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Second-hand smoke

Second-hand smoke is a mixture of smoke from the burning end of a cigarette, pipe or cigar, and the smoke exhaled from the lungs of smokers. It is involuntarily inhaled, lingers in the air hours after cigarettes have been extinguished, and may cause a wide range of adverse health effects, including cancer, respiratory infections, and asthma.

Studies have shown that exposure to second-hand smoke causes harmful effects on the cardiovascular system and is associated with prevalent heart failure among non-smokers. Non-smokers who are exposed to second-hand smoke at home or work are thought, due to a wide variety of statistical studies, to increase their heart disease risk by 25–30% and their lung cancer risk by 20–30%. According to the World Health Organization, second-hand smoke is reported to kill about 1 million people per year and causes numerous diseases including cancer and heart diseases.

The current US Surgeon General's Report concludes that there is no established risk-free level of exposure to second-hand smoke. Short exposures to second-hand smoke are believed to cause blood platelets to become stickier, damage the lining of blood vessels, decrease coronary flow velocity reserves, and reduce heart rate variability, potentially increasing the mortality of heart attacks. New research indicates that private research conducted by cigarette company Philip Morris in the 1980s showed that second-hand smoke was toxic, yet the company suppressed the finding during the next two decades.