June 3, 2021

New NIOSH Mask Guidance Builds Upon ASTM Standard for Face Coverings

New interim guidance published by NIOSH describes agency criteria for manufacturing masks to help protect workers from SARS-CoV-2. The new guidance is intended to assist manufacturers with designing and producing masks that meet the criteria, which comprises all requirements described in ASTM F3502-21, Standard Specification for Barrier Face Coverings, as well as additional quantitative leakage and labeling criteria from NIOSH. According to the agency, masks that fully meet the new criteria have an expected level of source control performance to help prevent the spread of SARS-CoV-2 in the workplace.

NIOSH’s new topic page on masks for workplaces describes criteria for the design, performance, testing, and labeling of “Workplace Performance” and “Workplace Performance Plus” masks. The filtration efficiency for both types of masks must be tested according to ASTM F3502-21 and meet the standard’s filtration efficiency level 2. Workplace Performance masks must meet filtration efficiency level 2 at efficiencies of 50 percent or greater, while Workplace Performance Plus masks must have filtration efficiencies of 80 percent or greater. Breathability criteria for both types of masks is the same, while leakage criteria differs: Workplace Performance Plus masks must have a higher leakage ratio (10 or greater) than Workplace Performance masks (5 or greater). NIOSH explains that “a higher leakage ratio number means that fewer particles escape around the edges, indicating products provide better source control across users with a variety of facial sizes.” The leakage ratio refers to the number of particles outside the mask compared to the number inside the mask.

NIOSH stresses that Workplace Performance and Workplace Performance Plus masks cannot be used to replace respiratory protection. The agency also notes that individual performance for source control and the amount of inhaled particulate matter cannot be guaranteed. This is because the classification is specific to testing the mask and masks are not fitted to each wearer.

NIOSH’s full interim guidance is available from its website. ASTM International is allowing free access to its standards related to COVID-19, including the new ASTM F3502-21 standard. A news article published in February provides additional information on ASTM F3502-21.