A University of Manitoba, Canada study advocates Autoclaving of N95 Masks as an accessible method for sterlisation of N95 masks for up to 10 cycles. https://news.umanitoba.ca/n95-mask-decontamination-using-standard-hospital-sterilization-technologies/

A Standford Medicine Anesthesia Informatics and Media Lab advisory entitled COVID-19 Evidence Service has tested and recommends the two following methods for sterlisation of N95 masks:

Method 1: 75 °C Hot air (30 min) for 20 cycles
Method 2: UV (254 nm, 8 W, 30 min) for 10 cycles.

https://stanfordmedicine.app.box.com/v/covid19-PPE-1-2

The advisory refers to the following study too:

Stability of SARS coronavirus in human specimens and environment and its sensitivity to heating and UV irradiation. - PubMed - NCBI
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