Secondhand smoke causes heart disease and lung cancer. In the United States, it accounts for roughly 42,000 heart-related deaths and 7,000 lung cancer deaths among non-smokers yearly, the American Cancer Society reports. Secondhand smoke ranks as the third, after active smoking and alcohol, leading cause of early death in the United States, according to the University of Minnesota Division of Periodontology. More than 4,000 different chemicals and up to 200 known toxins constitute secondhand smoke.
Secondhand smoke increases the frequency of asthmatic attacks in up to 1 million children, and the prevalence of lung infections such as asthma, bronchitis and pneumonia in children below 18 months every year, explains the American Cancer Society. The risk of sudden infant death syndrome rises in infants who inhale secondhand smoke, the Centers for Disease Control and Prevention report.
Smokers inhale roughly 15 percent of cigarette smoke, with the remainder lingering in the air and causing harm to non-smokers. The Environmental Protection Agency ranks secondhand smoke as a Class A carcinogen, a cancer-causing agent in humans. Nicotine ingested by a pregnant woman through secondhand smoke passes to her unborn child, according to the University of Minnesota Division of Periodontology. The risk of miscarriage, low birth weight infants and the birth of children with impaired lung function increases among women exposed to secondhand smoke.