Respirable fraction (PM4) of crystalline silica poses significant health risks when inhaled, necessitating meticulous assessment techniques. The NIOSH 7500 and 7602 methods are well suited for the measurement of crystalline silica in industrial air and are used for quartz concentrations between 10 to 1000 μg/m³. At the same time, the procedure is not suitable for the assessment of residential or ambient (environmental) air, where the expected concentration of quartz is expected to be below 3-5 μg/m³
To address the limitations of the traditional methods, LCS Laboratory Inc. has introduced a novel approach for trace analysis of respirable crystalline silica in air. The key difference of our technique from other procedures is that the samples of airborne dust are collected as Total Suspended Particulates (EPA), Inhalable Particulates (MDHS), or Total Particulates (NIOSH, OSHA) using any high-velocity sampling pumps. The PM4 (or any other fraction) is extracted from the dust sample by our laboratory and further analyzed for silica. This approach eliminates restrictions of the size-selective sampling imposed on personnel, making the procedure simpler and enhancing applicability in scenarios where the size-selective equipment is unavailable or impractical.
The LCS method comprises three sequential stages:
Sample Collection and Submission: Clients are instructed to gather air dust samples using accepted protocols such as NIOSH 0500, MDHS 14/4, EPA IO-2.1, or comparable methods. Following sample collection, the materials are submitted to LCS Laboratory Inc. for subsequent analysis.
Air sampling cassettes
Fractionation of PM4: The subsequent step involves the extraction of PM4 fractions from the collected samples. Our laboratory follows the modified ASTM D7928 method. The dust is extracted from an air sampling cassette using sonication, and the PM4 fraction is extracted and re-collected on a different PVC filter. If necessary, PM2.5 and PM10 fractions can be also extracted from the same sample.
Crystalline Silica Quantification: The extracted PM4 fractions are analyzed employing the NIOSH 7602 method. Crystalline Quartz and Cristobalite are analyzed and reported with a sensitivity of 5 micrograms per sample. The overall sensitivity reaches under 1 microgram per cubic meter of crystalline silica when at least 5 m³ of air is collected.
Sensitivity and Compliance: The method’s sensitivity aligns with established clean air guidelines for respirable crystalline silica, ensuring regulatory compliance and accurate health risk assessment.
If you need to evaluate silica concentration in residential or ambient air, please contact us to place an order or to discuss your project. Thank you for considering LCS Laboratory as your service provider.
