I'm not sure who started the rumor that putting face masks in the microwave kills germs but it simply isn't true. The NH State Fire Marshal's Office released a statement on social media to let people know its a really bad idea. They've included a few photos of masks that are burnt to a crisp.

NH State Fire Marshal's Office via Facebook

Some people need the gentle reminder that masks are made of cloth and cloth catches on fire. Also some of the disposable masks have a metal bridge on the nose and that can spark or even break your microwave! NO BUENO!

To properly sanitize your face mask, your best bet is to wash it with detergent in the washing machine.