Crystalline silica analysis of filter samples was performed using X-ray diffraction in accordance with NIOSH Method 7500. The LODs for quartz, cristobalite and tridymite are 5 µg/sample, 10 µg/sample, and 10 µg/sample, respectively. The LOQs for quartz, cristobalite, and tridymite are 17 µg/sample, 33 µg/sample, and 33 µg/sample ...