Secondhand smoke is tobacco smoke that affects a nonsmoker.
Secondhand smoke can come directly from a cigarette or other lit tobacco; it
may also be exhaled by a person smoking.
Secondhand smoke is sometimes referred to as environmental tobacco
smoke (ETS), involuntary smoking, or passive smoking.
Secondhand smoke contains the same cancer-causing and lung-damaging
chemicals that affect smokers. Repeated exposure to secondhand smoke over many
years can cause damage to a nonsmoker's lungs that is similar to that of a
Secondhand smoke is the most important risk factor for cancer among
nonsmokers, far greater than other known cancer-causing substances. Secondhand
smoke is most harmful to:
The spouse and any child of a person who smokes, or anyone who
lives with someone who smokes.
A developing fetus, if the pregnant woman smokes.
People who spend most of their time in
confined areas that are filled with tobacco smoke.