Thank you for your observation & remarks !
Hence, it would better for him NOT to wear a mask. The mask has rendered him no beneficial effect, but giving him a sense of false security. If we are not breathing effectively through our nose, we will have to breathe through our mouth. In fact, it is worse because the nose is an additional barrier/filter to prevent germs & nasty dust particles from getting into our respiratory system,i.e., lungs. Maybe, once a while, it is alright with/without a mask. But if he is doing this on a long-term basis, it may not be good in a dusty environment. Btw, masks do come in different grades to be worn for protection for different situations.
That's why I said this nicely taken photo IS a GREAT educational tool !
Thanks for the opportunity to share.
Regards,
Victor Ho (Dr)