According to the Centers for Disease Control and Prevention (CDC) and the American Cancer Society, secondhand smoke is responsible for at least 35,000 deaths from cardiovascular disease and over 3,000 deaths from lung cancer nationwide each year. The widespread practice of smoking in buildings exposes nonsmoking occupants to combustion by-products under conditions where airborne contaminant removal is slow and uncertain. Secondhand smoke, also known as environmental tobacco or passive smoke, contains at least 250 chemicals known to be toxic or to cause cancer. It meets the criteria to be 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 US Environmental Protection Agency (EPA) classifies secondhand smoke as a Group A carcinogen, which means that there is sufficient evidence that it causes cancer in humans. It also is classified as a "known human carcinogen" by the US National Toxicology Program.
