section_path: Safety concerns/Added odor
section_name: Added odor
paragraph_text: Added odor
  
  In its native state, natural gas is colorless and almost odorless. In the US, the New London School explosion that occurred in 1937 in Texas caused a push for legislation requiring the addition of an odorant to assist consumers in detecting leaks. An odorizer with an unpleasant smell, such as thiophane or tert-Butylthiol (t-butyl mercaptan) may be added. Situations have occurred in which an odorant cannot be properly detected by an observer with a normal sense of smell despite being detectable by analytical instruments. This is caused by odor masking, when one odor overpowers the sensation of another. As of 2011, the industry is conducting research on the causes of odor masking.