Sizing of atmospheric particulates with a high volume cascade impactor

This article describes the development of a high volume cascade impactor with a sampling rate of 20 ft³/min that can be powered by high volume blowers in common use for air sampling. With this impactor it is now possible to collect enough sample of atmospheric particulates in a 24 hour period to conveniently determine an aerodynamic size distribution of suspended particulates by gravimetric analysis. The impactor has four stages and an after-filter and separates particles from the air stream by inertial impaction. The effective cutoff diameters for the stages are 7.0, 3.3, 2.0, and 1.1 microns. The after-filter traps the submicron material.