N95 Respirator Information – Literature on Decontamination and Research on New Product Performance by make and model

Interest in decontamination and re-use of N95 and similarly rated particle filtering face respirator (FFR) masks designed for single use remains high due to sustained unmet demand during the COVID-19 pandemic.

For those interested in respiratory protection including N95 FFR, this page has been updated with two new publications, including summaries and direct links, and a spreadsheet of testing information of hundreds of new FFR manufactured in various countries, performed by NIOSH and ECRI, a health quality institute.  

Decontamination and Reuse of N95 Filtering Facepiece Respirators: Where Do We Stand?
Lydia Cassorla, MD, MBA.
Anesthesia & Analgesia. 132(1):2-14, January 2021.

A comprehensive review on this topic has been published in the January 2021 Anesthesia & Analgesia, freely available here. Tables include a summary of methods best-supported by science, links to multiple trustworthy websites likely to provide updates on this topic, and multiple proprietary methods that have received FDA emergency use authorizations. 

Abstract:
The coronavirus disease 2019 (COVID-19) pandemic created an extraordinary demand for N95 and similarly rated filtering facepiece respirators (FFR) that remains unmet due to limited stock, production constraints, and logistics. Interest in decontamination and reuse of FFR, a product class designed for single use in health care settings, has undergone a parallel surge due to shortages. A worthwhile decontamination method must provide effective inactivation of the targeted pathogen(s), and preserve particle filtration, mask fit, and safety for a subsequent user. This discussion reviews the background of the current shortage, classification, structure, and functional aspects of FFR, and potentially effective decontamination methods along with reference websites for those seeking updated information and guidance. The most promising techniques utilize heat, hydrogen peroxide, microwave-generated steam, or ultraviolet light. Many require special or repurposed equipment and a detailed operational roadmap specific to each setting. While limited, research is growing. There is significant variation between models with regard to the ability to withstand decontamination yet remain protective. The number of times an individual respirator can be reused is often limited by its ability to maintain a tight fit after multiple uses rather than by the decontamination method itself. There is no single solution for all settings; each individual or institution must choose according to their need, capability, and available resources. As the current pandemic is expected to continue for months to years, and the possibility of future airborne biologic threats persists, the need for plentiful, effective respiratory protection is stimulating research and innovation. (Anesth Analg 2021;132:2–14)

Evaluation of N95 respirators, modified snorkel masks and low-cost powered air-purifying respirators: a prospective observational cohort study in healthcare workers. Clinkard D. 1/20/21. Anaesthesia.

Authors used qualitative fit testing in 51 individuals to evaluate N95 FFR, and snorkel masks adapted with either high efficiency filters (>99%) or positive air purifying respirators.  N95s failed one or more testing steps in 59%, and snorkel masks with high‐efficiency filters failed in 20% of participants. 24% and 12% failed overall fit factors, respectively. The snorkel masks adapted with low-cost powered‐air purifying respirators had zero individual or overall failures.

Repeated vaporised hydrogen peroxide disinfection of 3M 1860 N95 mask respirators does not degrade quantitative fit performance. Moschella P. 1/24/21. Br J Anaesth.

Authors tested randomly selected 3M model 1860 N95 respirators, a widely available model, for fit and function following repeated vaporised hydrogen peroxide (VHP) sterilization.  They found that fit and function were preserved after either 5 or 10 disinfection Bioquell VHP cycles. They used “gold standard” quantitative NIOSH fit testing including talking and head movements in accordance with 29 Code of Federal Regulations 1910.134, utilizing a TSI PortaCount® device.

Buyers of New N95 Respirators Beware
Individuals may be purchasing filtering facepiece respirators through retail and on-line purchasing options. Testing of hundreds of new filtering facepiece respirator models (N95-type FFR) from various countries was performed by ECRI, a healthcare quality institute, and NIOSH, the National Institute of Occupational Safety and Health and made available at the end of October, 2020. Many did not meet the advertised performance. See the 2-tab spreadsheet here.

Disclaimer
The material on this website is provided for informational purposes and does not constitute medical advice. New knowledge is added daily and may change over time. Opinions expressed should not be construed as representing IARS policy or recommendations. References and links to third parties do not constitute an endorsement or warranty by IARS.

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Lydia Cassorla, MD, MBA
Specialty: Anesthesiology
Professor Emerita, Department of Anesthesia and Perioperative Care, University of California, San Francisco
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St. Joseph Hospital
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