I was glancing at it and saw propane. The first thing that came to my mind was the grill on my porch that uses propane. Please explain the significance of this ingredient (flammable, bad for the hair, etc.).
Isobutane & Propane are the propellants that make the mousse come out of the can and 'Foam-Up'. YES they are Flammable and the can should say so, but you have nothing to worry about unless you style your hair over an open flame the propellants evaporate almost immediately and after a few minutes you can use heated appliances.