N95 and P100 Respirator Filter Efficiency Under High Constant and Cyclic Flow

Abstract

This study investigated the effect of high flow conditions on aerosol penetration and the relationship between penetration at constant and cyclic flow conditions. National Institute for Occupational Safety and Health (NIOSH)-approved N95 and P100 filtering facepiece respirators and cartridges were challenged with inert solid and oil aerosols. A combination of monodisperse aerosol and size-specific aerosol measurement equipment allowed count-based penetration measurement of particles with nominal diameters ranging from 0.02 to 2.9 microm. Three constant flow conditions (85, 270, and 360 L/min) were selected to match the minute, inhalation mean, and inhalation peak flows of the four cyclic flow conditions (40, 85, 115, and 135 L/min) tested. As expected, penetration was found to increase under increased constant and cyclic flow conditions. The most penetrating particle size (MPPS) generally ranged from 0.05 to 0.2 microm for P100 filters and was approximately 0.05 microm for N95 filters. Although penetration increased at the high flow conditions, the MPPS was relatively unaffected by flow. Of the constant flows tested, the flows equivalent to cyclic inhalation mean and peak flows best approximated the penetration measurements of the corresponding cyclic flows.

Evaluation of N95 Filtering Facepiece Respirators Challenged with Engineered Nanoparticles

“…For both respirators in their original condition, the MPPS using NaCl test aerosol was around 40 nm, which is similar to the 40 to100 nm range reported by other investigators for similar respirator filters and experimental conditions (Martin and Moyer, 2000;Balazy et al, 2006;Huang et al, 2007, Eshbaugh et al, 2009Renagasamy et al, 2009). After treatment with isopropanol, the MPPS for both respirators increased to 154 nm.…”

“…The 30 L min -1 was selected to represent low to moderate workload; 85 L min -1 is used for NIOSH respirator filter certification tests and represents a moderate to high workload; 130 L min -1 represents inhalation at a very heavy workload. It is also represents the peak inspiratory flow of a cyclic flow with a mean inspiratory flow of 85 L min -1 (Eshbaugh et al, 2009). Aerosol concentrations were measured with a scanning mobility particle sizer (SMPS, GRIMM Aerosol Technologies, Douglasville, GA).…”

Airflow resistance and bio-filtering performance of carbon nanotube filters and current facepiece respirators

“…2, increasing flow rate resulted in decreased absolute protection efficiencies (E AP ) for all N95 types tested (ANOVA tests; p-value: 0.050 for N95-9010, 0.000 for N95-9031 and 0.041 for N95-9042) and other FFRs (all p-values o0.05). Other studies also found penetration of submicron aerosols increased under high cyclic and constant flow conditions (Eshbaugh et al, 2008;Hofacre et al, 2006).…”

“…The existence of the leak may be the main reason, and large particles penetrated into the manikin not from the respirators, but from the leak. Numerous studies have shown that the most penetrating particles for N95 respirators are submicron particles (Weber et al, 1993;Eshbaugh et al, 2008). Unfortunately, the lower detection limit of UV-APS is 0.37 mm and it fails to offer detailed information for particles smaller than 0.37 μm including single viruses.…”

Efficiency of Respirator Filter Media against Diesel Particulate Matter: A Comparison Study Using Two Diesel Particulate Sources

“…An increase in flow rate corresponded to an increase in filter penetration in various studies (Eshbaugh et al 2009;Eninger et al 2008;Balazy et al 2006), hence penetration reported in the Janssen and Penconek studies would potentially be lower than penetration measured if the study was conducted at the standard specified flow rates.…”