Effectiveness of Ultraviolet-C Light and a High-Level Disinfection Cabinet for Decontamination of N95 Respirators

Main Article Content

Jennifer L. Cadnum
Daniel Li
Sarah N. Redmond
Amrita R. John
Basya Pearlmutter
Curtis Donskey


Background-Shortages of personal protective equipment (PPE) including N95 filtering facepiece respirators is an urgent concern in the setting of the global COVID-19 pandemic.  Decontamination of PPE could be useful to maintain adequate supplies, but there is uncertainty regarding the efficacy of decontamination technologies.

Methods-A modification of the American Society for Testing and Materials standard quantitative carrier disk test method (ASTM E-2197-11) was used to examine the effectiveness of ultraviolet-C (UV-C) light, a high-level disinfection cabinet that generates aerosolized peracetic acid and hydrogen peroxide, and dry heat at 70°C for 30 minutes for decontamination of bacteriophages Phi6 and MS2 and methicillin-resistant Staphylococcus aureus (MRSA) inoculated onto 3 commercial N95 respirators.  Three and 6 log10 reductions on N95 respirators were considered effective for decontamination and disinfection, respectively. 

Results-UV-C administered as a 1-minute cycle in a UV-C box or a 30-minute cycle by a room decontamination device reduced contamination but did not meet criteria for decontamination of the viruses from all sites for any of the N95s.  The high-level disinfection cabinet was effective for decontamination of all the organisms from the N95s and achieved disinfection with 3 disinfection cycles over ~60 minutes.  Dry heat at 70°C for 30 minutes was not effective for decontamination of the bacteriophages.

  Conclusions-UV-C could be useful to reduce contamination on N95 respirators.  However, the UV-C technologies studied did not meet our criteria for decontamination under the test conditions used.  The high-level disinfection cabinet was effective for decontamination of N95s and met criteria for disinfection with multiple cycles.

Article Details



1. Tomas ME, Kundrapu S, Thota P, Sunkesula VC, Cadnum JL, Mana TS, Jencson A, O'Donnell M, Zabarsky TF, Hecker MT, Ray AJ, Wilson BM, Donskey CJ. Contamination of the skin and clothing of healthcare personnel during removal of personal protective equipment. JAMA Intern Med 2015;175:1904-10. doi: 10.1001/jamainternmed.2015.4535.

2. Ranney ML, Griffeth V, Jha AK. Critical Supply Shortages - The Need for Ventilators and Personal Protective Equipment during the Covid-19 Pandemic. N Engl J Med 2020 Mar 25. doi: 10.1056/NEJMp2006141.

3. https://www.cdc.gov/niosh/topics/hcwcontrols/recommendedguidanceextuse.html

4. Lore MB, Heimbuch BK, Brown TL, Wander JD, Hinrichs SH. Effectiveness of Three Decontamination Treatments against Influenza Virus Applied to Filtering Facepiece Respirators. Ann Occupat Hyg 2012;56:92–101. https://doi.org/10.1093/annhyg/mer054

5. Viscusi DJ, Bergman MS, Eimer BC, Shaffer RS. Evaluation of Five Decontamination Methods for Filtering Facepiece Respirators. Ann Occup Hyg 2009;53:815–827. https://doi.org/10.1093/annhyg/mep070

6. Heimbuch BK, Wallace WH, Kinney K, Lumley AE, Wu C, Woo M, Wander JD. A pandemic influenza preparedness study: use of energetic methods to decontaminate filtering facepiece respirators contaminated with H1N1 aerosols and droplets. Am J Infect Control 2011;39:e1-e9. doi: 10.1016/j.ajic.2010.07.004.

7. Fisher EM, Shaffer RE. A method to determine the available UV‐C dose for the decontamination of filtering facepiece respirators. J Appl Microbiol 2011;110: 287-295. doi: 10.1111/j.1365-2672.2010.04881.x.

8. Lowe JL, Paladino KD, Farke JD, Boulter K, Cawcutt K, Emodi M, Gibbs S, Hankins R, Hinkle L, Micheels T, Schwedhelm S, Vasa A, Wadman M, Watson S, and Rupp ME. N95 Filtering Facemask Respirator Ultraviolet Germicidal Irradiation (UVGI) Process for Decontamination and Reuse. 2020. https://www.nebraskamed.com/for-providers/covid19

9. Schwartz A, Stiegel M, Greeson N, Vogel A, Thomann W, Brown M, Sempowski GD, Alderman TS, Condreay JP, Burch J, Wolfe C, Smith B, and Lewis S. Decontamination and Reuse of N95 Respirators with Hydrogen Peroxide Vapor to Address Worldwide Personal Protective Equipment Shortages During the SARS-CoV-2 (COVID-19) Pandemic. Applied Biosafety: Journal of ABSA International. 2020. Preprint. https://absa.org/decontamination-and-reuse-of-n95-respirators-with-hydrogen-peroxide-vapor-to-address-worldwide-personal-protective-equipment-shortages-during-the-sars-cov-2-covid-19-pandemic/

10. Lindsley WG, Martin Jr. SB, Thewlis RE, Sarkisian K, Nwoko JO, Mead KR, Noti JD. Effects of Ultraviolet Germicidal Irradiation (UVGI) on N95 Respirator Filtration Performance and Structural Integrity. J Occup Envviron Hyg 2015;12:509-517. DOI: 10.1080/15459624.2015.1018518.

