In the study, six commercially available N95 masks were sprayed with E. coli mimic virus and tested with five sterilization methods: dry heat (oven), wet heat (steamer), autoclave, ultraviolet light and alcohol spraying to observe the feasibility of repeated use.

Research results show that: five sterilization methods under certain conditions can completely kill E. coli on the mask, including 70 degrees Celsius oven for 30 minutes of dry heat method, and 30 seconds of ultraviolet sterilization method, the filtering effect on the mask has the least impact, six test masks of the filtering effect, can be maintained at more than 95%.

The general public thought that can be effective sterilization of alcohol, because it contains moisture, will destroy the electrostatic effect of the mask, but let the four test mask filtration efficiency is less than 95 percent, other such as wet heat method and autoclave sterilization method, will also let one of the test mask filtration efficiency is less than 95 percent, and high temperature and high pressure will make the mask serious deformation.

 

It is therefore recommended that.

1The N95 mask can be sterilized by using the dry heat method which works for 30 minutes in an oven at 70 degrees Celsius or by using the ultraviolet sterilization method for 30 seconds.

2The use of alcohol to disinfect the mask, will destroy the filtering effect of the mask

Of course, as the study emphasizes: reuse of N95 masks is generally not recommended, and reuse with dry heat, UV sterilization and sterilization should only be considered in cases of epidemic emergencies and extreme deficiency of the protective substances.