Subpart Z
Yes — labs must evaluate silica samples using one of the specified methods listed in 1910.1053AppA. The appendix explicitly lists OSHA ID-142; NMAM 7500; NMAM 7602; NMAM 7603; MSHA P-2; and MSHA P-7 as acceptable procedures for analyzing respirable crystalline silica.
Employers must ensure the laboratory analyzing their respirable crystalline silica samples meets the quality and method requirements in 1910.1053(d)(5) and Appendix A. Specifically, employers must ensure the lab uses one of the approved analytical methods, is accredited to ANS/ISO/IEC 17025:2005 for crystalline silica, uses current NIST or NIST-traceable standards for calibration, and implements an internal QC program that reports analytical uncertainty.
Yes — laboratories must be accredited to ANS/ISO/IEC Standard 17025:2005 for crystalline silica analyses.
Labs must use the most current National Institute of Standards and Technology (NIST) or NIST-traceable standards for instrument calibration or calibration verification.
Appendix A requires laboratories to implement an internal quality control (QC) program that evaluates analytical uncertainty and provides employers with estimates of sampling and analytical error.
Yes — laboratories must characterize sample material by identifying polymorphs of respirable crystalline silica present. Identifying polymorphs matters because different forms (for example, quartz versus cristobalite) can affect the measurement and interpretation of exposure. The laboratory must also identify interfering compounds and make any necessary corrections to obtain an accurate analysis.
A laboratory may quantitatively analyze for crystalline silica only after confirming the sample matrix is free of uncorrectable analytical interferences or after correcting for those interferences. The lab must use a method that meets the performance specifications listed in Appendix A.
Each day that samples are analyzed the laboratory must perform instrument calibration checks with standards that bracket the sample concentrations. This ensures the instrument response is verified across the range of sample values being reported.
A laboratory must use five or more calibration standard levels to prepare calibration curves and ensure standards are distributed through the calibration range in a way that accurately reflects the underlying calibration curve.
Appendix A requires methods and instruments to be optimized so the quantitative limit of detection is no greater than 25 percent of the PEL based on the sample air volume. In other words, the LOD must be at or below 0.25 × the PEL when adjusted for the collected sample volume.
No — laboratories may not quantitatively analyze for crystalline silica if the sample matrix contains an uncorrectable analytical interference. The lab must either correct for interferences or not report a quantitative silica result.
Employers should request documentation showing the laboratory’s ANS/ISO/IEC 17025:2005 accreditation specifically covers crystalline silica analyses and that the accreditation body is compliant with ISO/IEC 17011:2004. The employer should retain copies of the accreditation scope and certificate as proof of compliance.
Employers should require the laboratory to implement and provide results from an internal QC program that evaluates analytical uncertainty and supplies estimates of sampling and analytical error; if the lab cannot provide that, the employer must select a different lab that meets 1910.1053AppA requirements.
No — Appendix A requires laboratories to use the most current NIST or NIST-traceable standards for instrument calibration or calibration verification, so employers should confirm the lab’s standards are current.
Yes — Appendix A requires methods and instruments be optimized so the limit of detection is no higher than 25 percent of the PEL based on the sample air volume, meaning labs must consider sample volume when determining and demonstrating their LOD.
A laboratory must use five or more calibration standard levels and ensure those standards are distributed through the calibration range in a manner that accurately reflects the underlying calibration curve — avoiding clustering and ensuring coverage across low, mid, and high concentrations relevant to samples.
No — for analyses required under 1910.1053(d)(5), Appendix A requires employers to ensure the laboratory is accredited to ANS/ISO/IEC 17025:2005 for crystalline silica analyses. Using a non-accredited lab would not meet the Appendix A requirements.
A laboratory should report that interferences were identified and describe the corrections made and provide uncertainty estimates that reflect those corrections so the employer can interpret the result accurately. Appendix A requires labs to identify interfering compounds, make necessary corrections, and provide estimates of analytical uncertainty.
Yes — NMAM 7500 is explicitly listed as an acceptable method in Appendix A, so a lab using NMAM 7500 meets the method requirement provided the lab also meets the accreditation, calibration, QC, and performance specifications in 1910.1053AppA.
Employers should obtain and retain:
These items are required or implied by the requirements in 1910.1053AppA and the employer responsibilities under 1910.1053(d)(5).
Appendix A requires methods and instruments be optimized so the quantitative limit of detection is no higher than 25 percent of the PEL based on sample air volume; that effectively requires labs to optimize instrument sensitivity relative to the OSHA PEL.