Dumb tradesmen

Hello all, mature aged (26) aspiring electrician here and I recently did some work experience. I had encountered something that is currently stressing me out. The tradesmen I was with was installing an aircon and he was drilling a hole in the wall and realised he was probably drilling into asbestos. He stopped for a bit told me to go outside and continued drilling. This scared the shit out of me, as I know how nasty the stuff is. How often do you see stuff like this? It really freaked me out tbh and I have been unsettled for a few days and can’t get it off my mind. How can I stop stressing? And what type of dumb thing have you seen in your time? thanks.