Over 300 people died in an explosion on March 18, 1937 in a New London, Texas public school building. The natural gas that was being delivered to the school building was not odorized. At that time the natural gas was odorless, and there wasnt a law on record to mandate Odorization. As a direct result of this incident the United State Government passed a law that the chemical Mercaptan be put into natural gas to give it an identifying smell. Odorization requirements