Gases in this division are poisonous if inhaled, are materials that are a gas at 68°F or less with 14.7 psi, have a boiling point of 68°F or less at 14.7 psi, are known to be toxic to humans to the point of posing a hazard to health during transport and, in the absence of adequate data on human toxicity, are presumed to be toxic to humans (based on laboratory animal testing).

Examples include chlorine and methyl bromide. The word “toxic” is synonymous with “poison” in hazardous materials nomenclature.

This class also includes cryogenic gases. Cryogenic gases are defined as a refrigerated, liquefied gas with a boiling point less than -130 °F.