Sidestream smoke
Sidestream smoke is smoke which goes into the air directly from a burning cigarette, cigar, or smoking pipe. Sidestream smoke is the main component (around 85%) of Second-hand smoke (SHS), also known as Environmental Tobacco Smoke (ETS) or passive smoking The chemical constituents of sidestream smoke are different from those of directly inhaled ("mainstream") smoke. Sidestream smoke has been classified as a Class A carcinogen by the U.S. Environmental Protection Agency.