Machine shops are pretty clean. The noise is kept mostly in the building. They use just electricity for power. There’s no real chemicals in use. Any spot welding or forging can be done with induction forges. Trucks bringing material and shipping out is noise and pollution, but no different than a grocery store.

There is no clean living but a build up of filth is a sign of someone not doing their job properly. The problem isnt clean vs dirty industry, truly it is all dirty, the problem is outsourcing clean up or consequences for a lack of clean up to the public.