Assessing the impact of multiple ultraviolet disinfection cycles on N95 filtering facepiece respirator integrity

C Carolina Ontiveros,Christopher Smith,Sean Macisaac,Crystal L Sweeney,Sebastian Munoz,Graham A Gagnon,Jessica L Bennett,Amina K Stoddart

doi:10.1038/s41598-021-91706-1

C Carolina Ontiveros, Christopher Smith + Show 6 more

Open Access

https://doi.org/10.1038/s41598-021-91706-1

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Abstract

During the COVID-19 pandemic, N95 filtering facepiece respirators (FFRs) were recommended to protect healthcare workers when providing care to infected patients. Despite their single-use disposable nature, the need to disinfect and repurpose FFRs is paramount during this global emergency. The objectives of this study were to (1) determine if UV treatment has an observable impact on respirator integrity; (2) test the impact of UV treatment on N95 FFR user fit; and (3) test the impact of UV treatment on FFR integrity. Ultraviolet (UV) disinfection was assessed in maintaining N95 FFR integrity. Two models of FFRs were exposed to UV fluences ranging from 0 to 10,000 mJ cm−2 per side and subsequently tested for fit, respirator integrity, and airflow. Inspection of N95 FFRs before and after UV treatment via microscopy methods showed no observable or tactile abnormalities in the integrity of respirator material or straps. Tensile loading tests on UV-treated and untreated respirator straps also demonstrated no impact on breaking strength. Standardized fit test methods showed no compromise in user fit following UV treatment. Evaluation of particle penetration and airflow through N95 FFRs showed no impact on integrity, and average filtration efficiency did not fall below 95% for any of the respirator types or fluence levels. This work provides evidence that UV disinfection does not compromise N95 FFR integrity at UV fluences up to 10,000 mJ cm−2. UV disinfection is a viable treatment option to support healthcare professionals in their strategy against the spread of COVID-19.

Highlights

During the COVID-19 pandemic, N95 filtering facepiece respirators (FFRs) were recommended to protect healthcare workers when providing care to infected patients
Previous work has indicated that UV doses up to 950,000 mJ cm−2 (950 × higher than the present study) at 254 nm do not impact the efficacy, structure or integrity of N95 FFRs, indicating that UV treatment may be a promising disinfectant technology for repurposing N95 FFRs17
Another recent study analyzed the effect on respirator material morphology and hydrophobicity after exposure of up to 10,000 mJ cm−2 UV fluence using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), optical microscopy, and surface contact angle measurements and found no changes in these properties[17]

Summary

Introduction

During the COVID-19 pandemic, N95 filtering facepiece respirators (FFRs) were recommended to protect healthcare workers when providing care to infected patients. In order to mitigate disease transmission, the N95 filtering facepiece respirator (FFR) or higher-level respirator is recommended for performing aerosol-generating medical procedures (AGMP) in infected patients, such as open suctioning of airways, cardiopulmonary resuscitation, endotracheal intubation and extubation, and manual ventilation[3,4]. Amid this global emergency, the increasing demand for N95 FFRs is outpacing availability, and the development of timely methods for disinfecting and repurposing single-use FFRs is imperative. It is imperative to ensure that disinfection strategies are both effective and maintain the integrity of N95 FFRs to ensure fit and filtration efficiency are not negatively impacted

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