The exposure of nonsmokers to the toxic gases released by the burning of tobacco products in their homes, workplaces, or recreational environments. Exposure to second-hand smoke has been linked to allergies, asthma, cardiovascular diseases, lung diseases, and stroke. Passive smoking causes about 30,000 deaths from heart disease and another 3,000 lung disease deaths annually in the U.S.

SYN: second-hand smoking.

SEE: tobacco.