Environmental Tobacco Smoke
Cigarette smoke is called mainstream smoke when inhaled directly from a cigarette. Sidestream smoke is smoke emitted from the burning cigarette and exhaled by the smoker. Sidestream smoke is also called environmental tobacco smoke (ETS) or secondhand smoke. Inhalation of ETS is known as passive smoking. In 1993, the Environmental Protection Agency (EPA) classified ETS as a Group A (known human) carcinogen—the grouping reserved for the most dangerous carcinogens. By 1996, the Department of Health and Human Services' Centers for Disease Control and Prevention (CDC) found that nine out of 10 non-smoking Americans are regularly exposed to ETS. A study by the American Heart Association reported in 1997 that women regularly exposed to ETS have a 91% greater risk of heart attack and those exposed occasionally a 58% greater risk—rates which are believed to apply equally to men. The EPA estimates that, annually, ETS is responsible for more than 3,000 lung cancer deaths, 35,000-62,000 deaths from heart attacks, and lower respiratory tract infections (such as bronchitis [300,000 cases annually] and asthma [400,000 existing cases]), and middle ear infections in children.
ETS may be more carcinogenic than mainstream smoke as it contains higher amounts of carcinogenic materials with smaller particles. These smaller particles are more likely to lodge in the lungs than the larger particles in mainstream smoke. Researchers found that no safe threshold exists for exposure to ETS. With this information, many municipal governments and workplaces have banned cigarette smoking altogether.
Science EncyclopediaScience & Philosophy: Chimaeras to ClusterCigarette Smoke - Environmental Tobacco Smoke, The Health Consequences Of Tobacco Use, Cardiovascular Disease, Cancer, Lung Disease - Components of cigarette smoke