Finally found an answer for mask sterilization

How to reuse an 9-95 mask…do’s and don’ts.

I was wrong that sterilizing the surface with alcohol would do the trick. Treatment with alcohol degrades the efficiency of the mask.

But hot air at 158F will do the trick.

Steam 125C will do the trick.

Soap and water will degrade the efficiency of the mask.

Hot water (boiling) may well be effective.