Secondhand smoke, also known as passive or environmental tobacco smoke (ETS), is a combination of:

• Mainstream smoke: exhaled by smokers
• Sidestream smoke: given off by the burning end of a cigarette, cigar, or pipe

Between 70% and 90% of non-smokers in the American population, children and adults, are regularly exposed to secondhand smoke. It is estimated that only 15% of cigarette smoke gets inhaled by the smoker. The remaining 85% lingers in the air for everyone to breathe. If a person spends more than two hours in a room where someone is smoking, the nonsmoker inhales the equivalent of four cigarettes.
Secondhand smoke is the third leading preventable cause of disability and early death (after active smoking and alcohol) in the United States. For every eight smokers who die from smoking, one innocent bystander dies from secondhand smoke.

Secondhand smoke contains over 4000 chemicals including more than 40 cancer causing agents and 200 known poisons.
Secondhand smoke has been classified by the EPA as a Class A carcinogen - a substance known to cause cancer in humans.
Secondhand smoke contains twice as much tar and nicotine per unit volume as does smoke inhaled from a cigarette. It contains 3X as much cancer-causing benzpyrene, 5X as much carbon monoxide, and 50X as much ammonia. Secondhand smoke from pipes and cigars is equally as harmful, if not more so (Mayo Clinic release, Aug 97).

Over the past two decades, medical research has shown that non-smokers suffer many of the diseases of active smoking when they breathe secondhand smoke.
Secondhand smoke causes lung cancer and contributes to the development of heart disease. Never smoking women who live with a smoker have a 91% greater risk of heart disease. They also have twice the risk of dying from lung cancer.
Never-smoking spouses who are exposed to secondhand smoke have about 20% higher death rates for both lung cancer and heart disease.
Secondhand smoke increases heart rate and shortens time to exhaustion. Repeated exposure causes thickening of the walls of the carotid arteries (accelerates atherosclerosis) and damages the lining of these arteries.

When a pregnant woman is exposed to secondhand smoke, the nicotine she ingests is passed on to her unborn baby.
Women who smoke or are exposed to secondhand smoke during pregnancy:

• have a higher rate of miscarriges and stillbirths
• have an increased risk of low birthweight infants
• have children born with decreased lung function
• have children with greater risk of sudden infant death syndrome (SIDS)

Children exposed to secondhand smoke are more likely to experience increased frequency of:

• asthma, colds, bronchitis, pneumonia, and other lung diseases
• middle ear infections
• sinus infections
• caries in deciduous teeth

Ventilation systems and designated smoking sections do not protect patrons from ETS.
Current estimates of how smoking increases the risk of various diseases are dramatically underestimated because the ill effects of secondhand smoke inhalation are not taken into account.