer risk in human studies is still being debated. This is partly because breast cancer risk has not been shown to be increased in active smokers. One possible explanation for this is that tobacco smoke may have different effects on breast cancer risk in smokers and in those who are exposed to SHS.

A report from the California Environmental Protection Agency in 2005 concluded that the evidence regarding SHS and breast cancer is “consistent with a causal association” in younger women. This means the SHS acts as if it could be a cause of breast cancer in these women. The 2006 US Surgeon General’s report, The Health Consequences of Involuntary Exposure to Tobacco Smoke, found that there is “suggestive but not sufficient” evidence of a link at this point.

Research is still being done, but women should be told that this possible link to breast cancer is yet another reason to avoid being around SHS.

Secondhand smoke causes other kinds of diseases and deaths

Secondhand smoke can cause harm in many ways. Each year in the United States alone, it is responsible for:

• An estimated 46,000 deaths from heart disease in people who are current non-smokers
• About 3,400 nonsmoking adults die of lung cancer as a result of breathing SHS
• Worse asthma and asthma -related problems in up to 1 million asthmatic children
• Between 150,000 and 300,000 lower respiratory tract infections in children under 18 months of age, and lung infections resulting in 7,500 to 15,000 hospitalizations each year

Surgeon General’s reports: Findings on smoking, secondhand smoke, and health

Since 1964, 30 separate US Surgeon General’s reports have been written to make the public aware of the health issues linked to tobacco and SHS. The ongoing research used in these reports continues to support the fact that tobacco and SHS are linked to serious health problems that could be prevented. The reports have highlighted many important findings on SHS, such as:

• SHS kills children and adults who don’t smoke.
• SHS causes disease in children and in adults who don’t smoke.
• Exposure to SHS while pregnant increases the chance that a woman will have a spontaneous abortion, still-born birth, low birth- weight baby, and other pregnancy and delivery problems.
• Chemicals in tobacco smoke damage sperm which might reduce fertility and harm fetal development. SHS is known to damage sperm in animals, but more studies are needed to find out its effects in humans.
• Babies and children exposed to SHS are at an increased risk of sudden infant death syndrome (SIDS), acute respiratory infections, ear infections, and more severe and frequent asthma attacks.
• Smoking by parents can cause wheezing, coughing, bronchitis, and pneumonia, and slow lung growth in their children.
• SHS immediately affects the heart, blood vessels, and blood circulation in a harmful way. Over time it can cause heart disease, strokes, and heart attacks.
• SHS causes lung cancer in people who have never smoked. Even brief exposure can damage cells in ways that set the cancer process in motion.
• There is no safe level of exposure to SHS. Any exposure is harmful.
• Many millions of Americans, both children and adults, are still exposed to SHS in their homes and workplaces despite a great deal of progress in tobacco control.
• On average, children are exposed to more SHS than non-smoking adults.
• The only way to fully protect non-smokers from exposure to SHS indoors is to prevent all smoking in that indoor space or building. Separating smokers from non-smokers, cleaning the air, and ventilating buildings cannot keep non-smokers from being exposed to SHS.

Where is secondhand smoke a problem?

You should be especially concerned about exposure to secondhand smoke in these 4 places:

At work

The workplace is a major source of SHS exposure for adults.

SHS is classified as a potential cancer-causing agent by the Occupational Safety and Health Administration (OSHA), the federal agency responsible for health and safety regulations in the workplace. The National Institute for Occupational Safety and Health (NIOSH), another federal agency, also recommends that SHS be considered a possible carcinogen in the workplace. Because there are no known safe levels, they recommend that exposures to SHS be reduced to the lowest possible levels.

SHS in the workplace has been linked to an increased risk for heart disease and lung cancer among adult non-smokers. The Surgeon General has said that smoke-free workplace policies are the only way to do away with SHS exposure at work. Separating smokers from non-smokers, cleaning the air, and ventilating the building cannot prevent exposure if people still smoke inside the building. An extra bonus other than protecting non-smokers is that workplace smoking restrictions may also encourage smokers to smoke less, or even quit.

In public places

Everyone can be exposed to SHS in public places, such as restaurants, shopping centers, public transportation, schools, and daycare centers. The Surgeon General has suggested people choose restaurants and other businesses that are smoke-free, and let owners of businesses that are not smoke-free know that SHS is harmful to your family’s health.

Some businesses seem to be afraid to ban smoking, but there is no proof that going smoke-free is bad for business. Public places where children go are a special area of concern. Make sure that your children’s day care center or school is smoke-free.

At home

Making your home smoke-free may be one of the most important things you can do for the health of your family. Any family member can develop health problems related to SHS.

Children’s growing bodies are especially sensitive to the poisons in SHS. Asthma, lung infections, and ear infections are more common in children who are around smokers. Some of these problems can be serious and even life-threatening. Others may seem like small problems, but they add up quickly – think of the expenses, time for doctor visits, medicines, lost school time, and often lost work time for the parent who must stay home with a sick child.

