American Ambulance Association (AAA) issues update on N95 vs P100 masks

AAA Letter to Membership




CDC Confirmed Cases of H1N1 swine origin influenza in the U.S.
As of 1100 on May 7, 2009
Confirmed Cases= 896
Deaths= 2


Recently, confusion has emerged from the labor sector regarding the use of N95 masks versus P100 filtering face pieces in the context of the currently H1N1 flu outbreak. In response, OSHA has published a clarification. In short, N95 masks remain the recommended level of respiratory protection for pandemic influenza.

N 95 versus P 100 filtering face pieces for EMS personnel
A concern has been raised that Emergency Medical Service (EMS) personnel should be wearing P100 filtering face piece respirators (FFR) instead of N95 filtering face piece respirators as the minimum respiratory protection required during a pandemic influenza crisis. The filter efficiency of a P100 FFR is greater than that of an N95 only when the great majority of the particulates it encounters are concentrated at the most penetrating particle size of 0.3 microns.

That is where filter efficiency would have a significant impact on penetration into the respirator. Once the particle size of infectious particles and droplets encountered increase in size slightly, the efficiency of an N95 filter rapidly approaches that of the P100 filter. The distribution of particles from coughs and sneezes of pandemic flu infected individuals is not predominately in the most penetrating particle size range, and particles are readily captured by either an N95 or P100 filter.

Both the N95 FFR and the P100 FFR have the same Assigned Protection Factor (APF) of 10. The actions that most impact the level of protection that EMS personnel receive against pandemic influenza are obtaining a proper face piece fit consistently, and performing fit testing to make sure that the best fitting respirator has been selected.

It is the quality of the face piece fit that can most greatly impact the protection provided by any respirator. A P100 FFR can increase breathing resistance for the wearer and could result in increased leakage past the face seal for an improperly fitting respirator. The N95 and P100 filters have both been shown to be effective in controlling exposures to bacterial and viral particles in the atmosphere.

Therefore, OSHA has recommended the fit tested N95 filtering face piece respirator used within the context of a respiratory protection program as the minimum level of respiratory protection for pandemic flu.

Office of Emergency Management
Directorate of Technical Support and Emergency Management
US Department of Labor/OSHA
200 Constitution Are NW RM N3655
Washington, DC 20210


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