I wonder whether the results change with the pressure cooker.
I had ilizarov apparatus[1] on my legs for over a year(once during age 7 and another during age 15) and my mom used to sterilise the instruments (Scissors, Forceps) used for dressing wounds at home(every alternate day) in pressure cooker(on advice of the doctor).
I presume, pressure cookers are still being used for the sterilisation of instruments[2] in several parts of the world as its still common than an electric cooker.
I am sure they perform sterilization effectively, but introduction of water/steam (which is under pressure in a "pressure" cooker) will almost certainly deform a mask like an N95 mask.
My reading of the OP was that no water was to be used, and a towel is placed at the bottom to shield the mask from touching the heating element altogether.
Do not do this. Pressure cookers exist to accelerate cooking, by raising the boiling point of water above 100C, because pressure resists boiling. All plastics in the mask will deteriorate rapidly.
I had ilizarov apparatus[1] on my legs for over a year(once during age 7 and another during age 15) and my mom used to sterilise the instruments (Scissors, Forceps) used for dressing wounds at home(every alternate day) in pressure cooker(on advice of the doctor).
I presume, pressure cookers are still being used for the sterilisation of instruments[2] in several parts of the world as its still common than an electric cooker.
[1]https://en.wikipedia.org/wiki/Ilizarov_apparatus
[2]https://cdn.ymaws.com/sites/adint.site-ym.com/resource/resmg...