[mirimir]

Fun factoid: Propane leaks are far more dangerous than methane leaks. Methane is less dense than air, so it tends to mix more fully. But propane is more dense than air, so it tends to pool near the floor. And the lower flammability limit for propane is lower (2.1% vs 5.0%). So you reach the lower flammability limit faster. Plus the fact that pilot lights are often near the floor.