Isobutane

Isobutane (2-methylpropane) is a four-carbon branched alkane gas used as an aerosol propellant alongside propane and n-butane. It is interchangeable with butane in most formulations and shares the same H220 (extremely flammable gas) + H280 (gas under pressure) classification — fire hazard only, no inhalation toxicity beyond simple asphyxiation at very high concentrations. Not on Prop 65, not an asthmagen, not a sensitizer, not aquatic-toxic. Disperses as a gas immediately on release. The danger profile is identical to propane and butane — fire and explosion, not chronic toxicity. EPA and CARB classify isobutane as VOC-exempt for aerosol propellant use.