Advice collected from doctors posting on various Chinese social websites by Xiaotang Jiang
Two principles to reusing your masks:
1. high temperature
2. no-water contact
For Covid-19 30 minutes at temperature above 56 degrees (133 F) is needed to deactivate the virus.
Do not wash the mask! The secret of strong protection ability of N95 is electrostatic adsorption. (See here https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6164087/ )
If you open a N95 mask, you would see a layer of meltblown non-woven fabric, which made of polypropylene and is a kind of ultra-fine electrostatic fiber. When you breathe through the non-woven fabric, the air passes normally, and all the dust and toxic droplets are all electrostatically captured. If you think about how your hair gets stuck to a a sweater in winter, the principle of N95 protection is similar.
After the air dust is electrostatically adsorbed, it is extremely difficult to detach, and there is no way to clean it. As long as the static electricity is present, the dust and germs are always there.
Static electricity fears water. If the static electricity is gone, the mask will be useless and become a normal cotton mask.
Three major measures people practice in China to reuse masks:
- UV Sterilization
- dry heater (e.g hot portable heater at home)
- old style (seal the masks in a jar and put the bottle in boiling water for 10 mins)
Some people recommend spraying with 75% medical alcohol and leaving it to dry. 75% alcohol is ideal – 95% need to be diluted (when the concentration high, the dehydration reaction will be too fast, causing the contacted proteins to quickly coagulate, forming a protective hard film on the surface of the virus to prevent the penetration of alcohol)
N95 mask is designed for medical professionals to use in high density contaminated environment. If you don’t go to hospital with N95, you can keep using it for more than a week.
Medical and surgical masks (3 layers) are enough for public space, but not masks without the layer of meltblown non-woven fabric.
With these tips, you can maximize protection using limited mask resources.