COVID-19, Personal Protective Equipment

NIOSH Issues Nonregulatory Mask Criteria

The National Institute for Occupational Safety and Health (NIOSH) released new criteria for masks to help protect workers from the SARS-CoV-2 virus, which causes COVID-19. The NIOSH criteria incorporate the nonregulatory American Society for Testing and Materials (ASTM) Specification for Barrier Face Coverings (F3502-21).


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Masks that meet NIOSH’s new Workplace Performance Mask and Workplace Performance Plus Mask criteria are not replacements or substitutes for respiratory protection. Neither the ASTM standard nor the new NIOSH criteria require user fit testing, so a mask’s performance for source control and the amount of inhaled particles cannot be guaranteed.

In February, ASTM’s F23 committee on personal protective clothing and equipment (PPE) released a nonregulatory standard for barrier face coverings to curtail COVID-19 infections. However, face coverings certified under the F3502 specification are not intended for use as medical procedure masks for source control or respirators for worker protection.

Under the new NIOSH criteria, masks must conform to the design requirements and meet the performance criteria of the ASTM specification. They also must meet additional NIOSH performance criteria and undergo testing for mask leakage. The ASTM performance criteria address filtration and breathability. The NIOSH criteria address leakage and labeling.

Workplace Performance masks must meet the filtration criterion of F3502’s Level 2 at ≥50%, the Level 1 breathability criterion, plus a leakage ratio of ≥5. (A higher leakage ratio number means that fewer particles escape around the edges, indicating products provide better source control.) The masks must be labeled “MEETS WORKPLACE PERFORMANCE” in addition to the F3502 labeling requirements.

Workplace Performance Plus masks must meet the filtration criterion of F3502’s Level 2 at ≥80%, the Level 1 breathability criterion, plus a leakage ratio of ≥10. The masks must be labeled “MEETS WORKPLACE PERFORMANCE PLUS” in addition to the F3502 labeling requirements.

Manufacturers seeking approval to include an F3502 label on their products must supply a certified testing laboratory with 10 specimens.

Filtration efficiency and breathability testing must be performed by an International Organization for Standardization (ISO)-17025-accredited laboratory following the methods in Section 8 of the F3502 standard. The leakage ratio requirement under the NIOSH criteria is determined using a modified version of the test procedure specified in the ASTM Standard Test Method for Respirator Fit Capability for Negative-Pressure Half-Facepiece Particulate Respirators, F3407-20.

Free access to COVID-19-related standards, including the ASTM F3502-21 Barrier Face Coverings Standard, is available from ASTM.

NIOSH’s parent agency, the Centers for Disease Control and Prevention (CDC), issued new recommendations on May 13 that fully vaccinated people no longer need to wear a mask or maintain physical distance from others in any indoor or outdoor setting except where required by federal, state, local, tribal, or territorial laws, rules, and regulations or business or employer policy.

ASTM acknowledged in February that the COVID-19 pandemic has presented challenges for standards-setting organizations like ASTM and in PPE product quality. PPE quality challenges have included a lack of nonregulatory standards and certification capacity in the initial months of the pandemic, new environments and uses for PPE, and the reuse of single-use PPE due to respirator shortages.


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