Aerosol Instrumentation

Airborne particles in the size range from 1 nm to 100 μm are of interest in aerosol research and applications. Instruments are needed to characterize the physical and chemical properties of particles in the size range of interest. Both aerosol sampling and direct-reading instruments are available for the characterization tasks. For aerosol sampling instruments, particles are required to be collected in the samplers followed by off-line characterization or analytic chemical instruments. The particle collection in these instruments is typically accomplished by the inertial impaction, filtration, electrostatic precipitation or Brownian diffusion techniques. Direcr-teading instruments are capable of real time measurement. The fast response of direct-reading instruments makes it possible to follow rapid changes in both particle size and concentration, and to obtain good counting statistics. These instruments usually rely on real-time sensing techniques without sample collection, thus requiring much effort on instrument calibration. This chapter describes the basic operational principles and configurations of various aerosol instruments widely used in aerosol research and applications. The limits of using these aerosol instruments are also discussed.