If a cargo tank has not been certified as gas free, __________.

Correct Answer: Option D — breathing apparatus should always be used

OSHA and USCG confined space entry regulations (29 CFR 1915) mandate that any space not certified gas-free must be treated as immediately dangerous to life and health. Self-contained breathing apparatus (SCBA) is required to protect personnel from toxic vapors or oxygen-deficient atmospheres, regardless of the intended duration of entry.