Making Masks for the Workplace
Interim Guidance from NIOSH on New Masks Which Build Upon the ASTM International (ASTM) Standard for Face Coverings
NIOSH recommends a new standard in masks, called Workplace Performance and Workplace Performance Plus masks, for workplaces. Manufacturing masks that comply with the new NIOSH criteria can help protect people in the workplace from SARS-CoV-2, the virus that causes COVID-19. These masks cannot be used as a replacement for respiratory protection when it is needed. The new mask criteria and ASTM Specification for Barrier Face Coverings, F3502-21external icon (ASTM Standard) determine an expected level of source control performance for workers when wearing the mask according to manufacturer’s instructions.
To fully meet the new NIOSH criteria, masks must conform to all criteria stated in ASTM F3502-21 and meet additional quantitative leakage criteria. This guidance assists manufacturers with designing and producing masks that meet the criteria. These masks have an expected level of source control performance to help prevent the spread of SARS-CoV-2, the virus that causes Coronavirus Disease 2019 (COVID-19), in the workplace. The criteria incorporate the ASTM Standardexternal icon and establish design and performance requirements. The classification system in the criteria provides a standard for filtration efficiency, breathability, and leakage around and through the mask. Because the classification is specific to testing the mask and masks are not fitted to each wearer, individual performance for source control or amount of inhaled particulate matter cannot be guaranteed.
To fully meet the new NIOSH criteria, masks must conform to all of the design requirements and meet the performance criteria stated in the ASTM Standardexternal icon. They must meet additional NIOSH performance criteria and undergo testing, which are both described below. Manufacturers of these masks should provide the minimum labeling criteria and information about proper use, and have a system in place to maintain the consistency of mask quality.
The ASTM design requirements state the mask must:
- Cover the wearer’s nose and mouth and fit snugly against the sides of the face and nose without gaps, as determined by the design analysis.
- Have a means for keeping the mask over the nose and mouth for the expected period of use and range of activities.
- Have non-irritating and nontoxic materials where the mask contacts the skin.
- Be either disposable (single use) or reusable (multiple use).
- Be able to be worn by individuals with a range of fit characteristics (excluding children under age 2), or designed with multiple sizes to allow fit for a wide variety of people in the end user population.
The ASTM performance criteria address filtration and breathability. NIOSH adds criteria for leakage and labeling. The following table includes the required criteria.
|Type of Mask||Filtration||Breathability||Leakage*||Labeling|
|Workplace Performance Mask||ASTM F3502 Level 2 at ≥50%||ASTM F3502 Level 1||Leakage ratio of ≥5||MEETS WORKPLACE PERFORMANCE|
|Workplace Performance Plus Mask||ASTM F3502 Level 2 at ≥80%||ASTM F3502 Level 1||Leakage ratio of ≥10||MEETS WORKPLACE PERFORMANCE PLUS|
*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
Testing requirements for masks ensure that design and performance requirements are met. Filtration efficiency and breathability testing must be carried out by an ISO-17025 accredited laboratory following the methods in Section 8 of the ASTM Standardexternal icon. The leakage ratio requirement is determined using a modified version of the test procedure described in the ASTM Standard Test Method for Respirator Fit Capability for Negative-Pressure Half-Facepiece Particulate Respirators, F3407-20external icon.
- Filtration efficiency must be tested according to Section 8.1 of the ASTM Standardexternal icon. Masks must meet the filtration efficiency level 2 at the following filtration efficiencies:
- Workplace Performance masks: 50% or greater
- Workplace Performance Plus masks: 80% or greater
- Breathability must be tested according to Section 8.2 of the ASTM Standardexternal icon. Both Workplace Performance and Workplace Performance Plus masks must meet the breathing resistance requirements for Level 1: ≤15 mm H20
- Leakage must be tested according to the ASTM Standard Test Method for Respirator Fit Capability for Negative-Pressure Half-Facepiece Particulate Respirators, F3407-20external icon, using the modifications detailed in Section 8.3 of the ASTM Standardexternal icon. The modifications reduce the number of population-representative cells, or face sizes, required. The leakage ratio is the number of particles outside the mask compared to the number inside the mask. Masks must meet the following leakage ratios:
- Workplace Performance masks: 5 or greater
- Workplace Performance Plus masks: 10 or greater
Masks and packaging (smallest unit or package) must be labeled according to the ASTM Standardexternal icon and include the following additional wording:
- Workplace Performance masks: “MEETS WORKPLACE PERFORMANCE”
- Workplace Performance Plus masks: “MEETS WORKPLACE PERFORMANCE PLUS”
Masks need to meet all of the NIOSH criteria and ASTM Standardexternal icon criteria prior to being labeled. User instructions must be provided with the smallest saleable unit or package according to the ASTM Standardexternal icon.
A conformity assessment addresses how masks meet the ASTM Standardexternal icon. ASTM compliant mask manufacturers must:
- Apply “Model A” requirements of ASTM F3050-17, Standard Guide for Conformity Assessment of Personal Protective Clothing and Equipmentexternal icon.
- Set the frequency of testing.
- Address product quality.
- Perform filtration efficiency and airflow resistance in an ISO-17025 accredited laboratory.
Quantitative leakage testing is not subject to the conformity assessment requirement; however, it may be performed by the manufacturer. Quantitative leakage testing is a requirement for these masks, even though it is an option in the ASTM Standardexternal icon.
Manufacturers are permitted to meet more rigorous requirements for a conformity assessment (3rd party certification).
ASTM . F3502-21 Standard Specification for Barrier Face Coveringsexternal icon. West Conshohocken, PA: ASTM International.
ASTM . ASTM F3050-17 Standard Guide for Conformity Assessment of Personal Protective Clothing and Equipmentexternal icon. West Conshohocken, PA: ASTM International.
ASTM . ASTM F3407-20 Standard Test Method for Respirator Fit Capability for Negative-Pressure Half-Facepiece Particulate Respiratorsexternal icon. West Conshohocken, PA: ASTM International.
ASTM has granted free access to COVID-19 related standardsexternal icon including the new ASTM F3502-21 Standard.