Which classification includes gases that are flammable or poisonous?

Gases that are classified as flammable or poisonous fall under Class 2 in the transport of hazardous materials. This classification is specifically designed for gases, which can include both compressed gases and liquefied gases. Within this class, toxic and flammable gases pose significant risks not only due to their potential for combustion but also their ability to cause harm through inhalation or skin exposure.

Class 1 is designated for explosives, which are quite different in nature and risk. Class 3 covers flammable liquids, and while they too present fire hazards, they are not categorized under gases. Class 4 relates to flammable solids, reactive substances, and things like spontaneous combustibles, which again do not pertain to gas classifications. Thus, Class 2 accurately encapsulates the unique hazards associated with gases that are either flammable or poisonous, making it the correct classification in this context.