Tracers for assessing exposure to environmental tobacco smoke: what are they tracing?

The effectiveness of various tracers for measurements of exposure to environmental tobacco smoke (ETS) as a complex chemical mixture is based on the physicochemical properties of four major organic components and their dynamic behavior in indoor environments. For the particulate matter (PM) component and the very volatile organic compounds, emission and ventilation rates are generally the most important processes controlling indoor concentrations and exposures of nonsmokers. For the volatile organic compounds (VOCs) and semivolatile organic compounds (SVOCs), sorption on and desorption from indoor surfaces are additional processes that influence exposures. Laboratory and modeling studies of the dynamic behavior of nicotine, an SVOC, and PM indicate that nicotine can be used to estimate PM exposures from ETS in indoor environments when certain criteria are met: (italic>a(/italic>) smoking occurs regularly in the environment, (italic>b(/italic>) the system is near quasi-steady state, and (italic>c(/italic>) sampling time is longer than the characteristic times for removal processes. Measurements in residential and workplace buildings also support the use of nicotine as a tracer for PM in ETS. Recent laboratory and field data indicate that the VOCs from ETS can be traced using compounds with similar physicochemical properties, such as 3-ethenylpyridine, pyrrole, or pyridine. The effectiveness of nicotine for estimating exposures to the VOCs and SVOCs has not been determined, although these constitute major mass fractions of ETS.