4 recent research articles examine N95 respirator mask sterilization methods

By Christopher Cheney

N95 respirator masks have been in limited supply since the beginning of the coronavirus disease 2019 (COVID-19) pandemic, and sterilization is a primary strategy to address shortages of this key personal protection equipment.

N95 respirator masks, which filter at least 95% of 0.3-μm particles, are the gold standard for protection against airborne pathogens such as the novel coronavirus. To conserve supplies of N95 respirator masks, the Centers for Disease Control and Prevention recommends that the masks be used by healthcare workers at highest risk of contracting infection or experiencing complications of infection.

Research on sterilizing N95 respirator masks for reuse includes four recent articles.

Viable alternatives to new N95 masks

Used N95 respirator masks treated with ethylene oxide or vaporized hydrogen peroxide maintain their filtration efficiency, according to a study published by JAMA Internal Medicine. Steam sterilization distorted 1860 N95 respirator masks, rendering them unsuitable for reuse; however, steam sterilization of 1870+ Aura face masks was effective, with the masks retaining more than 95% fitted filtration efficiency after a single sterilization cycle, the study found.

The JAMA Internal Medicine study also found that N95 respirator masks as many as 11 years past their expiration date maintained their filtration efficiency.

Four N95 decontamination methods effective

A recent research article, which was published in JAMA Otolaryngology—Head & Neck Surgery, identifies four decontamination methods that can recycle N95 masks without compromising the fit of the masks or the filtering material. The sterilization methods identified are ultraviolet germicidal irradiation, vaporized hydrogen peroxide, steam treatment, and dry heat treatment.

Steam sterilization for N95 masks

Two recent studies show steam can effectively decontaminate medical masks including N95 respirator masks.

A research team in China published a study in the Journal of Medical Virology on using steam to sanitize surgical masks and N95 respirators. The sanitization process, which used avian coronavirus of infectious bronchitis virus to mimic the novel coronavirus, was simple. Contaminated masks were placed in plastic bags and steamed over boiling tap water in a kitchen pot.

Researchers at Houston Methodist Research Institute in Houston published a steam sanitization study for N95 respirator masks in the journal Infection Control & Hospital Epidemiology. The study featured five test subjects to verify mask fit after the decontamination process and a more sophisticated steam treatment method than the Chinese study.

Christopher Cheney is the senior clinical care​ editor at HealthLeaders.