For my diploma thesis, I was working in a University department that developed semiconductor manufacturing techniques. Nasty chemicals, gasses, like Arsine and Phosphine. To exchange a lot of things, people had to wear gas masks -- the heavy ones, with their own air canister. Plus, some things there worked with concentrated acids and bases in the same cabinet. To maintain them, people had to wear heavy rubber boots, apron, gloves, gas masks AND full face shield.
At one time, two of those Darth Vader types are cleaning out the scrubber (removes toxic process gasses from the exhaust system). The lab the scrubbers were located in had windows in the doors, as usual. A grad student, who does his academic work on equipment in this lab, looks through the window, sees the guys, AND WALKS IN! :shakehead
I'm not too unhappy that I could not do my PhD thesis at this place. Three months after I left my old supervisor got a whiff of Arsine. He's fine, fortunately, but may develop some early cancer because of it.