Flammable, non-flammable, non-toxic, toxic gases

Division 2.1 Flammable gases
Examples include butane, propane, acetylene, hydrogen

Division 2.2 Non-flammable, non-toxic gases
Examples include oxygen, liquid nitrogen, compressed air, helium, carbon dioxide, and argon.

Division 2.3 Toxic gases
Examples include chlorine, hydrogen sulfide, sulfur dioxide, bromine chloride, and carbon monoxide.