Light propagation within <scp>N95</scp> filtered face respirators: A simulation study for <scp>UVC</scp> decontamination

Lilge, Lothar; Manalac, Angelica; Weersink, Madrigal; Schwiegelshohn, Fynn; Young‐Schultz, Tanner; Abdalrhman, Abdallatif Satti; Wang, Chengjin; Ngan, Aldrich; Gu, Frank; Betz, Vaughn; Hofmann, Ron

doi:10.1002/jbio.202000232

Cited by 11 publications

(9 citation statements)

References 21 publications

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“…We could not discriminate the relative contributions from absorbance and scattering to this attenuation coefficient because we did not have a setup to measure reflectivity. Lilge et al studied the light distribution within N95 masks and provide data for the relative strength of absorbance and scattering coefficients of the materials in the 3M 8210 mask from integrating sphere reflectance and transmittance measurements (70). Here, we extend our model using the Kubelka theory (83,84) to include the contributions of diffuse reflectance on the light distribution within the multilayer structure of the N95 mask.…”

Section: Appendix: Modeling the Light Distribution In A Multilayer Structure Accounting For Diffuse Reflectancementioning

confidence: 99%

“…Preprints are snapshots in time of science that sometimes is in rapid flux. Since then, related results were published in several preprints and published works discussed below (36,(65)(66)(67)(68)(69)(70)(71)(72)(73)(74)(75)(76)(77)(78)(79)(80).…”

Section: Present and Future Importance Of N95 Emergency Reusementioning

confidence: 99%

“…Sears et al modeled the effects of uneven UV-C exposure of masks from two sides due to mask curvature, and they suggest the use of multidirectional UV-C irradiation to improve decontamination (76). Lilge et al determined the optical scattering and absorbance coefficients of several N95 mask materials using diffuse transmission and reflection measurements with an integrating sphere and an array spectrophotometer, and they used these parameters for Monte Carlo modeling the light distribution within the layers of the mask (70). Their modeling of the single-sided light distribution within the 3M 8210 mask suggests about 4-log-order reduction from the surface light fluence.…”

Section: Present and Future Importance Of N95 Emergency Reusementioning

confidence: 99%

“…We use Eqs. 21 and 22 to calculate the transmittance and reflectance of the combined filter 1 and filter 2 (see Table 1) for comparison with the data for the filter layer from Lilge et al (70).…”

Section: Appendix: Modeling the Light Distribution In A Multilayer Structure Accounting For Diffuse Reflectancementioning

confidence: 99%

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Principles and practice for SARS-CoV-2 decontamination of N95 masks with UV-C

Huber

Goldman

Epstein

et al. 2021

Biophysical Journal

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A mainstay of personal protective equipment during the coronavirus disease 2019 pandemic is the N95 filtering facepiece respirator. N95 respirators are commonly used to protect healthcare workers from respiratory pathogens, including the novel coronavirus severe acute respiratory syndrome coronavirus 2, and are increasingly employed by other frontline workers and the general public. Under routine circumstances, these masks are disposable, single-use items, but extended use and reuse practices have been broadly enacted to alleviate critical supply shortages during the coronavirus disease 2019 pandemic. Although extended-time single use presents a low risk of pathogen transfer, repeated donning and doffing of potentially contaminated masks presents increased risk of pathogen transfer. Therefore, efficient and safe decontamination methods for N95 masks are needed to reduce the risk of reuse and mitigate local supply shortages. Here, we review the available literature concerning use of germicidal ultraviolet-C (UV-C) light to decontaminate N95 masks. We propose a practical method for repeated point-of-use decontamination using commercially available UV-C cross-linker boxes from molecular biology laboratories to expose each side of the mask to 800-1200 mJ/cm 2 of UV-C. We measure the dose that penetrated to the interior of the respirators and model the potential germicidal action on coronaviruses. Our experimental results, in combination with modeled data, suggest that such a UV-C treatment cycle should induce a >3-log-order reduction in viral bioburden on the surface of the respirators and a 2-log-order reduction throughout the interior. We find that a dose 50-fold greater does not impair filtration or fit of 3M 8210 N95 masks, indicating that decontamination can be performed repeatedly. As such, UV-C germicidal irradiation is a practical strategy for small-scale point-of-use decontamination of N95s.

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Section: Appendix: Modeling the Light Distribution In A Multilayer Structure Accounting For Diffuse Reflectancementioning

confidence: 99%

Section: Present and Future Importance Of N95 Emergency Reusementioning

confidence: 99%

Section: Present and Future Importance Of N95 Emergency Reusementioning

confidence: 99%

Section: Appendix: Modeling the Light Distribution In A Multilayer Structure Accounting For Diffuse Reflectancementioning

confidence: 99%

See 2 more Smart Citations

Principles and practice for SARS-CoV-2 decontamination of N95 masks with UV-C

Huber

Goldman

Epstein

et al. 2021

Biophysical Journal

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“…However, UVC radiation at 254 nm penetrates poorly through turbid and porous materials, such as N95 masks. Nevertheless, UVGI dosimetry can be adapted accordingly to promote effective microbicidal activity in porous materials [ 45 , 46 ].…”

Section: Introductionmentioning

confidence: 99%

Ultraviolet germicidal irradiation is effective against SARS-CoV-2 in contaminated makeup powder and lipstick

Bispo-dos-Santos

Barbosa

Granja

et al. 2021

Journal of Photochemistry and Photobiology

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Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is mainly transmitted by airborne droplets generated by infected individuals. Since this and many other pathogens are able to remain viable on inert surfaces for extended periods of time, contaminated surfaces play an important role in SARS-CoV-2 fomite transmission. Cosmetic products are destined to be applied on infection-sensitive sites, such as the lips and eyelids. Therefore, special biosafety precautions should be incorporated into the routine procedures of beauty parlors and shops. Indeed, innovative cosmetics companies are currently searching for disinfection protocols that ensure the customers’ safety in makeup testing. Here, we propose an ultraviolet germicidal irradiation (UVGI) strategy that can be used to reduce the odds of COVID-19 fomite transmission by makeup testers. It is well-known that UVGI effectively inactivates pathogens on flat surfaces and clear fluids. However, ultraviolet-C (UVC) radiation at 254 nm penetrates poorly in turbid and porous materials, such as makeup and lipstick formulations. Thus, we investigated the virucidal effect of UVGI against SARS-CoV-2 deposited on such substrates and compared their performance to that of flat polystyrene surfaces, used as controls. Concentrated infectious SARS-CoV-2 inoculum (10 6 PFU/mL) deposited on lipstick and makeup powder was completely inactivated (>5log 10 reduction) following UVC exposures at 1,260 mJ/cm 2 , while flat plastic surfaces required 10 times less exposure (126 mJ/cm 2 ) to reach the same microbicidal performance. We conclude that UVGI comprises an effective disinfection strategy to promote biosafety for cosmetics testers. However, appropriate UVC dosimetry must be implemented to overcome inefficiencies caused by the optical properties of turbid materials in lipsticks and makeup powders.

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UV Disinfection of Air and Surfaces

2022

Photochemical Reactors

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Light propagation within N95 filtered face respirators: A simulation study for UVC decontamination

Cited by 11 publications

References 21 publications

Principles and practice for SARS-CoV-2 decontamination of N95 masks with UV-C

Principles and practice for SARS-CoV-2 decontamination of N95 masks with UV-C

Ultraviolet germicidal irradiation is effective against SARS-CoV-2 in contaminated makeup powder and lipstick

UV Disinfection of Air and Surfaces

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