Read the permit before you go in

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

Entry into a permit space is planned on paper first. Before entry begins, the entry supervisor named on the permit must sign it to authorize entry. The permit should show the hazards, the controls, the test results, who is inside and how to call rescue. If what you see does not match the permit, stop. (29 CFR 1926.1205(b))