Think about it: we spend more time at home than anywhere else. A smoke-free home protects your family, your guests, and even your pets.

Multi-unit housing where smoking is allowed is a special concern and a subject of research. Tobacco smoke can move through air ducts, wall and floor cracks, elevator shafts, and along crawl spaces to contaminate apartments on other floors, even those that are far from the smoke. SHS smoke cannot be controlled with ventilation, air cleaning, or by separating smokers from non-smokers.

In the car

Americans spend a great deal of time in cars, and if someone smokes there, the poisons can build up quickly. Again, this can be especially harmful to children.

In response to this fact, the US Environmental Protection Agency has a special program to encourage people to make their cars, as well as their homes, smoke-free. Some states and cities even have laws that ban smoking in the car if carrying passengers under certain ages or weights.

What about smoking odors?

There is no research in the medical literature as yet that shows cigarette odors cause cancer in people. Research does show that particles from secondhand tobacco smoke can settle into dust and onto surfaces and remain there long after the smoke is gone – some studies suggest the particles can last for months. Researchers call this thirdhand smoke or residual tobacco smoke. Studies have shown that the particles that settle out from tobacco smoke can form more cancer-causing compounds.

Though unknown, the cancer-causing effects would likely be small compared with direct exposure to SHS. The compounds may be stirred up and inhaled with other house dust, but more may be absorbed through the skin or accidentally taken in through the mouth. This is why any risk the compounds pose may be larger for babies and children who play on the floor and often put things in their mouths. No actual cancer risk has been measured, but the health risks of thirdhand smoke are an active area of research.

What can be done about secondhand smoke?

Local, state, and federal authorities can enact public policies to protect people from SHS and protect children from tobacco-caused diseases and addiction. Because there are no safe levels of SHS, it is important that any such policies be as strong as possible, and that they do not prevent action at other levels of government.

Many US local and state governments, and even federal governments in some other countries, have decided that protecting the health of employees and others in public places is of the utmost importance. Many have passed clean indoor air laws. Although the laws vary from place to place, they are becoming more common. Detailed information on smoking restrictions in each state is available from the American Lung Association at www.lungusa2.org/slati/.

To learn more

More from your American Cancer Society

We have selected some related information that may also be helpful. These may be read on our Web site or you can order free copies from our toll-free number.

Questions About Smoking, Tobacco, and Health (also in Spanish)

Smoking in the Workplace

Guide to Quitting Smoking (also in Spanish)

Other organizations*

Along with the American Cancer Society, other sources of information and support include:

Environmental Protection Agency (EPA)
Telephone: 202-272-0167
Toll-free number for smoke-free info: 1-866-SMOKE-FREE (1-866-766-5337)
Web site: www.epa.gov

Has advice on how to protect children from SHS, a Smoke-free Homes Pledge, and other tobacco-related materials on the direct Web site, www.epa.gov/smokefree.
Also has specific information on dealing with SHS in apartment buildings at http://iaq.supportportal.com/link/portal/23002/23007/Article/21526/What-can-I-do-about-secondhand-smoke-coming-from-my-neighbor-s-apartmentht.

American Lung Association
Telephone: 1-800-586-4872
Web site: www.lungusa.org

Printed quit materials are available, some in Spanish; also has details on state-specific tobacco/smoking control laws and policies at www.lungusa2.org/slati/.

Centers for Disease Control and Prevention
Office on Smoking and Health
Toll-free number: 1-800-232-4636 (1-800-CDC-INFO)
Web site: www.cdc.gov/tobacco

Offers answers to tobacco-related health questions, a lot of information on tobacco and smoking, and tools and resources for taking action against SHS

National Cancer Institute
Toll-free number: 1-800-422-6237 (1-800-4-CANCER)
Web site: www.cancer.gov
Direct tobacco Web site: www.smokefree.gov

Quitting information is offered, as well as information on smoking by state and information about SHS

No matter who you are, we can help. Contact us anytime, day or night, for information and support. Call us at 1-800-227-2345 or visit www.cancer.org.

References

American Cancer Society. Cancer Facts & Figures 2012. Atlanta, Ga. 2012.

Betts KS. Secondhand Suspicions: Breast Cancer and Passive Smoking. Environ Health Perspect. 2007;115:A136-A143.

Borland R, Yong H-H, Siahpush M, et al. Support for and reported compliance with smoke-free restaurants and bars by smokers in four countries: findings from the International Tobacco Control (ITC) Four Country Survey. Tobacco Control. 2006;15(suppl 3):34-41.

California Environmental Protection Agency. Health Effects of Exposure to Environmental Tobacco Smoke. June 2005. Accessed at www.oehha.ca.gov/air/environmental_tobacco/pdf/app3partb2005.pdf on November 7, 2011.

