Environmental tobacco smoke (ETS) has been analyzed with respect to several components following smoking of research cigarettes in an experimental chamber. Parameters analyzed and their airborne yeild per cigarette included: particulate matter (10 mg) and its mutagenic activity in a Salmonella bioassay, carbon monoxide (67 mg), nitrogen oxides (2 mg), nicotine (0.8-3.3 mg), formaldehyde (2 mg), acetaldehyde (2.4 mg), acrolein (0.56 mg), benzene (0.5 mg) and several unsaturated aliphatic hydrocarbons (e.g., 1,3-butadiene) of which isoprene (3.1 mg) had the highest yeild. ETS from commercial cigarettes were likewise analyzed in the experimental chamber and at a public location. The relative component composition is similar for the research and commercial cigarettes. All components analyzed were present at concentrations above the background concentrations. Isoprene might be utilized as a tobacco smoke tracer for unsaturated aliphatic hydrocarbons. (Copyright (c) 1989 American Chemical Society.)