Advanced Instrument Processing Solutions

The classification of masks and respirators is a complex subject with multiple classifications for a variety of working situations, so I am going to just focus on those that pertain to working in decontamination. Let me begin with the fact that you do not need a respirator for decontamination. Although respirators would offer you great protection from aerosolized particulates, they must be fit tested and worn properly to be effective. Furthermore, the more filtration they provide, the harder they become to breathe through. Respirators are best for use in patient rooms where respiratory isolation is indicated.

I did state that a mask for decontamination should be fluid resistant, and when searching for masks, you will see different resistance qualifications and wonder what they might refer to, so I will give some examples here to help out.

If you see BFE > 99%:
This qualification is based on testing done by the ASTM (ASTM F2101-01) for Bacterial Filtration Efficiency, the material being tested is mechanically subject to 3 micron droplets of liquid aerosol containing Staphylococcus aureus at a flow rate of 28.3 L/min, and a material of this classification is capable of filtering out more that 99% of this aerosol. (Make sure this BFE rating is based on the ASTM F2101-01 testing and not on the older Modified Greene and Vesely Test, where a human subject says the word “Chew” and “Sing” distinctly at 10 second intervals for 1 minute through the material being tested in a closed container. The container is then cultured and a bacterial count is taken but there is no specific organism counted).

If you see PFE > 95%:
This qualification is based on Submicron Particulate Filter efficiency testing done by the ASTM (ASTM F2299).This test uses 0.1micron latex spheres at a flow rate 0.5 to 25cm/s the particles are counted with a light scattering photometer before and after passing through the material being tested, so a PFE>95% would mean that more than 95% of these spheres were filtered by the test material.

NIOSH Particulate Filtration Efficiency testing for respirators, (yes I know I said you don’t need a respirator for decontamination) is much more stringent. For healthcare purposes N series respirators apply (N here = Not resistant to oil, the other two classifications are R- Resistant to oil and P-Oil Proof would include oil in their testing aerosol). The challenge here is ~0.3microns liquid sodium chloride aerosol at flow rate of 85L/minute. A collection of at least 95% of this by the material gives the respirator an N95 rating, at least 99% collection would be an N99 and anything 99.7% and over gives the material an N100 rating.(These N,R and P classifications truly only apply to respirators and not face masks)

If the masks make the claim ASTM F1862 120mmhg Fluid Resistance:
This is the actual fluid resistance of the mask based on ASTM testing. In this challenge, a high velocity stream of synthetic blood is aimed at the material being tested at different pressures (80mmHg, 120mmHg and 160mmHg) to replicate blood exiting a puncture wound at a variety of blood pressures. An 80mmHg rating would be a Low fluid barrier classification, 120mmHg would be a Medium and 160mmHg a High.

Another thing you might see is a Differential Pressure Test (Delta P or ∆P) number:
The lower the number here the more breathable the mask is but, the more breathable the mask is the less protection it offers.

Now if this is not complicated enough ASTM F2100-11 has prescribed new mask standards for fluid resistant face masks as follows:

ASTM Level 1
Low Fluid Resistance     80mmHg
Filtration Efficiency      BFE>95%
PFE>95% @ 0.1micron
Breathability-∆P             <4.0mm H2O/cm2
Flame Spread                   Class 1 (low flammability)

ASTM Level 2
Moderate Fluid Resistance 120mmHg
Filtration Efficiency       BFE>98%
PFE>98% @ 0.1micron
Breathability-∆P              <5.0mm H2O/cm2
Flame Spread                    Class1 (low flammability)

ASTM Level 3
High Fluid Resistance 160mmHg
Filtration Efficiency        BFE>98%
PFE>98% @ 0.1 micron
Breathability-∆P               <5.0mm H2O/cm2
Flame Spread                     Class 1 (low flammability)

Wow that’s a lot of information… So now the choice is yours, but if it were up to me, knowing that surgical masks truly do not provided the optimum protection that a respirator does, I would at least choose one that provided me with the most protection, like an ASTM level 3 Mask, or at least one that had all those qualities.