Definition of ETS

Reviewed on 3/29/2021

ETS: Environmental tobacco smoke. Smoke generated from the sidestream (the burning end) of a cigarette, pipe or cigar and the exhaled mainstream smoke (the smoke that is puffed out by smokers) of cigarettes, pipes, and cigars.

In 1992, the US Environmental Protection Agency (EPA) completed its risk assessment on "The Respiratory Health Effects of Passive Smoking: Lung Cancer and Other Disorders" and concluded that the widespread exposure to ETS in the United States presented a serious and substantial public health impact. More specifically, EPA concluded that ETS is a human lung carcinogen, responsible for approximately 3,000 lung cancer deaths annually in US nonsmokers. Furthermore, infants and young children are especially sensitive to ETS. In children, ETS exposure is causally associated with:

  1. An increased risk of lower respiratory tract infections such as bronchitis and pneumonia. (EPA estimates that 150,000 to 300,000 cases annually in infants and young children up to 18 months are attributable to ETS.)
  2. An increased prevalence of fluid in the middle ear, symptoms of upper respiratory tract irritation, and small reductions in lung function, and
  3. Additional episodes and increased severity of symptoms in children with asthma. (EPA estimates that up to 1 million asthmatic children have their condition worsened by exposure to ETS.) ETS exposure may also be a risk factor for the development of new cases of asthma.

Environmental tobacco smoke was classified as a "known human carcinogen" by the US government in 2000, based on the causal relationship observed between passive exposure to tobacco smoke and human lung cancer and based also on studies that have conclusively shown an increased risk of lung cancer in nonsmoking women living with smoking husbands or working with smoking co-workers.

Environmental tobacco smoke is also called second-hand smoke. Inhaling ETS is called involuntary or passive smoking.


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