Making Masks for the Workplace

Interim Guidance from NIOSH on New Masks Which Build Upon the ASTM International (ASTM) Standard for Face Coverings

New Masks for Workplaces

NIOSH provides new performance recommendations for masks used in the workplace, called Workplace Performance and Workplace Performance Plus masks. Masks meeting these performance recommendations can help protect people in the workplace from SARS-CoV-2, the virus that causes COVID-19. It’s important to note that these masks cannot replace NIOSH-approved respirators within a workplace respiratory protection program. The new performance recommendations and ASTM Specification for Barrier Face Coverings, F3502-21 (ASTM Standard) determine a source control level. Workers wearing the mask according to manufacturer’s instructions can expect a level of source control performance.

What Manufacturers Need to Know

To fully meet the new NIOSH performance recommendations, masks must conform to all criteria stated in ASTM F3502-21. In addition, they must meet certain quantitative leakage performance recommendations. This guidance assists manufacturers with designing and producing masks that meet the performance recommendations. These masks have an expected level of source control performance to help prevent the spread of SARS-CoV-2 in the workplace. The NIOSH performance recommendations incorporate the ASTM Standard and establish design and performance guidance. The criteria’s classification system provides a standard for filtration efficiency, breathability, and leakage around and through the mask. The classification is specific to testing the mask, not to the fit of each wearer. Therefore individual performance for source control or amount of inhaled particulate matter cannot be guaranteed.

Design, Performance, Testing, and Labeling

To fully meet the new NIOSH performance recommendations, masks must:

  • Conform to all the design requirements.
  • Meet the performance criteria stated in the ASTM Standard.

They must also meet additional NIOSH performance recommendations and undergo testing, which are both described below. Manufacturers of these masks should provide the minimum labeling criteria and information about proper use. Additionally, they should 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.
  • 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. This includes during the expected duration 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 allow individuals with a range of fit characteristics (excluding children under age 2) wear it. 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 recommendations for leakage and labeling. The following table includes the recommended performance.

Table. Mask recommendations
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. This indicates products provide better source control across users with a variety of facial sizes.


Testing requirements for masks helps ensure that they meet design and performance requirements. An ISO-17025 accredited laboratory must carry out the filtration efficiency and breathability testing.  The accredited laboratory needs to follow the methods in Section 8 of the ASTM Standard. A modified version of the test procedure in the ASTM standard determines the leakage ratio requirement. The ASTM Standard Test Method for Respirator Fit Capability for Negative-Pressure Half-Facepiece Particulate Respirators, F3407-20 describes the test procedure.

Test Procedures
  1. Filtration efficiency
    Manufacturers must test masks according to Section 8.1 of the ASTM Standard. 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
  2. Breathability 
    Manufacturers must test masks according to Section 8.2 of the ASTM Standard. Workplace Performance and Workplace Performance Plus masks must meet the breathing resistance requirements for Level 1: ≤15 mm H20.
  3. Leakage
    Manufacturers must test masks according to ASTM F3407-20 Standard, using the modifications detailed in Section 8.3 of the ASTM Standard. 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

Manufacturers must label masks and packaging (smallest unit or package) according to the ASTM Standard. The masks and packaging must 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 performance recommendations and ASTM Standard criteria before manufacturers can label them. Manufacturers must provide user instructions with the smallest saleable unit or package according to the ASTM Standard.

Conformity Assessment

A conformity assessment addresses how masks meet the ASTM Standard. ASTM compliant mask manufacturers must:

Quantitative leakage testing is not subject to the conformity assessment requirement. However, a manufacturer may choose to perform the testing. Quantitative leakage testing is a requirement for these masks, even though it is an option in the ASTM Standard.

The ASTM Standard permits manufacturers to meet more rigorous requirements for a conformity assessment (3rd party certification).