Over the last 40 odd years I have worked around the world in Aluminium Smelter potlines and a clean shaven policy is pretty much the industry standard nowadays. Both disposable masks and respirators are normally fitted by the health and safety guys during your induction and the effectiveness of the seal is tested using a sacharin spray. Not just facial hair but the shape of some peoples faces means that face masks dont always seal properly. Thats probably why they say wearing a mask wont necessarily protect the wearer against coronavirus but it will help in limiting how far it spreads in the air when you exhale.
In a previous life for almost two decades I was in the retail end of aluminium & later helping customers designing their extrusions. I did have a look around the Kurri Kurri smelter a few times.
Basically all face masks are designed to fit the "average" male. So if you are female, tough!
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I wear a white circle beard. I have always either worn a mo or a beard of varying types. In other words never clean shaven.
Unfortunately Richie in some smelters you wouldnt have gotten a job in others they may have offered you with a Racal airstream helmet. Fully enclosed with a motor that pulls air in through a filter, I found them heavy, restricted your vision and in a potline in summer where it could reach 50 or 60 deg. wasnt very pleasant. The policy was introduced in my plant just before I retired so I chose to shave my horseshoe off that I had sported for more than 30 years - I felt like everyone was staring at me (they probably were).