- Air Transportation. Mailable hazardous materials eligible for air transportation must be sent as Priority Mail Express, Priority Mail, or First–Class Mail, as permitted. Mailpieces must be prepared to meet all requirements that apply to air transportation. Mailpieces must be properly packaged and labeled within DMM requirements and the operator variations of the air carrier. When required, a shipper’s declaration for dangerous goods must be affixed to the outside of the mailpiece. Refer to the Technical Instructions for the Safe Transport of Dangerous Goods by Air of the International Civil Aviation Organization (ICAO) for air carrier operator variations.
Note: Mailable hazardous materials that are prohibited from air transportation may not be sent at Priority Mail Express, Priority Mail, or First–Class Mail rates.
- Surface Transportation. All mailable hazardous materials eligible to be sent at Standard Mail rates must be prepared under the requirements that apply to surface transportation. A mailpiece containing mailable hazardous material with postage paid at a Standard Mail rate must not, under any circumstance, be transported on air transportation.
The following types of hazardous materials are prohibited from transport via aircraft (i.e., at Priority Mail Express, Priority Mail, or First–Class Mail rates) under any circumstances:
- Explosives other than Division 1.4S, small rocket motors, igniters, and safety fuse.
- Anything susceptible to damage or that can become harmful because of changes in temperature or atmospheric pressures unless protected against the effects of such changes.
- Magnetic material that has a field strength sufficient to cause a compass deviation at a distance of 7 feet or more from any point on the outer packaging.
- Flammable materials (gases, liquids, and solids).
- Radioactive materials.
- Hazardous materials excluded from air shipment by the regulations of 49 CFR 100-185, or by the applicable country or air carrier operator variations.