Centers for Disease Control and Prevention, National Institute of Occupational Safety and Health. Current Intelligence Bulletin 54: Environmental Tobacco Smoke in the Workplace – Lung Cancer and Other Health Effects. 1991. (Publication No. 91-108) Accessed at www.nasdonline.org/document/1194/d001030/environmental-tobacco-smoke-in-the-workplace-lung-cancer.html on November 7, 2011.

Dreyfuss JH. Thirdhand smoke identified as potent, enduring carcinogen. CA Cancer J Clin. 2010;60(4):203-4.

Matt GE, Quintana PJ, Destaillats H, et al. Thirdhand tobacco smoke: emerging evidence and arguments for a multidisciplinary research agenda. Environ Health Perspect. 2011;119(9):1218-26.

Mennella JA, Yourshaw LM, Morgan LK. Breastfeeding and smoking: short-term effects on infant feeding and sleep. Pediatrics. 2007;120:497-502.

National Cancer Institute. Secondhand Smoke and Cancer. Accessed at www.cancer.gov/cancertopics/factsheet/Tobacco/ETS on November 2, 2011.

Pirkle JL, Flegal KM, Bernert JT, et al. Exposure of the US population to environmental tobacco smoke: The Third National Health and Nutrition Examination Survey, 1988 to 1991. JAMA. 1996;275:1233-1240.

Polyzos A, Schmid TE, Piña-Guzmán B, et al. Differential sensitivity of male germ cells to mainstream and sidestream tobacco smoke in the mouse. Toxicol Appl Pharmacol. 2009;237(3):298-305.

Public Health Law Center at William Mitchell College of Law, St. Paul, Minnesota. Kids, Cars and Cigarettes: A Brief Look at Policy Options for Smoke-Free Vehicles. April 2011. Accessed at http://publichealthlawcenter.org/sites/default/files/resources/phlc-guide-kidscarssmoke-policyoptions-2011.pdf on November 4, 2011.

Sleiman M, Gundel LA, Pankow JF, et al. Formation of carcinogens indoors by surface-mediated reactions of nicotine with nitrous acid, leading to potential thirdhand smoke hazards. Proc Natl Acad Sci U S A. 2010;107(15):6576-81.

US Department of Health and Human Services. Report on Carcinogens, 12th Edition. Public Health Service – National Toxicology Program. “Tobacco-Related Exposures,” pp 408-414. Accessed at http://ntp.niehs.nih.gov/ntp/roc/twelfth/profiles/TobaccoRelatedExposures.pdf on November 1, 2011.

US Department of Health and Human Services. Children and Secondhand Smoke Exposure-Excerpts from The Health Consequences of Involuntary Exposure to Tobacco Smoke: A Report of the Surgeon General, 2007. Accessed at www.surgeongeneral.gov/library/smokeexposure/index.html on November 3, 2011.

US Department of Health & Human Services. How Tobacco Smoke Causes Disease: The Biology and Behavioral Basis for Smoking-Attributable Disease: A Report of the Surgeon General. 2010. Accessed at www.surgeongeneral.gov/library/tobaccosmoke/index.html on November 2, 2011.

US Department of Health and Human Services. The Health Consequences of Involuntary Exposure to Tobacco Smoke: A Report of the Surgeon General. 2006. Accessed at www.surgeongeneral.gov/library/secondhandsmoke/ on November 3, 2011.

US Department of Health and Human Services. The Health Consequences of Smoking: A Report of the Surgeon General. 2004. Accessed at www.surgeongeneral.gov/library/smokingconsequences/index.html on November 3, 2011.

US Environmental Protection Agency. Frequent Questions. Indoor Air Quality. What can I do about secondhand smoke coming from my neighbor's apartment? Accessed at http://iaq.supportportal.com/link/portal/23002/23007/Article/21526/What-can-I-do-about-secondhand-smoke-coming-from-my-neighbor-s-apartment on November 4, 2011.

US Environmental Protection Agency. Respiratory Health Effects of Passive Smoking (Also Known as Exposure to Secondhand Smoke or Environmental Tobacco Smoke ETS). US Environmental Protection Agency, Office of Research and Development, Office of Health and Environmental Assessment, Washington, DC; 1992. Accessed at http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=2835 on November 2, 2011.

Winickoff JP, Friebely J, Tanski SE, et al. Beliefs about the health effects of “thirdhand” smoke and home smoking bans. Pediatrics. 2009;123(1):e74-79.

World Health Organization International Agency for Research on Cancer. Evaluating the Effectiveness of Smoke-free Policies, IARC Handbook of Cancer Prevention, Volume 13. 2009. “Chapter 2: Health effects of exposure to secondhand smoke (SHS),” pgs 9-58. Accessed at www.iarc.fr/en/publications/pdfs-online/prev/handbook13/handbook13-2.pdf on November 2, 2011.

World Health Organization International Agency for Research on Cancer. IARC Strengthens Its Findings on Several Carcinogenic Personal Habits and Household Exposures. November 2009. Accessed at www.iarc.fr/en/media-centre/pr/2009/pdfs/pr196_E.pdf on November 2, 2011.