11. 3M Personal Safety Division. Disinfection of Filtering Facepiece Respirators Technical Bulletin. 2020. https://www.3m.com/3M/en_US/worker-health-safety-us/all-stories/full-story-detail/?storyid=8855304f-01cb-4af2-8937-83096cdb4113

12. Mana TS, Sitzlar B, Cadnum JL, Jencson AL, Koganti S, Donskey CJ. Evaluation of an automated room decontamination device using aerosolized peracetic acid. Am J Infect Control 2017;45:327-329. doi: 10.1016/j.ajic.2016.10.006.

13. Kumar JA, Cadnum JL, Jencson AL, Donskey CJ. Efficacy of a multi-purpose high level disinfection cabinet against Candida auris and other health care-associated pathogens. Am J Infection Control 2019 Dec 23. pii: S0196-6553(19)31016-8. doi: 10.1016/j.ajic.2019.11.029.

14. Boyce JM, Donskey CJ. Understanding ultraviolet light surface decontamination in hospital rooms: A primer. Infect Control Hosp Epidemiol 2019;40:1030–1035. doi:10.1017/ice.2019.161

15. Donskey CJ. Decontamination devices in health care facilities: Practical issues and emerging applications. Am J Infect Control 2019;47S:A23-A28. doi: 10.1016/j.ajic.2019.03.005.

16. Smolle C, Huss F, Lindblad M, Reischies F, Tano E. Effectiveness of automated ultraviolet-C light for decontamination of textiles inoculated with Enterococcus faecium. Am J Infect Control 2018;98:102-104. doi: 10.1016/j.jhin.2017.07.034.

17. Casanova LM. Evaluation of eluents for the recovery of an enveloped virus from hands by whole-hand sampling. J Appl Microbiol 2015;118:1210-1216. doi:10.1111/jam.12777.

18. ASTM International, Designation E2197: Standard Quantitative Disk Carrier Test Method for Determining Bactericidal, Virucidal, Fungicidal, Mycobactericidal, and Sporicidal Activities of Chemicals, 2011.

19. Masiuk T, Kadakia P, Wang Z. Development of a Physiologically Relevant Dripping Analytical Method Using Simulated Nasal Mucus for Nasal Spray Formulation Analysis. J Pharmaceut Anal 2016;6:283–291. doi:10.1016/j.jpha.2016.05.003.

20. Rutala WA, Kanamori H, Gergen MF, Sickbert-Bennett EE, Weber DJ. Susceptibility of Candida auris and Candida albicans to 21 germicides used in healthcare facilities. Infect Control Hosp Epidemiol 2019;40:380-382. doi: 10.1017/ice.2019.1.

21. Nerandzic MM, Thota P, Sankar C T, Jencson A, Cadnum JL, Ray AJ, Salata RA, Watkins RR, Donskey CJ. Evaluation of a pulsed xenon ultraviolet disinfection system for reduction of healthcare-associated pathogens in hospital rooms. Infect Control Hosp Epidemiol 2015;36:192-7. doi: 10.1017/ice.2014.36.

22. Cadnum JL, Jencson AL, Gestrich SA, Livingston SH, Karaman BA, Benner KJ, Wilson BM, Donskey CJ. A comparison of the efficacy of multiple ultraviolet light room decontamination devices in a radiology procedure room. Infect Control Hosp Epidemiol 2019;40:158-163. doi: 10.1017/ice.2018.296.

23. Final Report for the Bioquell Hydrogen Peroxide Vapor (HPV) Decontamination for Reuse of N95 Respirators. In: Threats FOoCaE, ed.: Battelle; 2016.

24. Darnell ME, Subbarao K, Feinstone SM, Taylor DR. Inactivation of the coronavirus that induces severe acute respiratory syndrome, SARS-CoV. J Virol Methods 2004;121:85-91.

25. Firquet S, Beaujard S, Lobert PE, et al. Viruses contained in droplets applied on warmed surface are rapidly inactivated. Microbes Environ. 2014;29(4):408–412. doi:10.1264/jsme2.ME14108.

26. Rabenau HF, Cinatl J, Morgenstern B, Bauer G, Preiser W, Doerr HW. Stability and inactivation of SARS coronavirus. Med Microbiol Immunol 2005;194:1–6. doi:10.1007/s00430-004-0219-0.

27. Leclercq I, Batéjat C, Burguière AM, Manuguerra JC. Heat inactivation of the Middle East respiratory syndrome coronavirus. Influenza Other Respir Viruses 2014;8:585–586. doi:10.1111/irv.12261.

28. Tseng CC, Li CS. Inactivation of viruses on surfaces by ultraviolet germicidal irradiation. J Occup Environ Hyg 2007;4:400-5.