In shortage situations, one mask reused properly is better than no mask.

I work at a medical center in Korea and we are under the following instructions:

1. Place masks for reuse in a specific place to avoid cross contamination. 2. Treat the outside of the mask as contaminated. Don't touch. 3. Wash hands after wearing a reused mask. 4. Throw out masks if they get wet, damaged, or (N95 only) folded.