The model pDR-1200 includes a particle size-selective inlet cyclone which permits size segregated measurements (i.e., PM10, PM2.5, respirable, etc.) as well as enables the user to perform aerodynamic particle sizing by varying the sampling flow rate. The model pDR-1200 incorporates, downstream of its photometric sensing stage, a standard 37-mm filter holder on which all sampled particles are collected for subsequent analysis or gravimetric referencing/calibration, if so desired.