Effect of UV-C germicidal irradiation (UVGI) on the structural integrity of N95 and KN95 respirators

Abstract

This study focuses on reprocessing a group of filtering facepiece respirators (FFR) using ultraviolet germicidal irradiation (UVGI). The aim is to explore the possibility of disinfecting selected KN95 FFRs, in comparison with the N95 FFRs, and assess their viability for reusage. For this purpose, five models of unused N95 and KN95 FFR models obtained from the hospital were exposed to UV-C light using a customized UVGI chamber. The material integrity of treated FFRs was examined in terms of particle penetration and strap tension. The surface morphology of all models is inspected to determine the visible changes of each FFR upon exposure to 1–100 cycles (1 cycle is equivalent to 1 J/cm² UV dose). The penetration test results indicate that the physical properties of the KN95 and N95 FFRs remain within permissible limits despite being reprocessed by up to 100 cycles (100 J/cm²). Using a microscope, the physical observations also reveal that no visible damage can be seen even after 100 J/cm² exposure. Apart from the filter bodies, the tension of each strap was also found to not be significantly affected by UV radiation by at least 10 disinfection cycles (10 J/cm²). This confirms that KN95, as well as N95 FFRs, can be subjected to UV treatment as a means of disinfection.

Keywords:

• Filtering facepiece respirator
• morphology
• penetration
• tensile
• UV radiation

Acknowledgment

The authors would like to express their sincere gratitude to Prototype Development Centre, Malaysian Nuclear Agency for the assistance in fabricating the LembayUVng-I UVGI box. The authors would also like to extend thanks to the NIOSH Director for the consent to use the mask filtration test facility. High appreciation goes to the management of the Malaysian Nuclear Agency and Malaysian Ministry of Health for their reviews, comments, and suggestions. The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the Malaysian Ministry of Health and the Ministry of Science, Technology, and Innovation, Malaysia. The mention of company names or products does not constitute endorsement by any of the above ministries.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The data that support the findings of this study are available from the corresponding author, upon reasonable request.