Sidestream smoke:

According to American Lung Association of Georgia, “Sidestream smoke-which a nonsmoker inhales whenever he's around someone who's smoking actually has higher concentrations of some harmful compounds than the mainstream smoke inhaled by the smoker. Studies show that there are several cancer-causing substances, as well as more tar and nicotine, in sidestream smoke as compared to mainstream smoke, In addition, carbon monoxide, which robs the blood of oxygen, can be two to fifteen times higher in sidestream smoke. Most of the smoke in a room results from sidestream smoke. When nonsmokers breathe in this type of smoke from other people's cigarettes, cigars, and pipes, it is often called involuntary or passive smoking.”