More than 126 million children and adults are estimated to be exposed to secondhand smoke each year, according to the recently released Surgeon General’s report, The Health Consequences of Involuntary Exposure to Tobacco Smoke.

Secondhand smoke, also known as environmental tobacco smoke, is a combination of the smoke given off by the burning end of tobacco products and the smoke exhaled by smokers.

The extent of secondhand smoke exposure varies across the country, with homes and workplaces the predominant locations for exposure. Despite recent substantial decreases, exposure to secondhand smoke remains a serious health hazard.

According to the report, scientific evidence support the following major conclusions about the causal relationship between secondhand smoke exposure and health.

• There is no risk-free level of exposure to secondhand smoke.
• Secondhand smoke causes premature death and disease in children and in adults who do not smoke.
• Children exposed to secondhand smoke are at an increased risk for sudden infant death syndrome (SIDS), acute respiratory infections, ear problems, and more severe asthma.
• Smoking by parents causes respiratory illnesses and slows lung growth in their children.
• Exposure of adults to secondhand smoke has immediate adverse effects on the cardiovascular system. For example, exposure to secondhand smoke increases the risk of coronary heart disease by 25% to 30%.
• Exposure to secondhand smoke is linked to an increased risk for lung cancer among nonsmokers. For example, nonsmokers living with a smoker have a 20% to 30% increase in the risk of lung cancer from secondhand smoke exposure.

The report also concludes that since ''separating smokers from nonsmokers, cleaning the air, and ventilating buildings cannot eliminate exposures of nonsmokers to secondhand smoke,'' eliminating smoking in indoor spaces is the only way to fully protect nonsmokers from exposure to secondhand smoke.

For details, including data charts, source information and caveats, download the PDF file at www.cesar.umd.edu/cesar/cesarfax/vol15/15-34.pdf.

Reprinted from CESAR Fax, a weekly, one-page overview of timely substance abuse trends or issues, from The Center on Substance Abuse Research (CESAR) at the University of Maryland.