# Oxygen generator, chemical, spent — Postal shipping restrictions by item category For Oxygen generator, chemical, spent, carrier is USPS; restriction type is prohibited; scope is domestic mail (air and surface); conditions is Hazard class 9, NA3356, packing group III; domestic mail air: Prohibited; domestic mail surface: Prohibited, recorded from its source on 2026-08-10. - **Item category:** Oxygen generator, chemical, spent _(verified: appears in the quote below)_ - **Carrier:** USPS _(our reading, not quoted from the source)_ - **Restriction type:** prohibited _(our reading, not quoted from the source)_ - **Scope:** domestic mail (air and surface) _(our reading, not quoted from the source)_ - **Conditions:** Hazard class 9, NA3356, packing group III; domestic mail air: Prohibited; domestic mail surface: Prohibited _(verified: appears in the quote below)_ ## What the source says > Oxygen generator, chemical, spent 9 NA3356 III Prohibited Prohibited ## Source - https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf Last verified: 2026-08-10. Review by: 2027-08-10. Part of [Postal shipping restrictions by item category](https://referencesource.org/shipping-restrictions-by-class/).