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Report: Effects of Ultraviolet Germicidal Irradiation (UVGI) on N95 Respirators

Publication Date: 2015

The ability to disinfect and reuse disposable N95 filtering facepiece respirators (FFRs) may be needed during a pandemic of an infectious respiratory disease such as influenza. Ultraviolet germicidal irradiation (UVGI) is one possible method for respirator disinfection.

However, UV radiation degrades polymers, which presents the possibility that UVGI exposure could degrade the ability of a disposable respirator to protect the worker.

To study this, we exposed both sides of material coupons and respirator straps from four models of N95 FFRs to UVGI doses from 120–950 J/cm2. We then tested the particle penetration, flow resistance, and bursting strengths of the individual respirator coupon layers, and the breaking strength of the respirator straps.

We found that UVGI exposure led to a small increase in particle penetration (up to 1.25%) and had little effect on the flow resistance. UVGI exposure had a more pronounced effect on the strengths of the respirator materials. At the higher UVGI doses, the strength of the layers of respirator material was substantially reduced (in some cases, by >90%). The changes in the strengths of the respirator materials varied considerably among the different models of respirators. UVGI had less of an effect on the respirator straps; a dose of 2360 J/cm2 reduced the breaking strength of the straps by 20–51%.

Our results suggest that UVGI could be used to effectively disinfect disposable respirators for reuse, but the maximum number of disinfection cycles will be limited by the respirator model and the UVGI dose required to inactivate the pathogen.

The full report can be found here:

About the Mask-Sanitizer:

The Mask-Sanitizer is a Portable On-Site Face Mask Disinfection Chamber for disposable face masks. The disinfection method is eight (8) germicidal UV-C bulbs positioned in front of and behind the N95 face masks. 10 face masks can be disinfected during each 15-minute cycle. The Mask-Sanitizer can be used at hospitals, fire stations, police stations, nursing homes, etc., and can be located near the actual point of use. One or more mask-sanitizers can be located at each station, department, wing, hallway or emergency room, so there is no need to handle and disinfect mass numbers of masks at a central or off-site location. The Mask-Sanitizer is simple to operate, easy to roll around, and versatile enough to be transported in the back of a minivan or SUV.

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