N95 Respirators Prove Effectively Disinfected With Ultraviolet Radiation

With a pandemic and thoughts of others in the future highlighted on the world stage, personal protective equipment (PPE) is key to keeping individuals safe. Also, increasing demand and lack of PPEs in the supply chain caused significant disruptions during the early days of the COVID-19 pandemic. To stave off possible issues in the future, investigators the National Institute of Standards and Technology (NIST) examined UV light’s effects on N95 masks, have demonstrated that these masks can be disinfected with little impact on their form or function. In a new study, Disinfection of Respirators with Ultraviolet Radiation,” published in the Journal of Research of the National Institute of Standards and Technology, the investigators, 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.

The investigation “brought together folks from the federal and the private sector organizations who have interests in looking at the capabilities of ultraviolet radiation for the disinfection and reuse of personal protective equipment,” Dianne L. Poster, PhD, and lead investigator of the study, told Infection Control Today® recently about the study in an exclusive interview. “In this case, we specifically investigated ultraviolet radiation for the disinfection and reuse of N95 face filtering respirators [FFRs]. These are an important component in the suite of PPE, and they are a type of mask that offers protection for users from the potential risk of inhaling airborne particles. And [with] researchers at the National Institute of Standards and Technology in collaboration with our federal and private sector organizations, we demonstrated that these masks can be disinfected with very little impact to their form and function.”

Despite the COVID-19 pandemic winding down, the N95 FFRs continue to be in demand, domestically and internationally, and the interest in using UV-C radiation for disinfection and reuse of N95 FFRs remains high. The Delta and Omicron variants of SARS-CoV-2 has has greatly increased the demand for N95 FFRs, especially given the increased risks of infectivity associated with their aerosol transmission. In addition, everyday care around the world involving other transmissible diseases, such as measles, continues to draw on the global supply of N95 FFRs. Just as importantly, reuse is also of interest to reduce waste and environmental pollution.

The study, however, “is not intended to quantify the safety of any N95 FFR. It is highly recommended that testing should be undertaken on any products or systems being considered for N95 masks or any PPE disinfection and reuse,” the investigators said in the study. “Previous studies on UV disinfection of N95 FFRs for reuse strategies clearly indicated the importance of measuring the integrity of respirator fit and seal following any disinfection treatment. It is also important to seek guidance from impartial authorities to confirm that any implied standards are met through testing and evaluation. This is especially true for face coverings because these highly differ from one another and require different types of tests and evaluations for their reuse.”

Poster tells ICT® that the study is vital and, in the future, other factors of reusing N95 FFRs must be considered. “The fundamental results from these studies can be used to build on topics that are related to the use of ultraviolet technologies for disinfection, and, in particular, for the case of personal protective equipment and N95 FFRs. But I think based on our analysis of these data, it would be useful to look at different types of conditions of the N95 masks after they've been used in different capacities,” Poster said. “Effects of soiling, perhaps different levels of soiling, on the masks were not examined in this study. Soiling could come from sources such as saliva, skin oils, or cosmetics; those types of parameters should be investigated. Also, the effects of fluid absorption due to breathing breath as your breath passes across the interface of the mask and or phlegm on the interior surface could be a factor. Those types of things would be very beneficial to look at in the future.”