Standards

The ASTM International standard for cloth masks is F3502. More information about this standard can be found in this CDC blog. Masks compliant with this standard are listed by the CDC.

Guidance from NIOSH builds on these standards and suggests thresholds for workplace masks based on fit testing methods. Masks that meet the more stringent F3502 level 2 standard, and additionally filtering at 80-89% on fit testing are designated ‘workplace performance’ and those filtering at >=90% on fit testing are designated ‘workplace performance plus’.