Sampling of Aerosols
Sampling for aerosols is done to identify and quantify the airborne particles in an environment. As in the case of sampling for gases and vapors, the reasons for obtaining a sample may be to assess compliance with an occupational exposure limit (OEL), to assess the health risk posed by the pollutant, to determine the efficacy of control measures, to minimize exposures, or for an epidemiological study. Aerosol concentrations can be expressed as the mass of aerosol particles per unit volume of the air in which it is dispersed, e.g.,
. Other metrics can include the number of particles per unit volume of air (e.g., particles per cubic centimeter, ppcc) or the surface area of particles per unit volume of air (e.g.,
). Chapter 11 laid out the rationale for sampling size-selective, health-relevant aerosol
fractions. Although much of this chapter will focus on the practical elements of sampling systems for aerosols, we should also be concerned with the duration and frequency of sampling for exposure assessment. For some aerosols, the health effects of exposures, even for short time periods, can be acute and rapid, and thus sampling should be for short durations. Other aerosols may cause health effects that become manifest after a long time and are chronic in nature, and in such instances sampling should be of longer duration (e.g., the traditional 8-h time-weighted average).