As sad as this sounds, if they arrived via the tarmac, I can see the jetway/airplane being one "zone", and the tarmac being another "zone" ("sterile" vs. "safe"?). Then again, given the tools and instruments that is part of their job... huh!

At DTW, I've seen the fire/safety (in full gear, coats and boxes) in the terminal, presumably to respond to a pax issue in the terminal. I couldn't imagine that they wouldn't have something such as a SIDA badge, so they can cross in/out as required.

If we're worried about fire/safety passing something to pax, we have bigger fish to fry.