Early in 1937, the New London school board, in order to save money, cancelled their natural gas contract. Instead, plumbers installed a tap into a residual gas line associated with oil production. This practice, while not explicitly authorized by local oil companies, was widespread in the area. The natural gas extracted with the oil was seen as a waste product and thus was flared off.
Natural gas, which is odorless and therefore undetectable to the human nose, had been leaking from the connection to the residual line. The gas had built up inside an enclosed crawlspace that ran the entire length of the school building. Students had been complaining of headaches for some time, but little attention was paid.
For more go to Odorization: simply a matter of safety. (natural gas)(Brief article). Pipeline & Gas Journal 233.11 (Nov 2006): p50(1). http://www.oildompublishing.