The bad odor most people associate with natural gas is not the gas at all; it is Mercaptan, an odorant added to odorless gas.
Once it was not so...until after a tragic East Texas disaster considered the worst known school disaster in history. On March 18, 1937, a natural gas leak built up under the New London school. When ignited by a spark, it blew the school off its foundations. It came back down in a mass of rubble that killed about 300 people -- more than half of the schools' teachers and students.
Not long afterward, the 45th Texas State Legislature enacted House Bill 1017. This bill gave the Railroad Commission "the authority to adopt rules and regulations pertaining to the odorization of natural gas or liquefied petroleum gases," the commission archives states. "On July 27, 1937, Gas Utilities Docket 122 was adopted and the commission began enforcement of odorization requirements for natural gas." An East Texas disaster started a trend in odorizing natural gas that has probably been adopted around the world.
One can stroll many a rural East Texas cemetery and feel the sorrow of a community that lost a number of children in a short span due to some outbreak of disease. A tour of the Pleasant Hill Cemetery -- with tombs of over 100 people who died on the same day -- is a quite eerie experience. A short version of the New London story is HERE. Those who perished are memorialized HERE.