Methods to best monitor respirable silica levels
Historically, several analytical methods have been used to measure levels of respirable crystalline silica, including atomic absorption, calorimetry, gravimetry, microscopy, Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). Most of those methods became unpopular due to low sensitivity. Today, XRD and FTIR are the most sensitive methods that comply with existing norms for respirable silica analysis.
Of the two, XRD is generally considered more accurate when identifying crystalline silica quartz polymorphs, as well as when distinguishing between confounding minerals which may also be present. For example, OSHA ID-142 defines XRD as the only accurate technique to measure crystalline silica levels in various types of industrial dust. This method is similar to NIOSH Method 7500.
Our Empyrean and Aeris diffractometers can offer XRD solutions for respirable crystalline silica analysis. The Aeris is a compact XRD which can be placed next to mine sites. Thanks to its automated analysis, it provides information on respirable crystalline silica levels in just a few minutes – with no need for additional XRD expertise. The Empyrean advanced XRD platform is used by service laboratories for certification purposes.