Masks must have a way of being held to the face, and sizing information should be provided. ASTM F3502 requires masks be designed to fit snugly to the face, covering both the mouth and nose, and reducing gaps. Fitįor masks designs that are not focused on creating a tight seal/fit to the face (e.g., pleated medical masks), air can leak around the edges of the mask, carrying unfiltered particles in and out. Achieving a balance of these four factors is key to good mask design. Unfortunately, the materials that most effectively block droplets and particles typically have poorer breathability, fit, and usability. Assessment of fit, filtration, and breathability both before AND after maximum number washing/laundering cyclesĪs described in our “Big Four: Criteria for Fabric Mask Materials” post, breathability and filtration are both key factors in face mask design and materials selection.Filtration: NaCl Aerosol Filtration at 0.3um.Fit: Design analysis and leakage assessment.To ensure that barrier face coverings provide these functions, ASTM F3502 establishes design and performance criteria in three general areas: 1) protection, 2) comfort, and 3) reusability. Three Design and Performance Criteria for ASTM F3502 To help protect the user by providing “a degree of particulate filtration to reduce the amount of inhaled particulate matter”.
Since February of 2020, we’ve been asking for standards for masks/face coverings used by our communities.