• Shipments of materials that are poisonous by inhalation must conform to special marking and placarding requirements.
• Marking requirements for poison by inhalation materials depend on the type of packaging.
• The exception is anhydrous ammonia, which only needs to be marked with “Inhalation Hazard.”

Because of the danger of transporting poison inhalation hazard materials, the Hazardous Materials Regulations (HMR) have special requirements for shipments of materials meeting the definition of Material Poisonous by Inhalation (171.8). If a material meets the criteria for an inhalation hazard, whether listed in the Hazardous Materials Table (HMT) or not, it is subject to the requirements.

There are several things to be aware of when transporting poison inhalation hazard materials.

Shipping papers

For materials that are poisonous by inhalation, the words “Poison-Inhalation Hazard” must be entered on the paper immediately after the shipping description. For gases, “Zone A,” “Zone B,” “Zone C,” or “Zone D” must be included, and for liquids, “Zone A” or “Zone B,” as appropriate. (For anhydrous ammonia, see “Exceptions” section below).

Markings for non-bulk packages

A non-bulk package that contains material that is poisonous by inhalation must be marked “Inhalation Hazard” in association with the required labels or proper shipping name. The inhalation hazard marking is not required if the package bears a poison gas or poison inhalation hazard label displaying the words “inhalation hazard.”

Markings for large quantities of non-bulk packaging

A transport vehicle or freight container must be marked with the identification number specified for the material, on each side and each end, if the following apply:

• It was loaded at one loading facility.
• It contains at least 1,000 kg (2,205 lb) of non-bulk packages containing a material poisonous by inhalation (in Hazard Zone A or B).
• These packages all have the same shipping name and identification number.

If the transport vehicle or freight container contains more than one inhalation hazard material that meets the above identification number marking requirement, it must be marked with the identification number for only one material. That one identification number is determined by the following:

• For different materials in the same hazard zone, the identification number of the material having the greatest aggregate gross weight.
• For materials in both Hazard Zone A or B, the identification number for the Hazard Zone A material.

Markings for bulk packages

A bulk package that contains material poisonous by inhalation must be marked “Inhalation Hazard” in association with the required labels or placards or the proper shipping name. The inhalation hazard marking is not required if the package bears a poison gas or poison inhalation hazard label or placard displaying the words “Inhalation Hazard.”

Bulk packaging must be marked on two opposing sides with the Inhalation Hazard marking. The marking must meet the following size requirements:

• For rail cars: Have a width of at least 6.0 mm (0.24 in) and a height of at least 100 mm (3.9 in);
• For portable tanks with capacities of less than 3,785 L (1,000 gal) and intermediate bulk containers: Have a width of at least 4.0 mm (0.16 in) and a height of at least 25 mm (1.0 in); and
• For cargo tanks and other bulk packaging: Have a width of at least 6.0 mm (0.24 in) and a height of at least 50 mm (2.0 in).

Placards

Any vehicle, freight container, tank, or unit load device that contains a poison inhalation hazard material must be placarded on each side and each end with a “POISON INHALATION HAZARD” or “POISON GAS” placard, as appropriate, in addition to any other required placard.

Exemptions

Anhydrous ammonia transported within the U.S. is treated differently than other poison inhalation hazard materials. Only the words “Inhalation Hazard” must be entered on the shipping paper in association with the shipping description. The requirements in 172.203(m) do not apply.

Non-bulk packages must be marked “Inhalation Hazard” in association with the shipping name and identification number. Bulk packages must be marked with “Inhalation Hazard” on two opposing sides. The subsidiary placarding requirements in 172.505 are not required.