(a) Each transport vehicle, freight container, portable tank, unit load device, or rail car that contains a poisonous material subject to the ‘‘Poison Inhalation Hazard'' shipping description of § 172.203(m) must be placarded with a POISON INHALATION HAZARD or POISON GAS placard, as appropriate, on each side and each end, in addition to any other placard required for that material in § 172.504. Duplication of the POISON INHALATION HAZARD or POISON GAS placard is not required.