As stated by the U.S. Surgeon General, there is no risk-free level of exposure to secondhand smoke.
Secondhand smoke refers to the smoke that come off the burning end of a cigarette or is exhaled by a smoker. Secondhand smoke contains more than 7,000 chemicals, hundreds of which are toxic and at least 70 of which cause cancer, according to the U.S. Surgeon General.
Eliminating secondhand smoke from public places, workplaces, and homes has been one of the most important public health achievements of the last century. In addition to protecting against exposure to secondhand smoke, smoke-free policies are also one of the most effective means of reducing tobacco use.