Analyze an SDS

DOT Division 2.3: Poison Gas

Division 2.3 is the DOT division for poison gases: gases that are known to be toxic to humans, or presumed toxic based on animal tests, in such small concentrations that they pose a hazard to health during transport. They are also known as toxic inhalation hazard (TIH) or poison inhalation hazard (PIH) gases.

How it is defined

  • Classification is based on toxicity by inhalation (LC50) from human experience or laboratory tests.
  • Poison gases are assigned a hazard zone from A (most toxic) to D (least) that sets packaging and placarding details.
  • Some Division 2.3 gases are also flammable, corrosive or oxidizing and carry subsidiary labels.

Summary of 49 CFR Parts 171 to 180. The regulations and the Hazardous Materials Table (49 CFR 172.101) control any shipment.

Label and placard

Colors
White background, black symbol
Symbol
Skull and crossbones

A white diamond label and placard with a skull and crossbones and the number 2. The word POISON GAS or INHALATION HAZARD may be required on the placard or package.

Packing groups

None. Division 2.3 uses hazard zones A to D, not packing groups. How packing groups work.

Common examples

  • Chlorine
  • Carbon monoxide
  • Hydrogen sulfide
  • Phosgene

How it relates to GHS

Toxic gases are classified under GHS acute toxicity by inhalation (Categories 1 to 3 are the most toxic) and shown with the skull and crossbones pictogram (GHS06).

DOT classes and GHS classes are assigned under different rules, so a product can have different severity labels in each. See also all GHS hazard classes.

Safe handling reminders

  • Use gas detection, ventilated cabinets and leak response plans.
  • Respiratory protection and emergency escape equipment are often required.
  • Check the SDS for exposure limits and first aid, and notify emergency planners of large quantities.

Where to find it on an SDS

Section 14 shows Class 2, Division 2.3, a UN number, the hazard zone and often the ERG guide number. Look in Section 14: Transport information. Hazard classification for the workplace is in Section 2. You can also see how a UN number points to a response guide on the UN and NA numbers page.

Frequently asked questions

What is a Division 2.3 gas?

A Division 2.3 gas is a DOT poison gas: a gas that is toxic to humans by inhalation at low concentrations. It ships with a white skull and crossbones label.

General reference only. It does not replace the supplier's SDS or the current federal regulations.