Now, there's no reason to head for the bomb shelters because someone mentioned propane. In the right mixture it is explosive, but so is just about anything. It is, at least, far less corrosive than air!

Personally I would choose butane. Heavier, lower boiling point, somewhat less explosive, and easily available in the form of camper's gas, or single-use cigarette lighters. You can protect an unbelievable lot of chemicals with the gas from one single giveaway lighter, especially if you find a company with a huge stock of now-politically-incorrect advertising material

I smoke, so I always have one nearby