Does natural gas rise or fall?

We have an occasional "gas" smell at the base of our internal stairs (we live at the top of them). I'd thought perhaps our appliance pilot lights and or ignition delays were leaking a little and it collected down there. read more

Natural gas (methane) is lighter than air. Natural gas (methane) will rise and diffuse rapidly when it escapes to an open area. The specific gravity of natural gas (methane) is in the range of 0.56, and the specific gravity of air is 1. Lighter-than-air natural gas (methane) should not be confused with liquefied petroleum gas. read more

Natural gas will usually fall toward the floor. Natural gas is heavier than air. If there are winds or breezes, it will dissipate or rise. read more