Secondhand smoke is the combination of smoke from the burning end of a   cigarette, pipe, or cigar (sidestream smoke) and the smoke exhaled by the smoker (mainstream smoke).

While secondhand smoke has been referred to a environmental tobacco smoke (ETS)  in the past, the term “secondhand” smoke better captures the involuntary nature of exposure.

Cigarette smoke contains more than 4,000 chemical compounds.

• Secondhand smoke contains many of the same chemicals that are present in the smoke inhaled by smokers.

• Because sidestream is generated at lower temperatures and under different   conditions than mainstream smoke, it contains higher concentrations of many of the toxins found in cigarette smoke.

The National Toxicology Program estimates that at least 250 chemicals in secondhand smoke are known to be toxic or carcinogenic.

Secondhand smoke has been classified as a known human carcinogen (cancer-causing agent) by the U.S. Environmental Protection Agency, the National Toxicology Program,  and the International Agency for Research on Cancer, and an occupational Carcinogen by the National Institute for Occupational Safety and Health.

• Secondhand smoke contains more than 50 cancer-causing chemicals.

• When nonsmokers are exposed to secondhand smoke, they inhale many of the same cancer-causing chemicals that smokers inhale.

Effects of Secondhand Smoke

The 2006 U.S. Surgeon General’s report, “The Health Consequences of Involuntary Exposure to Secondhand Smoke, has concluded that:

• There is no safe level of exposure to secondhand smoke.  Breathing even a little    secondhand smoke can be dangerous.
• Secondhand smoke causes heart disease and lung cancer.
• Secondhand smoke is a known cause of low birth weight, Sudden Infant Death Syndrome (SIDS), asthma, bronchitis, pneumonia, middle ear infections, and other diseases.