A method to determine the available UV-C dose for the decontamination of filtering facepiece respirators.
OBJECTIVE
To develop a method to assess model-specific parameters for ultraviolet-C (UV-C, 254 nm) decontamination of filtering facepiece respirators (FFRs).


RESULTS
UV-C transmittance was quantified for the distinct composite layers of six N95 FFR models and used to calculate model-specific α-values, the percentage of the surface UV-C irradiance available for the internal filtering medium (IFM). Circular coupons, excised from the FFRs, were exposed to aerosolized particles containing MS2 coliphage and treated with IFM-specific UV-C doses ranging from 38 to 4707 J m(-2). Models exposed to a minimum IFM dose of 1000 J m(-2) demonstrated at least a 3 log reduction (LR) in viable MS2. Model-specific exposure times to achieve this IFM dose ranged from 2 to 266 min.


CONCLUSIONS
UV-C transmits into and through FFR materials. LR of MS2 was a function of model-specific IFM UV-C doses.


CONCLUSIONS
Filtering facepiece respirators are in high demand during infectious disease outbreaks, potentially leading to supply shortages. Reuse of disposable FFRs after decontamination has been discussed as a possible remediation strategy, but to date lacks supporting scientific evidence. The methods described here can be used to assess the likelihood that UV-C decontamination will be successful for specific FFR models.
National Institute for Occupational Safety and Health, National Personal Protective, Technology Laboratory, Pittsburgh, PA 15236, USA.
E M
EM
Fisher
R E
RE
Shaffer
D003666:Decontamination / Q000379:methods*; D005374:Filtration; D017909:Levivirus / Q000528:radiation effects; D011829:Radiation Dosage; D012134:Respiratory Protective Devices / Q000821:virology*; D014466:Ultraviolet Rays