Let me clarify my earlier statement.
You can use a PAC on stainless, but the airborne Hex Chrome is about 30 micrograms per cubic meter. This is 6 times the PEL. Even in a respirator, you would have to track the hours of exposure, take air samples, use HEPA ventillation, have medical evaluations done .... yada, yada, yada.
Lately, TIG welding is the only weld process that doesn't allow for the oxydation of Chromium to Cr-VI. Maybe dual-shield flux core as well, but I haven't looked into that yet. SMAW (stick) welding is almost as bad as the plasma arc cutting according to the air samples I have seen.
Since they lowered the PEL from 50 to 5 ug/m3, the world of stainless work has gotten a lot harder to navigate.