Characterization of respirable dust on the basis of particle constituents and sizes is increasingly of concern for evaluating exposure hazards. For high-resolution particle analysis, scanning electron microscopy with energy dispersive X-ray (SEM-EDX) can be an effective tool, though it requires particles to be deposited on a smooth substrate such as polycarbonate (PC) for optimal results. While direct sampling onto PC is possible, in many situations this is not the standard approach. For example, in coal mines, respirable dust samples have typically been collected onto poly-vinyl chloride (PVC) filters because they are intended for gravimetric or infrared spectroscopy analysis. Such fibrous substrates are not ideal for microscopy analysis, but an effective method to recover and redeposit the dust particles could render the samples suitable for the additional analysis. Here, we present a simple method and compare SEM-EDX results for paired samples analyzed directly on PC and following recovery from PVC and redeposition on PC. The results indicate that dust recovery from PVC is representative in terms of mineral constituents, although some changes in particle size distributions can be observed. Careful control of particle loading density is important for either direct-on-filter or recovered dust analysis.
