Not sure, it'll be exempted as 'art' or something. If UFCer A beats UFCer B into a coma it's not an OSHA issue either. FEMA has protocols on testing saferooms. They fire a saboted 2x4 from a compressed air cannon at 200mph. It goes straight through unreinforced concrete block wall. I doubt a helmet is going to do much good in a real flying debris impalement.