The Marple Series 290 Cascade Impactor has been re-specified with development assistance from Westech Instruments. Originally a personal sampler for health and safety monitoring, the Marple 298 is now a device currently validated for use in the pharmaceutical industry. Accurate aerodynamic particle size distributions range from 0.4 to 21 microns with a nominal flowrate of 2 L/min. Cutoff diameters have been independently validated using dynamic calibration techniques.