- Air Transportation. Mailable hazardous materials eligible for air transportation must be sent as Priority Mail Express, Priority Mail, First-Class Mail, or First-Class Package Service, 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 as Priority Mail Express, Priority Mail, First-Class Mail, or First-Class Package Service.
- Surface Transportation. All mailable hazardous materials eligible to be sent as Standard Mail, USPS Retail Ground, Parcel Select, or Package Services must be prepared under the requirements that apply to surface transportation. A mailpiece containing mailable hazardous material with postage paid at Standard Mail, USPS Retail Ground, Parcel Select, or Package Services prices must not, under any circumstance, be transported on air transportation.
All mailable hazardous materials sent as Priority Mail Express, Priority Mail, First-Class Mail, or First-Class Package Service, must meet the requirements for air transportation. The following types of hazardous materials are always prohibited on air transportation regardless of class of mail:
- 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.
- UN3090 lithium metal batteries (including lithium alloy batteries) and UN3480 lithium-ion batteries (including lithium polymer batteries).
- Materials excluded from air shipment by DOT regulations (49 CFR 100-185) or of the applicable state (country) or air carrier operator variations.