X-ray diffraction (XRD) analysis is a laboratory method used to identify and measure crystalline silica in workplace air and bulk samples.
A laboratory technique that identifies crystalline materials by measuring how X-rays scatter off their atomic structure. In occupational health, XRD is a primary method for quantifying respirable crystalline silica — including quartz and cristobalite — in air samples collected from workers, and it is the basis of established methods such as OSHA ID-142 and NIOSH 7500.
A concrete contractor sends personal air samples collected during a day of cutting and grinding to an accredited lab, where XRD analysis determines each worker's respirable crystalline silica exposure for comparison with the OSHA permissible exposure limit.
Weighing a sample only shows total dust mass, while XRD identifies the crystalline silica specifically and distinguishes between its forms, which is necessary because exposure limits apply to crystalline silica rather than all dust.
OSHA's respirable crystalline silica standards require that exposure samples be analyzed by a laboratory meeting specific quality and analytical requirements, and using an accredited lab is the standard way to meet them.
Yes, XRD is also used on bulk samples of sand, rock, or products to determine their crystalline silica content, which helps employers anticipate where silica exposure risks may exist.
Part of SafetyIQ's EHS glossary: plain-English definitions of workplace health and safety terms.
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