Wear your facemask, goggles and ear protection when cutting the wood.
There is the possibility that incorrectly assembled respiratory therapy devices connected to a tight fitting facemask could also be a hazard.
That would be the facemask -- a hard steel cage that protects the face from impacts.
The regulator mouthpiece passed through a hole in the center of the facemask.
Another experimental device is a facemask that provides resistance when the individual inhales but not during exhalation.