Medical face mask materials covered under these specifications shall be designated as one or more of the following performance classes based on the barrier performance properties of the materials used in medical face masks:
A. Fluid resistance:
1. Fluid resistance is the mask's resistance to penetration by synthetic blood under pressure(mmhg).
2. Fluid resistance measures the ability of a face mask's material construction to minimize fluids from traveling through the material and potentially coming into contact with the clincian.
3. The higher the fluid resistance,The better the protection from exposure to blood and splash /spray/ spatter.
4. When masks become saturated with fluids from both the inside and outside,the transfer of substances through. The mask (also called wicking)is enhanced.
B. PFE Sub-Micron Particulate Filtration Efficiency:
1. PFE is the percentage of particles filtered out at a spore size of 0.1-1.0 microns.
2. PFE is the measure of the efficiency of the mask filtering of particles passing through the mask.
3. It is critical to note the size of the particles filtered.
C. BFE Bacterial Filtration Efficiency:
1. BFE is the percentage of bacteria filtered out at a spore size of 1-5 microns.
2. BFE is the measure of the efficiency of the mask filtering of bacteria passing through the mask.
D. Delta P Differential Pressure:
1. Delta P represents the pressure drop across the mask of resistance to air flow in mmh2o /m2 .
2. Delta P determines breathing resistance.
3. The higher the Delta P ,the less the breathablilty,but the better the filtration.