AIHce 2021: Q&A with Kathy Chan

Posted on Behalf of  Kathy Chan

What was the title of your presentation?

“A Critical Review of Methods for Decontaminating Filtering Facepiece Respirators”

What was the scope of your research?

This poster was based on a manuscript that was led by Neva Jacobs, with contributions and guidance from Dana Hollins. The manuscript is available here.

At the height of the COVID-19 pandemic, crisis strategies including the decontamination and subsequent reuse of filtering facepiece respirators (FFRs) were considered for implementation in overwhelmed healthcare settings. In this study, we performed a critical review of the available literature regarding decontamination methods to determine which strategies are effective at inactivating the target organism, preserve performance (filter efficiency and fit) of the respirator, leave no residual toxicity from the treatment, and are fast-acting, inexpensive, and readily available.

What did you find?

While FFR decontamination methods have been studied since 2007, reuse after decontamination of FFRs has historically not been recommended due to concerns that the filtration performance or fit of the respirator would be compromised. Decontamination of FFRs first became acceptable practice in April 2020 as a crisis strategy to conserve available supplies. In our critical review, we found that ultraviolet germicidal irradiation (UVGI) is the most widely studied method, and treatments are effective at inactivating SARS-CoV-2 without diminishing filtration efficiency or fit. These treatments were found to leave no residual toxicity for the wearer, have a relatively short cycle time of less than 1 h, and existing systems can likely be retrofitted to accommodate this method. Further, UVGI (among other treatment methods) has been recommended by the Centers for Disease Control and Prevention (CDC), Occupational Safety and Health Administration (OSHA), and respirator manufacturers. Methods involving microwave-generated steam also show potential in that they are likely effective against SARS-CoV-2, preserve performance, have no residual toxicity, require a short duration treatment cycle (often less than 10 min), and microwave ovens are inexpensive and readily available. Steam/moist heat methods are currently recommended by the CDC, OSHA, and manufacturers. These respirator decontamination methods are likely also useful against other viruses or pathogens.

What are the next steps/what other research is needed?

At the current stage of the COVID-19 pandemic, we have begun to transition away from crisis strategies including the decontamination and subsequent reuse of FFRs. However, understanding of these strategies can be useful should crisis scenarios in health care settings arise in the future. We examined multiple decontamination methods in our review, including UVGI, steam and moist heat, vaporous hydrogen peroxide, ethylene oxide gas, autoclave or dry heat, bleach, isopropyl alcohol, liquid hydrogen peroxide, soap and water, ethanol, and dry microwave methods. For all methods, additional research is needed to better understand their specific application and validation should be performed prior to implementation to ensure that the method is effective in any particular setting or with any particular FFR model type.