When legitimately wearing a mask, there are 3 situations:

1. Protecting the environment from you (e.g. surgical): you sneeze into the mask, then replace the mask away from the environment.
2. Protecting you from the environment, non-life-threatening (e.g. sandblasting, painting, etc): pull off mask to sneeze, put mask back before breathing in if you can, clear mask by blowing. (Mask trained people will often follow protocol for #1).
3. Protecting you from the environment, life-threatening (e.g. deadly chemicals): sneeze into mask, bitch, Charley Mike.
4. Virtue signaling: don't wear a mask, sneeze into your elbow or use a tissue.