Environmental tobacco smoke consists of both vapor and particulate phase components. Due to the nature of vapor and particulate phases, they rarely correlate well, and an accurate assessment of ETS levels in indoor air requires determining good tracers of both phases. Among the attributes of an ideal ETS tracer, one critical characteristic is that the tracer should “remain in a fairly consistent ratio to the individual contaminant of interest or category of contaminants of interest (for example, suspended particulates) under a range of environmental conditions...” (5). Solanesol meets this requirement, staying in a constant ratio to the RSP contributed by tobacco smoke over a variety of ventilation conditions and sampling durations (6). UVPM and FPM, which are the tracers or markers employed by Test Method D5955, also fulfill this requirement. Airborne solanesol, however, is unique in that it is specific to tobacco smoke and is found only in the particulate phase of ETS. Its high molecular weight and low volatility make it extremely unlikely that any solanesol will be lost from the membrane filter used for sample collection. Solanesol constitutes approximately 3 % by weight of the RSP of ETS (2,7,8), making it suitable for measurement at realistic smoking rates. Of the available ETS particulate phase markers (UVPM, FPM, and solanesol), all are currently used and relied upon, but solanesol is considered to be a better marker for the particulate phase of ETS and, as a result, provides the best way of quantifying the contribution of ETS particulate matter to RSP (3,4,9,10,11,12,13).
To be able to quantify the contribution of ETS to RSP with a tobacco-specific marker is important because RSP is not specific to tobacco smoke. RSP is a necessary indicator of overall air quality; the Occupational Safety and Health Administration (OSHA) has previously set a PEL (permissible exposure level) for respirable dust in the workplace of 5000 μg/m3. However, RSP emanates from numerous sources (14) and has been shown to be an inappropriate tracer of ETS (7,15,16,17). UVPM and FPM are used as more selective markers to estimate the contribution of tobacco smoke to RSP; however, these markers can overestimate the contribution of tobacco smoke to RSP due to potential interference from nontobacco combustion sources. (Refer to Test Method D5955 for the protocol on determining UVPM and FPM.) Although UVPM and FPM are useful in investigations of indoor air quality, solanesol is a better indicator of the tobacco smoke contribution to RSP. This test method has been used to apportion RSP into ETS and non-ETS components by determining the weight ratio of solanesol to total RSP (2,3,4,7,18,19).
1.1 This test method covers the sampling/analysis of respirable suspended particles (RSP) and the estimation of the RSP fraction attributable to environmental tobacco smoke (ETS). The test method is based on collection of total RSP on a membrane filter, extraction of the filter in methanol, and determination of solanesol, a C45 isoprenoid alcohol, by high performance liquid chromatography (HPLC) with ultraviolet (UV) detection.
1.2 This test method is compatible with the determinations of gravimetric RSP, ultraviolet particulate matter (UVPM), and fluorescent particulate matter (FPM) (see Test Method D5955), but does not require th......
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