In 2010, the U.S. Surgeon General issued the report: How Tobacco Smoke Causes Disease. The report concluded "There is no safe level of exposure to tobacco smoke. Any exposure to tobacco smoke – even an occasional cigarette or exposure to secondhand smoke – is harmful."

Secondhand smoke contains more than 7,000 chemicals and chemical compounds. At least 70 of them are known specifically to cause cancer. In 2006, the Surgeon General found that secondhand smoke is a proven cause of lung cancer, heart disease, serious respiratory illnesses such as bronchitis and asthma, low birth weight and sudden infant death syndrome. The Surgeon General also found that secondhand smoke is responsible for tens of thousands of deaths in the United States each year.

Only smoke-free air laws provide effective protection from secondhand smoke.

2014 U.S. Surgeon General's Report: The Health Consequences of Smoking-50 Years of Progress
2010 U.S. Surgeon General's Report: How Tobacco Smoke Causes Disease
2006 U.S. Surgeon General's Report: The Health Consequences of Involuntary Exposure to Tobacco Smoke
U.S. Centers for Disease Control & Prevention: Secondhand Smoke
Tobacco Free Nebraska: Secondhand Smoke