Effects of Ultraviolet Germicidal Irradiation (UVGI) on N95 Respirator Filtration Performance and Structural Integrity

Lindsley, William G.; Martin, Stephen B.; Thewlis, Robert E.; Sarkisian, Khachatur; Nwoko, Julian O.; Mead, Kenneth R.; Noti, John D.

doi:10.1080/15459624.2015.1018518

Cited by 233 publications

(388 citation statements)

References 13 publications

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“…Their lowest applied dose of 120,000 mJ/cm 2 reduced the bursting strength of the four N95 models tested by 11% to 42% (depending on the model and the individual layer), with very minor effects on filter aerosol penetration and filter airflow resistance (Table 3). An applied dose of 590,000 mJ/cm 2 reduced the breaking strength of straps from the four N95 FFR models tested by 10% to 21% 36 . It should be noted that their lowest dose is 120,000 mJ/cm 2 , which is 60 times higher than the conservative minimum dose of 2,000 mJ/cm 2 we recommend for SARS-CoV-2 inactivation.…”

Section: Uvgimentioning

confidence: 97%

“…Strap strength was unaffected by 10 UVGI cycles (total applied dose 10,000 mJ/cm 2 ), but 20 cycles had some effect on certain models. • Lindsley et al 36 went further, estimating the cumulative effect of extremely high exposures of N95 FFRs to UVC in order to mimic repeated cycles of UVGI treatment. Their lowest applied dose of 120,000 mJ/cm 2 reduced the bursting strength of the four N95 models tested by 11% to 42% (depending on the model and the individual layer), with very minor effects on filter aerosol penetration and filter airflow resistance (Table 3).…”

Section: Uvgimentioning

confidence: 99%

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Rapid evidence summary on SARS-CoV-2 survivorship and disinfection, and a reusable PPE protocol using a double-hit process

Derraik

Anderson

Connelly

et al. 2020

Preprint

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In the COVID-19 pandemic caused by SARS-CoV-2, hospitals are stretched beyond capacity. There are widespread reports of dwindling supplies of personal protective equipment (PPE), which are paramount to protect frontline medical/nursing staff and to minimize further spread of the virus. We carried out a rapid review to summarize the existing evidence on SARS-CoV-2 survivorship and methods to disinfect PPE gear, particularly N95 filtering facepiece respirators (FFR). In the absence of data on SARS-CoV-2, we focused on the sister virus SARS-CoV-1. We propose a two-step disinfection process, which is conservative in the absence of robust evidence on SARS-CoV-2. This disinfection protocol is based on an initial storage of PPE for ≥4 days, followed by ultraviolet light (UVC), dry heat treatment, or chemical disinfection. Importantly, each of the two steps is based on independent disinfection mechanisms, so that our proposed protocol is a multiplicative system, maximising the efficacy of our disinfection process. This method could be rapidly implemented in other healthcare settings, while testing of each method is undertaken, increasing the frontline supply of PPE, and avoiding many of the upstream issues of supply chain disruption currently being faced.

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Section: Uvgimentioning

confidence: 97%

Section: Uvgimentioning

confidence: 99%

Rapid evidence summary on SARS-CoV-2 survivorship and disinfection, and a reusable PPE protocol using a double-hit process

Derraik

Anderson

Connelly

et al. 2020

Preprint

View full text Add to dashboard Cite

show abstract

“…Another disadvantage is that UVGI was reported to significantly impact the mechanical strength of some FFRs with doses of around 1000 J/cm 2 . 34 Therefore, UVGI may be a useful disinfection technique, but the exact exposure or intensity of the UV-C light fluence on the mask surface would need to be verified. The variation in UVGI intensity has been the cause of discrepancies in the literature, as 3M's own internal reports recently showed that their UVGI treatments damaged particular FFRs, 35 whereas other reports show that UVGI cycling on multiple N95 FFRs had minimal or no impact.…”

mentioning

confidence: 99%

Can N95 respirators be reused after disinfection? And for how many times?

