What Does USPS® Classify as Hazardous Materials?

If you have questions about the mailability of an item, contact your local Mailing Requirements office via 1-800-ASK-USPS (1-800-275-8777).

You can also find information on common hazardous, restricted and perishable materials in Publication 52, Hazardous, Restricted, and Perishable Mail. These guides identify many items by their common names and can help you determine what may be mailed and if special packaging or other restrictions apply. The guide is completely searchable by keyword and links to more detailed information.

Hazardous materials include any matter having a clear potential for causing harm to the mail, persons, or property involved in moving the mail. However, many commonly used items contain materials that are considered hazardous by U.S. Postal Service standards. Some fuel-containing items commonly found in the mail are:

  • Chainsaws
  • Lawn trimmers and edgers
  • Small motors and engines
  • Used fuel tanks (motorcycles, lawn mowers)
  • Small generators
  • Camp stoves
  • Gas lanterns or lamps
  • Model cars or aircraft

Each of the items listed is potentially mailable but only under one of the following conditions:

  • The item has never contained fuel, or
  • The fuel and all vapors have been completely purged from the item.

    Note: If the item emits a fuel odor or if any residue is present on the outside or inside of the item, then the item is not completely purged.


Items containing fuel or fuel vapors are not mailable under any circumstances. Simply removing the fuel from an item does not make the item acceptable for mailing. Fuel tanks containing only vapors can have a greater explosion risk and thus become more hazardous than tanks that are full or partially full of fuel. The fuel must be removed and all vapors must be purged to allow these items to be safely mailed.

The following is what happens when presenting parcels and/or potentially Hazardous Materials to the Post Office™:

  • At acceptance, Postal employees will ask, “Does this parcel contain anything liquid, fragile, perishable, or potentially hazardous?”
  • Postal employees will look out for parcels with items that could potentially contain fuel and advise mailers of the mailing limitations.
  • When accepting parcels, Postal employees will look for oil or fuel stains on the outside and fuel or petroleum odors.
  • If a mailpiece has markings denoting a flammable or combustible material, Postal employees will verify the contents with the mailer and with available references that all mailability requirements have been met.
  • While handling parcels, if Postal employees encounter a fuel odor, find liquid stains, or hear liquid sounds, they will move the parcel to the HAZMAT storage area or notify their supervisor.

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