Face coverings are important tools used to battle the spread of infection. Until now, there have not been any standards for how they are to be constructed or their efficacy measured.
This has now changed due to release of a new standard by ASTM International, an organization that creates voluntary performance standards for a variety of products. The new standard, ASTM F3502-21 Standard Specification for Barrier Face Coverings, is the first voluntary standard directed at face coverings and is intended to apply to the general public and workers. The standard addresses design and general construction criteria, particle filtration efficiency levels, sizing and fit testing criteria, labeling instructions, specific requirements for reusable barrier face coverings, and guidance on cleaning and recommended periods of use.
The standard requires that face coverings should be made with “non-irritating” and “non-toxic” materials and should not pose a flammability hazard and has use/care instruction requirements. Product packaging will include identify the manufacturer and materials used to construct the product, and if product packaging will also include re-use and cleaning instructions. Written instructions will provide information on sizing, how to put on and take off the covering, and how to determine when the face covering should be replaced.
The standard has two classifications:
- Level 1 certified masks will have to show they can filter out at least 20 percent of particles smaller than a micron, which is roughly the size of the respiratory droplets that generally carry the coronavirus. The air flow resistance needs to be less than or equal to 15 millimeters of water column.
- Level 2 ASTM-certified masks will have to show that they filter out at least 50 percent of these particles. The air flow resistance needs to be less than or equal to 5 millimeters of water column.
Higher filtration efficiency indicates that fewer particles pass through the product. Air flow resistance testing measures the air permeability and is more of a comfort factor than a performance factor. A lower value means a more breathable and comfortable product.
To meet the standard, masks must be tested by an independent third-party lab. The products that meet the standard can state that they are certified as ASTM-compliant and can be labeled as “MEETS ASTM F3502” and with the applicable level it meets for filtration and air flow resistance.
The standard only mandates the filtration and air flow resistance tests, but it also has optional testing for inward leakage and bacterial filtration. This standard is separate from the NIOSH respirator standards for N95, N99, and N100 respirators and the ASTM standard requirements for medical face masks. While the new standard ASTM-certified masks will filter out far less than an N95 respirator, it will provide an important baseline for those who are purchasing face coverings.