What Is It?
Secondhand smoke, also known as environmental tobacco smoke (ETS) or passive smoke, is a mixture of 2 forms of smoke from burning tobacco products:
- Sidestream smoke: smoke that comes from the end of a lighted cigarette, pipe, or cigar
- Mainstream smoke: smoke that is exhaled by a smoker
When nonsmokers are exposed to secondhand smoke it is called involuntary smoking or passive smoking. Nonsmokers exposed to secondhand smoke absorb nicotine and other compounds just as smokers do. The greater the exposure to secondhand smoke, the greater the level of these harmful compounds in your body.
Why Is It a Problem?
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.
Secondhand tobacco smoke contains over 4,000 chemical compounds. More than 60 of these are known or suspected to cause cancer.
Secondhand smoke can be harmful in many ways. In the United States alone, each year it is responsible for:
- an estimated 35,000 to 40,000 deaths from heart disease in people who are not current smokers
- about 3,000 lung cancer deaths in nonsmoking adults
- other respiratory problems in nonsmokers, including coughing, phlegm, chest discomfort, and reduced lung function
- 150,000 to 300,000 lower respiratory tract infections (such as pneumonia and bronchitis) in children younger than 18 months of age, which result in 7,500 to 15,000 hospitalizations
- increases in the number and severity of asthma attacks in about 200,000 to 1 million asthmatic children
- increases in the risk of sudden infant death syndrome (SIDS) and middle ear infections in young children
- low birth weight in babies whose mothers are exposed to ETS
The 1986 US Surgeon General's report on the health consequences of involuntary smoking reached 3 important conclusions about secondhand smoke:
- Involuntary smoking causes disease, including lung cancer, in healthy nonsmokers.
- When compared with the children of nonsmoking parents, children of parents who smoke have more frequent respiratory infections, more respiratory symptoms, and slower development of lung function as the lung matures.
- Separating smokers and nonsmokers within the same air space may reduce, but does not eliminate, the exposure of nonsmokers to secondhand smoke.
Some studies have also suggested that ETS may be linked to an increased risk of breast cancer. The California Environmental Protection Agency recently concluded that ETS causes breast cancer in younger, mainly premenopausal women. The US Surgeon General is currently reviewing the evidence on this link, and a report is expected in late 2006.
Where Is It a Problem?
There are 3 locations where you should be especially concerned about exposure to secondhand smoke:
There is no research in the medical literature about the cancer-causing effects of cigarette odors, but the literature shows that secondhand tobacco smoke can permeate the hair, clothing, and other surfaces. The unknown cancer causing effects would likely be minimal in comparison to direct secondhand smoke exposure, such as living in a household that has a smoker.