ASTM F3502 Standard

ASTM F3502 Barrier Face Masks

F3502 barrier face coverings are uniquely designed to protect against aerosols, not just airborne droplets.

ASTM F3502-21 is the only standard recognized by the CDC for reusable fabric masks. To meet the F3502 requirement for barrier face coverings, masks must be laboratory tested to achieve significant levels of fine-aerosol filtration as well as achieving a breathability level suitable for everyday use.

Unlike surgical scrubs, an F3502 mask is designed to block aerosols, not just airborne droplets. ASTM F3502 masks are evaluated under similar test conditions as respirators like the KN95, N95 and KN94, rather than the less intensive methods used for medical procedure masks and typical fabric masks.

Here's what you should know...
  • Our Essential masks are tested without the optional filter to ensure they meet the ASTM F3502 requirements on their own, but they also contain a filter pocket for those times when you need additional filtration performance. Adding a filter brings the filtration to 98%!

  • In addition to performance testing, F3502 masks undergo a mandatory design analysis. The F3502 must fit snugly, with minimal gaps between the mask's edge and the wearer's face.

  • Puraka's ASTM F3502 masks are only sold on the Puraka Website. Carefully vet any claims of F3502-level performance from any source that does not include an F3502-compliant label and test results.

  • 3502 face coverings and medical-grade respirators like the N95 or KN95 are both tested to the same testing procedures for sub-micron filtration and breathability. Medical respirators must meet a higher filtration ratio, whereas F3502 masks must achieve higher overall breathability levels.

  • The combination of coverage, best-in-class filtration and superior breathability makes barrier face coverings the ideal solution to serve as universal source control in an office or classroom setting.

  • Because the fabric masks measured by F3502 tend to have more human touches (and associated variation) than machine-produced disposable masks, the test procedures require a large number of samples... 20 in total!

  • The performance rating for both categories is equal to the lowest-scoring mask among all the samples, which are made up of 10 new masks, and 10 masks that have been washed multiple times in order to simulate real-world use. This ensures the filtration and breathability scores cited by the CDC on its F3502 page are accurate representations of the BFC's performance over time.