A research team at the Korea Advanced Institute of Science and Technology, or KAIST, has succeeded in developing a mask that can be reused even after being washed 20 times.
Welcome news in Korea, where there's a severe mask shortage.
The researchers say the nanofiber filter inside the cotton mask, after all the washes, maintained 94 percent of its original effectiveness.
It can be used for more than a month when disinfected with ethanol.
The team say they hope the mask can help solve the shortage as well as the environmental problems caused when masks are thrown away.