"Between 70% and 90% of non-smokers in the American population, children and adults, are regularly exposed to secondhand smoke. It is estimated that only 15% of cigarette smoke gets inhaled by the smoker. The remaining 85% lingers in the air for everyone to breathe. If a person spends more than two hours in a room where someone is smoking, the nonsmoker inhales the equivalent of four cigarettes." (Quoted from article)