The hazard
Confined spaces can look harmless from the outside. The air inside can be short on oxygen or hold toxic or flammable gas you may not see or smell, and loose material like sand or grain can bury a worker. When someone goes down, the natural reaction is to rush in and help, and that can turn one victim into two.
The action
If an entrant collapses, every instinct says go in after them. Without the right training, air supply and equipment, you can become the next victim. In construction, confined space training must teach workers who are not authorized to do entry rescues about the dangers of trying one. Call for rescue, use the retrieval line from outside if one is rigged, and keep everyone else out. (29 CFR 1926.1207(a))
ASK THE CREW
Who on this crew is trained as an entrant, an attendant or an entry supervisor?
From the talk: Confined spaces. Read it in full, free, with the questions and the sign-in sheet.