OSHA requirements are set by statute, standards and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at https://www.osha.gov.

April 19, 2023

The Honorable Timothy M. Kaine
United States Senate
Washington, DC 20510

Dear Senator Kaine:

This is in response to your correspondence concerning your constituent, Kenneth T. White.
Mr. White requested your assistance about wiping sampling cassettes. Your correspondence was forwarded to the Occupational Safety and Health Administration (OSHA) for response.

OSHA's Salt Lake Technical Center (SLTC) is responsible for the development of sampling and analytical methods for the analysis of samples taken in support of OSHA's federal enforcement activities. OSHA Sampling and Analytical Methods are developed under SLTC's ISO-17025 quality system and laboratory accreditation, are viewed as the industry standard in quality, and are referenced and used by many industrial hygiene laboratories (both public and private) under their quality systems. OSHA's Validation Guidelines for Air Sampling Methods Utilizing Chromatographic Analysis1 and the Evaluation Guidelines for Air Sampling Methods Utilizing Spectroscopic Analysis2 are published on the OSHA website.

OSHA guidelines reference validation tests for wall deposits and are included in the sampling and analytical methods that are developed from these guidelines. Any laboratory that is citing OSHA methods should follow the method as written, or report that the method was modified and spell out the modifications clearly when providing analytical results. Modification to methods would include the not accounting for wall deposits.

Any laboratory not including wall deposits in their analysis of samples could possibly be under reporting worker exposure to the materials being sampled. OSHA would also concur that laboratories should employ sampling and analytical methods that would include procedures to capture wall deposits in their analyses or qualify results as a potential underestimation of exposure to their clients.

To meet OSHA's requirements in 29 CFR 1910.1020(c)(5)(i) for employee exposure records, which calls for inclusion of "background data relevant to interpretation of the results obtained," any deviation from accepted sampling and analytical methods, including not accounting for wall deposits, constitutes relevant exposure information and should be included in the employee exposure record.

Thank you for your interest in worker safety and health.



Douglas L. Parker

1 https://www.osha.gov/sites/default/files/methods/chromguide.pdf
2 https://www.osha.gov/sites/default/files/methods/spectroguide.pdf