GREATER LONDON ASSEMBLY INVESTIGATIVE COMMITTEE ON SMOKING IN PUBLIC PLACES

ETS consists of two types of smoke: smoke from the burning cigarette (sidestream smoke) and smoke exhaled by active smokers (exhaled mainstream smoke). Sidestream smoke accounts for most of the tobacco smoke found in a room in which people have been smoking. Although the chemical composition of ETS differs from the smoke inhaled by active smokers, both contain a similar range of substances (over 4000 compounds) with known toxic and carcinogenic effects. The amounts of these toxic substances in the secondhand smoke are often many times the amounts that the smoker inhales.