Author(s): Kathleen Robinson. Published on September 1, 2010.

A deadly 1937 school explosion led to odorization requirements for combustible gas

NFPA Journal®, September/October 2010

With few exceptions, the U.S. Code of Federal Regulations requires that "a combustible gas in a distribution line must contain a natural odorant or be odorized so that, at a concentration in air of one-fifth of the lower explosive limit, the gas is readily detectable by a person with a normal sense of smell."

The impetus for this law was the worst school disaster in the nation’s history. Sometime after 3 p.m. on March 18, 1937, approximately 300 people, mostly children, died when natural gas leaking from a pipeline at the London Consolidated School in New London, Texas, ignited and destroyed the building. According to The New York Times the following day, eyewitnesses heard "a muffled sound and a rumbling noise just before the building began to disintegrate. First the walls seemed to bulge out…then the roof lifted up and crashed in with a deafening roar, carrying most of the sidewalls with it."

One witness told a Times reporter that "the explosion sent children hurtling through the air ‘like rag dolls with their clothes torn off.’" About 1,500 students were enrolled in the school, built in 1932, but only 650 or so were in the building at the time of the explosion. Most of the younger children had been dismissed shortly before the disaster occurred.

An investigtion found that the explosion was due to "leaking gas from a pipe or pipes under the building" and that ignition was from the "spark of an electric switch in the manual training room," according to, the website of The London Museum, which is dedicated to educating people about the tragedy.

The school’s original design called for a boiler and steam heating system, but the school board decided to install 72 gas heaters instead. Gas for the heaters was originally supplied by the United Gas Company, but the board decided in January 1937 to connect to a residue gas line from the Parade Gasoline Company. Residue gas, a byproduct of the gasoline-making process, was usually burned off, but many schools, churches, and homes in the area tapped into the residue lines for their own use. The gas was odorless, and the leak went undetected.

After the disaster, Texas passed the first comprehensive state law regulating the odorization of gas, and other states soon followed. The first federal standard for pipeline gas odorization was enacted in 1970, the first federal law regulating pipelines in the United States.

— Kathleen Robinson