Germicidal Ultraviolet Light Does Not Damage or Impede Performance of N95 Masks Upon Multiple Uses

The COVID-19 pandemic is increasing the need for personal protective equipment (PPE) worldwide, including the demand for facial masks used by healthcare workers. Disinfecting and reusing these masks may offer benefits in the short term to meet urgent demand. Germicidal ultraviolet light provides a nonchemical, easily deployable technology capable of achieving inactivation of H1N1 virus on masks. Working with N95-rated masks and nonrated surgical masks, we demonstrated that neither 254 nor 265 nm UV-C irradiation at 1 and 10 J/cm² had adverse effects on the masks' ability to remove aerosolized virus-sized particles. Additional testing showed no change in polymer structure, morphology, or surface hydrophobicity for multiple layers in the masks and no change in pressure drop or tensile strength of the mask materials. Results were similar when applying 254 nm low-pressure UV lamps and 265 nm light-emitting diodes. On the basis of the input from healthcare workers and our findings, a treatment system and operational manual were prepared to enable treatment and reuse of N95 facial masks. Knowledge gained during this study can inform techno-economic analyses for treating and reusing masks or lifecycle assessments of options to reduce the enormous waste production of single-use PPE used in the healthcare system, especially during pandemics.