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. 2015;12(8):509-17.
doi: 10.1080/15459624.2015.1018518.

Effects of Ultraviolet Germicidal Irradiation (UVGI) on N95 Respirator Filtration Performance and Structural Integrity

William G Lindsley  1 , Stephen B Martin Jr, Robert E Thewlis, Khachatur Sarkisian, Julian O Nwoko, Kenneth R Mead, John D Noti
Affiliations

Effects of Ultraviolet Germicidal Irradiation (UVGI) on N95 Respirator Filtration Performance and Structural Integrity

William G Lindsley et al. J Occup Environ Hyg. 2015.

Abstract

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/cm(2). 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/cm(2) 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.

Keywords: airborne transmission; disinfection; healthcare workers; respiratory infections/prevention; respiratory protective devices; ultraviolet light.

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Figures

Figure 1
Figure 1. Particle penetration vs. UVGI exposure for respirator material. (A) 3M 1860; (B) 3M 9210; (C) GE 1730; (D) KC 46727. Each pair of bars shows the mean penetration for four 37 mm test coupons before and after UVGI exposure. Error bars show the standard deviation.
Figure 2
Figure 2. Flow resistance vs. UVGI dose for respirator material. (A) 3M 1860; (B) 3M 9210; (C) GE 1730; (D) KC 46727. Each pair of bars shows the mean flow resistance for four 37 mm test coupons before and after UVGI exposure. The units “mm H2O” are used by convention; 1 mm H2O = 9.8 N/m2. Error bars show the standard deviation.
Figure 3
Figure 3. Bursting strength vs. UVGI dose for respirator material. (A) 3M 1860; (B) 3M 9210; (C) GE 1730; (D) KC 46727. Each data point shows the mean bursting strength for four 37 mm test coupons exposed to the dose of UVGI. Error bars show the standard deviation.
Figure 4
Figure 4. Breaking strength vs. UVGI dose for respirator straps. Each data point shows the mean breaking strength for the respirator straps exposed to the dose of UVGI. Eight straps were tested at 4 different doses, with a matched control tested for each exposed strap (32 controls total). Error bars show the standard deviation.
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References

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