Researchers got hard data on this question by testing four N95 masks before and after UV sterilization. They tested four models of N95 masks by exposing masks to five different doses of UV light (also called “UVGI”) from 120 to 950 J/cm². They tested 10 different sizes of particles and used the data for whichever size particle penetrated the mask the most. The data showed almost no harm to performance. For most masks and most dosages, the degradation in particle capture was less than 1%.
So UV light disinfects N95 masks with less than a 2% harm to filtration effectiveness, allowing them to be re-used quickly.
Click here to read more on the test and other details of how UV light will affect your masks: https://smartairfilters.com/en/blog/uv-light-disinfects-masks/