Liao

Wang

Zhao

et al. 2020

Preprint

109

192

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The Coronavirus Disease 2019 pandemic has led to a major shortage of N95 respirators, which are essential to protecting healthcare professionals and the general public who may come into contact with the virus. Thus, it is essential to determine how we can reuse respirators and other personal protection in these urgent times. We investigated multiple commonly used and easily deployable, scalable disinfection schemes on media with particle filtration efficiency of 95%. Among these, heating (≤85 °C) under various humidities (≤100% RH) was the most promising, nondestructive method for the preservation of filtration properties in meltblown fabrics as well as N95-grade respirators. Heating can be applied up to 50 cycles (85 °C, 30% RH) without observation in the degradation of meltblown filtration performance. Ultraviolet (UV) irradiation was a secondary choice which was able to withstand 10 cycles of treatment and showed small degradation by 20 cycles. However, UV can also potentially impact the material strength and fit of respirators. Finally, treatments involving liquids and vapors require caution, as steam, alcohol, and household bleach may all lead to degradation of the filtration efficiency, leaving the user vulnerable to the viral aerosols.

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“…The only study to observe either type of damage used a range of very high doses of UVGI. 4 At their lowest dose (120 Jcm −2 ), the only significant damage was that, for one model of mask, one layer of the filter became significantly more susceptible to being punctured by a steel ball (decreased burst strength). At higher doses damage gradually became more significant.…”

Section: Introductionmentioning

confidence: 99%

“…Fortunately, multiple studies have addressed this question. 4,5,12,13 Their results are summarized in table 1.…”

Section: Introductionmentioning

confidence: 99%

UV Sterilization of Personal Protective Equipment with Idle Laboratory Biosafety Cabinets During the COVID-19 Pandemic

Weaver

McElvany

Gopalakrishnan

et al. 2020

Preprint

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DISCLAIMER: This article does not represent the official recommendation of the Cleveland Clinic or CaseWestern Reserve University School of Medicine, nor has it yet been peer reviewed. We are releasing it early, pre-peer review, to allow for quick dissemination/vetting by the scientific/clinical community given the necessity for rapid conservation of personal protective equipment (PPE) during this dire global situation. We welcome feedback from the community.Personal protective equipment (PPE), including face shields, surgical masks, and N95 respirators, is crucially important to the safety of both patients and medical personnel, particularly in the event of an infectious pandemic. As the incidence of Coronavirus Disease (COVID-19) increases exponentially in the United States and worldwide, healthcare provider demand for these necessities is currently outpacing supply. As such, strategies to extend the lifespan of the supply of medical equipment as safely as possible are critically important. In the midst of the current pandemic, there has been a concerted effort to identify viable ways to conserve PPE, including decontamination after use. Some hospitals have already begun using UV-C light to decontaminate N95 respirators and other PPE, but many lack the space or equipment to implement existing protocols. In this study, we outline a procedure by which PPE may be decontaminated using ultraviolet (UV) radiation in biosafety cabinets (BSCs), a common element of many academic, public health, and hospital laboratories, and discuss the dose ranges needed for effective decontamination of critical PPE. We further discuss obstacles to this approach including the possibility that the UV radiation levels vary within BSCs. Effective decontamination of N95 respirator masks or surgical masks requires UV-C doses of greater than 1 Jcm −2 , which would take a minimum of 4.3 hours per side when placing the N95 at the bottom of the BSCs tested in this study. Elevating the N95 mask by 48 cm (so that it lies 19 cm from the top of the BSC) would enable the delivery of germicidal doses of UV-C in 62 minutes per side. Effective decontamination of face shields likely requires a much lower UV-C dose, and may be achieved by placing the face shields at the bottom of the BSC for 20 minutes per side. Our results are intended to provide support to healthcare organizations looking for alternative methods to extend their reserves of PPE. We recognize that institutions will require robust quality control processes to guarantee the efficacy of any implemented decontamination protocol. We also recognize that in certain situations such institutional resources may not be available; while we subscribe to the general principle that some degree of decontamination is preferable to re-use without decontamination, we would strongly advise that in such cases at least some degree of on-site verification of UV dose delivery be performed.

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Effects of Ultraviolet Germicidal Irradiation (UVGI) on N95 Respirator Filtration Performance and Structural Integrity

Cited by 233 publications

References 13 publications

Rapid evidence summary on SARS-CoV-2 survivorship and disinfection, and a reusable PPE protocol using a double-hit process

Rapid evidence summary on SARS-CoV-2 survivorship and disinfection, and a reusable PPE protocol using a double-hit process

Can N95 respirators be reused after disinfection? And for how many times?

UV Sterilization of Personal Protective Equipment with Idle Laboratory Biosafety Cabinets During the COVID-19 Pandemic

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