Experimental and numerical analysis of the impact of decontamination treatments on the filtration performance of N95 respirators*

Filtering facepiece respirators such as N95 masks are an effective measure against the spread of infectious diseases. The masks capture a significant proportion of droplets that are generated by speaking or coughing. However, the surge in the use of disposable respirators is susceptible to demand-supply gaps and disposal threatens the environment with a new kind of plastic pollution. Effective decontamination methods are thus highly sought to make the use of N95 respirators sustainable. In this work, we have investigated the filtration performance of the key filtration layers of meltblown nonwovens after treatment with four different decontamination methods: soap, liquid hydrogen peroxide, ultraviolet radiation, and moist heat treatment. Using X-ray microCT, we have analyzed the structural heterogeneity of the filtration layers after one and five cycles of decontamination treatment. The microCT scans were used to perform numerical simulations of the filtration efficiency. We show how the different decontamination treatments affect the nonwoven structure, the distribution of particle penetration depths, and the filtration efficiency. The insights can help to improve decontamination processes and provide guidance for appropriate disinfection of N95 respirators.