# Chemical under pressure, flammable, toxic, n.o.s. — Postal shipping restrictions by item category

For Chemical under pressure, flammable, toxic, n.o.s., item category is Chemical under pressure, flammable, toxic, n.o.s; carrier is USPS; restriction type is prohibited; scope is domestic mail (air and surface); conditions is Hazard class 2.1, UN3504, packing group not stated; domestic mail air: Prohibited; domestic mail surface: Prohibited, recorded from its source on 2026-08-10.

- **Item category:** Chemical under pressure, flammable, toxic, n.o.s. _(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 2.1, UN3504, packing group not stated; domestic mail air: Prohibited; domestic mail surface: Prohibited _(verified: appears in the quote below)_

## What the source says

> Chemical under pressure, flammable, toxic, n.o.s. 2.1 UN3504 Prohibited 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/).