Most everyone knows that smoking is harmful, but the effects of secondhand smoke are not
as clearly understood. Secondhand smoke, which is also called environmental tobacco smoke, is
the combination of smoke that is exhaled by a smoker and the smoke that comes from the burning
end of a tobacco product. Most secondhand smoke comes from cigarettes, but some also comes
from pipes and cigars. With secondhand smoke, people are exposed to smoke without choosing to
smoke themselves.