Good guesses, one and all.
The men are a roofing crew working 60 feet up in
the air over a chemical reaction chamber at a
pharmaceutical plant.
They are installing a new layer of lightweight, insulating
concrete (40# per CF vrs 145# standard). The L.W.I.C. is a
base layer for a new 220 mph wind resistant hurricane roof.
The photo is 10% of total project size.
I used to enjoy "What's my line" as a kid.
d