[Chewbacca]

I would ask Mark why he wasn't wearing his goggles and determine mitigating circumstances.

After listening to an explaination. I would explain to Mark that he is in violation of policy for a second time within 2 months and ask him if he knows the consequences of that.

I would then relieve Mark from duty and give him a unpaid 3-5 day suspension.

I would weigh Marks contribution to the team vs the risk of future infractions and then decide if his release from work should stay temporary or become permanent.

Some form of serious consequences are in order- for sure. A suspension sends a clear messages, but also leave the door open for Mark's long term contribution to the team.