A continuous alpha monitor includes an air intake mechanism, which in turn includes an air mover and an air flowrate monitor, an air intake prefilter that limits particulates in the air intake mechanism to an aerodynamic diameter of 10 microns or less, and a particle size detector mounted downstream of the air intake prefilter, the air particle size detector providing a distribution of aerodynamic diameters of particulates in air passing the prefilter, the particulates including depleted uranium particulates. The monitor further includes a sample filter mechanism that collects the particulates; a detector mechanism that detects alpha radiation emitted by the collected particulates; a dust loading mechanism that computes a dust thickness on the sample filter mechanism; and an output mechanism that provides an indication of alpha concentration detected by the detector mechanism.