To combat Covid-19 amid supply shortages in 2020, healthcare facilities across the United States resorted to disinfecting personal protective equipment (PPE), such as N95 masks, for reuse with methods such as ultraviolet (UV) light. But questions lingered about the safety and efficacy of these methods and how best to implement them.

Now, in perhaps the most rigorous examination of UV light’s effects on N95 masks yet, researchers at the National Institute of Standards and Technology (NIST) have shown that these masks can be disinfected with little effect on their form or function. In a study published in the Journal of Research of the National Institute of Standards and Technology, the researchers, with help from federal and private partners, scrutinized UV-exposed N95 masks for traces of virus and looked for changes in the shape of their fibers, ability to filter out aerosols, and other properties.

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