There are two goals here: a) determine whether the mask is damaged by the sterilization technique and b) determine whether that technique actually sterilizes.

There are two goals here: a) determine whether the mask is damaged by the sterilization technique and b) determine whether that technique actually sterilizes. The E. Coli experiment is for the latter goal. FWIW, E. coli are a pretty standard way for checking sterilization efficacy. They're easy to culture, fairly hardy, and non-pathogenic. Doing a first pass with live SARS-Cov2 would be incredibly foolhardy (what if the sterilization doesn't work?!)