Environmental Tobacco Smoke Particles

Abstract

IntroductionEnvironmental tobacco smoke (ETS) is a mixture of gases and particles. It is generated by the combustion of tobacco products, including cigarettes, cigars, and pipes. Most ETS issues from the smoldering tobacco between puffs. Exhaled mainstream smoke also contributes to ETS.Once released to the environment, the particles and gases in ETS are subjected to physical and chemical processes that can alter their concentrations, their physical form, and their chemical composition. For example, dispersion processes such as turbulent mixing cause ETS concentrations to become more uniformly distributed throughout a room. Deposition onto indoor surfaces reduces airborne particle concentrations and shifts the particle size distribution. Sorptive interactions with indoor materials can alter the relative amounts of volatile and semi-volatile compounds that remain airborne.Although ETS comprises both gases and particles, for the purposes of this chapter, we focus exclusively on the particle phase. ETS particles are small liquid droplets, mostly in the size range 0.02-2 µm in diameter. Chemically, they are mainly comprised of organic compounds that have vapor pressures sufficiently low to remain in the condensed phase. These compounds are formed during smoking by volatilization, pyrolysis, and partial oxidation of the components of the tobacco product. It is the scattering of light by particles that causes smoke to be visible.Environmental tobacco smoke is a major contributor to indoor air concentrations and human exposures to particles. Consequently, many studies have been concerned with the nature and significance of ETS particles. In this chapter, we summarize what has been learned, emphasizing the physical and chemical processes that influence indoor ETS particle levels. We point out several unresolved issues that warrant further study. 245 3.5 b NSH = non-smoking home; SH = smoking home; NSW = non-smoking workplace; SW = smoking workplace; NS = non-smoker; NA = not available. c PTEAM = USEPA's Particle Total Exposure Assessment Methodology. d The Harvard Six City study is described with preliminary results in Spengler et al. (1981). The six cities were: Portage, WI; Topeka, KS; Kingston-Harriman, TN; Watertown, MA; St. Louis, MO; Steubenville, OH.e The main reference for the New York State study is Sheldon et al. (1989). f The sixteen cities surveyed were: Knoxville,

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