Effects of Organic Solvents on the Laboratory Filtration Performance of Electret N95 and P100 Filtering Facepiece Respirators
Samy Rengasamy, Benjamin C. Eimer, and Adam Miller.
CDC has predicted respirator shortage during a widespread influenza pandemic. To address this issue, research on the reuse of filtering facepiece respirators after simple biological decontamination methods was recommended. Successful reuse of filtering facepiece respirators will require decontamination methods that can inactivate microorganisms without compromising filtration performance. Isopropanol is commonly used for decontaminating many medical devices, but its concentration dependent effect on the filtration performance of filtering facepiece respirators has not been studied in detail. In this study, two models of electret N95 and two models of electret P100 filtering facepiece respirators were treated with varying concentrations of isopropanol and penetration levels for polydisperse and monodisperse NaCl aerosols were measured at 85 L/min flow rate. The results showed that submerging in liquid isopropanol increased the penetration levels of 20-400 nm size monodisperse particles for both N95 and P100 filtering facepiece respirators in a concentration dependent manner. N95 and P100 filtering facepiece respirators exceeded NIOSH allowed 5% and 0.03% penetration levels after treatment with >10% and >50% isopropanol, respectively. In other experiments, penetrations obtained for isopropanol liquid and vapor treated filtering facepiece respirators were compared with those obtained for liquid and vapor forms of xylene, an alternate solvent and cleaning agent. Both 100% isopropanol and 100% xylene treated N95 and P100 filtering facepiece respirators showed a marked increase in penetration levels for polydisperse as well as monodisperse aerosols with an associated shift in the most penetrating particle size from 50 nm to 200-300 nm range. On the contrary, isopropanol and xylene
vapors produced different effects on penetrations. Isopropanol vapor exposure dramatically increased the penetration levels for polydisperse and monodisperse aerosols with a simultaneous shift in the most penetrating particle size from 50 nm to 200-300 nm range. However, xylene vapor neither increased the penetration levels for polydisperse and monodisperse aerosols nor shifted the most penetrating particle size. These results can help in the design of future studies on the decontamination of filtering facepiece respirators contaminated with different microorganisms.
Keywords: N95 and P100 filtering facepiece respirators, decontamination, isopropanol, xylene, liquid and vapor, aerosol penetration