We understand that the particulate efficiency can oftentimes be confusing with different standards based on different test methods.  For FLTR general use face masks, we follow the testing standard of ASTM F2100 Level 1.

Under ASTM F2100, there are two tests related to filtration; Bacterial penetration efficiency >= 95% and sub-micron particulate efficiency >= 95%.
Bacterial penetration efficiency is completed using particles of 3 microns +/- 0.3 microns.
Sub-micron particulate efficient is completed using particles of 0.1 microns

Testing our products to this standard ensures that we have good particulate filtration, especially for most bacteria, which range in size from 1 to 10 microns.