Many aerosol sprays use propane as the propellant.
To replace the nonflammable Freon.
Congress in its infinite whizdumb has mandated that methane be used in all new refrigerators and air conditioners.
What could possibly go wrong?
Oh, did I mention that for those applications, the gas must be unodorized?
Quite the boon for my old company that makes methane sensors, and potentially quite the boom for those who don't buy them...