Firing them wouldn't harm them more than letting them destroy their lungs. And PPE requirements are commonly mandatory: you can't set foot in a construction area without a hardhat, no matter who you are.
Depends on the fines. Where I am, simply doing 11+ gets an automatic suspension of your license. When I was in the US, it was a joke in that you had to "get pulled over" to get a fine. Here it is automated all over the place.
It's funny. This discussion keeps getting pulled in different directions. Are you advocating that we automate PPE use in the workforce? Otherwise, what's the point of this comment?