Smoke that passes from a cigarette into the surrounding air, rather than into the smoker's lungs.
 asthmatics experience a significant decline in lung function when exposed to sidestream smoke
 Example sentencesExamples
-  Second-hand or passive smoke exposure occurs when nonsmokers breathe the sidestream smoke created in indoor environments from the presence of smokers.
 -  The sidestream smoke that others breathe in is actually more dangerous than the mainstream smoke that smokers inhale directly from a cigarette.
 -  Ventilation systems certainly do work in terms of removing the irritants in cigarette smoke, but they do not remove the carcinogens in sidestream smoke.
 -  Many potentially toxic gases are present in higher concentrations in sidestream smoke than in mainstream smoke and nearly 85 per cent of the smoke in a room results from sidestream smoke.
 -  There is no ventilation system that reduces or eliminates the carcinogenic products of second-hand smoke or the sidestream smoke from cigarette smoking.