Comment on: “Proposed approach for reusing surgical masks in COVID-19 pandemic”
Authors: Angeli Eloise Torres, David M. Ozog, Iltefat H. Hamzavi, Henry W. Lim
Journal: Journal of the American Academy of Dermatology (2020)

To the Editor: The article by Liu et al1Liu Y. Leachman S. Bar A. Proposed approach for reusing surgical masks in COVID-19 pandemic.J Am Acad Dermatol. 2020; 83: e53-e54Abstract Full Text Full Text PDF PubMed Scopus (15) Google Scholar provided valuable recommendations regarding the use of dry heat to facilitate surgical mask reuse. Prior studies exploring this method have largely focused on its effect on N95 respirator integrity rather than a quantification of its virucidal activity.2Torres A.E. Lyons A.B. Narla S. et al.Ultraviolet-C and other methods of decontamination of filtering facepiece N-95 respirators during the COVID-19 pandemic.Photochem Photobiol Sci. 2020; 19: 746-751Crossref Google Scholar This makes it difficult to compare its virucidal advantage over ultraviolet C (UVC) and other methods.2Torres A.E. Lyons A.B. Narla S. et al.Ultraviolet-C and other methods of decontamination of filtering facepiece N-95 respirators during the COVID-19 pandemic.Photochem Photobiol Sci. 2020; 19: 746-751Crossref Google Scholar Dry heating requires direct supervision during its delivery, because too high a temperature (>100°C) is known to decrease the filtering capacity of respirators and masks.2Torres A.E. Lyons A.B. Narla S. et al.Ultraviolet-C and other methods of decontamination of filtering facepiece N-95 respirators during the COVID-19 pandemic.Photochem Photobiol Sci. 2020; 19: 746-751Crossref Google Scholar In addition, the effect of dry heating on respirator—and possibly mask—integrity varies significantly depending on the approach used (laboratory oven, dry microwaving, or rice cooker without water)2Torres A.E. Lyons A.B. Narla S. et al.Ultraviolet-C and other methods of decontamination of filtering facepiece N-95 respirators during the COVID-19 pandemic.Photochem Photobiol Sci. 2020; 19: 746-751Crossref Google Scholar and the specific respirator or mask model. For N95 respirators, failure of fit-testing after decontamination would have potential catastrophic effects on health care providers.3Ozog D. Parks-Miller A. Kohli I. et al.The importance of form fit testing in decontamination of N95 respirators: a cautionary note.J Am Acad Dermatol. 2020; 83: 672-674Abstract Full Text Full Text PDF PubMed Scopus (18) Google Scholar The authors' statement pertaining to UVC having "less penetration" and being "less virucidal" contradicts previous reports.2Torres A.E. Lyons A.B. Narla S. et al.Ultraviolet-C and other methods of decontamination of filtering facepiece N-95 respirators during the COVID-19 pandemic.Photochem Photobiol Sci. 2020; 19: 746-751Crossref Google Scholar,4Hamzavi I.H. Lyons A.B. Kohli I. et al.Ultraviolet germicidal irradiation: possible method for respirator disinfection to facilitate reuse during COVID-19 pandemic.J Am Acad Dermatol. 2020; 82: 1511-1512Abstract Full Text Full Text PDF PubMed Scopus (102) Google Scholar Although UVC is known foremost as a surface decontaminant, our observations using a desktop UVC unit (Daavlin Desktop UVC Germicidal Lamp, Daavlin, Bryan, OH) indicated that when the outside-facing surface of N95 respirators is irradiated at virucidal dose (1 J/cm2),4Hamzavi I.H. Lyons A.B. Kohli I. et al.Ultraviolet germicidal irradiation: possible method for respirator disinfection to facilitate reuse during COVID-19 pandemic.J Am Acad Dermatol. 2020; 82: 1511-1512Abstract Full Text Full Text PDF PubMed Scopus (102) Google Scholar 10% of the dose can penetrate to the wearer-facing surface (Kohli et al, unpublished data, 2020). Hence, it is very likely that surgical masks may yield even greater UVC penetration given their larger particle penetration compared with respirators.1Liu Y. Leachman S. Bar A. Proposed approach for reusing surgical masks in COVID-19 pandemic.J Am Acad Dermatol. 2020; 83: e53-e54Abstract Full Text Full Text PDF PubMed Scopus (15) Google Scholar Furthermore, the addition of a reflective base, flipping of the masks, or the availability of units that allow irradiation of both surfaces of the mask at the same time (Orbitform Mask Sanitizer, Orbitform Medical, Jackson, MI)2Torres A.E. Lyons A.B. Narla S. et al.Ultraviolet-C and other methods of decontamination of filtering facepiece N-95 respirators during the COVID-19 pandemic.Photochem Photobiol Sci. 2020; 19: 746-751Crossref Google Scholar can facilitate adequate irradiation of all surfaces. Although testing against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has not been done, UVC has documented activity (≥3-log reduction) against SARS-CoV, Middle East respiratory syndrome coronavirus (MERS-CoV),5Bedell K. Buchaklian A.H. Perlman S. Efficacy of an automated multiple emitter whole-room ultraviolet-C disinfection system against coronaviruses MHV and MERS-CoV.Infect Control Hosp Epidemiol. 2016; 37: 598-599Crossref PubMed Scopus (103) Google Scholar and H1N1 influenza A virus.6Mills D. Harnish D.A. Lawrence C. Sandoval-Powers M. Heimbuch B.K. Ultraviolet germicidal irradiation of influenza-contaminated N95 filtering facepiece respirators.Am J Infect Control. 2018; 46: e49-e55Abstract Full Text Full Text PDF PubMed Scopus (188) Google Scholar This was achieved after irradiation of N95 respirators at a dose of 1 J/cm2 per side delivered in under 3 minutes.4Hamzavi I.H. Lyons A.B. Kohli I. et al.Ultraviolet germicidal irradiation: possible method for respirator disinfection to facilitate reuse during COVID-19 pandemic.J Am Acad Dermatol. 2020; 82: 1511-1512Abstract Full Text Full Text PDF PubMed Scopus (102) Google Scholar For surgical masks, being of a thinner material, it is likely that the required dose and irradiation time is even lower. Proposed approach for reusing surgical masks in COVID-19 pandemicJournal of the American Academy of DermatologyVol. 83Issue 1PreviewTo the Editor: Coronavirus disease 2019 (COVID-19) is a novel human respiratory disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus. Washing hands and social distancing are measures recommended by the Centers for Disease Control and Prevention to prevent COVID-19 transmission. However, new evidence shows that the half-life of viable SARS-CoV-2 in aerosol is longer than 1 hour, indicating a high likelihood of airborne transmission.1 Furthermore, the existence of an asymptomatic carrier phase decreases the effectiveness of prevention strategies that rely on symptoms. Full-Text PDF Reply to: Comments on "Proposed approach for reusing surgical masks in COVID-19 pandemic"Journal of the American Academy of DermatologyVol. 83Issue 3PreviewTo the Editor: We appreciate the thoughtful comments by Dr Torres et al,1 which provide convincing evidence that ultraviolet (UV) C is capable of penetrating through face mask material to inactivate virus.2 We agree that UV irradiation is an acceptable approach for surgical mask decontamination. Reuse of masks is not ideal and should be reserved for situations in which there is no alternative. Further, the best method of decontamination, if the need arises, will vary at different institutions where a variety of equipment may (or may not) exist. Full-Text PDF