Aerosol Measurement: Principles, Techniques, and Applications. Second Edition, PA Baron, K Willeke, eds., New York: John Wiley and Sons, Inc., 2001 Sep; :627-666
Most knowledge concerning aerosol properties has been obtained by experimental means using aerosol instruments. These instruments can be categorized as (1) collection devices such as cascade impactors, Aitken-type condensation nuclei counters, or filter samplers, which are designed to remove particles from gas streams to obtain samples for analysis; and (2) real-time, direct-reading instruments, such as an optical particle counter, photoelectric condensation nuclei counter, or a photometer. Ideally, instrument response can be theoretically computed based on equations and procedures described in the previous chapters. However, practical considerations, such as compactness, portability of the instrument, and convenience of operation, may influence the design of the instrument. Theoretical prediction of instrument response based on ideal conditions may not be fulfilled. For example, although 50% effective cutoff diameters and collection efficiencies for an impactor stage can be computed, the phenomena of particle bounce, re-entrainment, electrostatic charge effects, and wall losses can modify performance (Rao and Whitby, 1978; Cheng and Yeh, 1979). Therefore, experimental calibration is essential.