Skunk oil is added to natural gas so it easily detected long before it is at dangerous levels. Gas explosions were common 80 years ago, but they are rare now.
They call it Mercaptan here. One year a utility near by added way too much to the natural gas pipeline and had to go around with gas detectors because people who didn’t smell gas in their house before suddenly did.
We had one down the street about 15 years ago. Townhomes. People buy them, turn the key, know nothing about the mechanics of the construction, and are out of the house most of the time except to sleep or maybe eat something first. Because the row was fairly recently built, this particular unit had settled in such a way that one of the gas lines developed a crack and was faintly hissing. By the time the homeowner noticed a crack in the foundation wall, the place was almost ready to blow the whole block to kingdom come.