National Archives and Records Service film-vault fire at Suitland, Md. : hearings before a subcommittee of the Committee on Government Operations, House of Representatives, Ninety-sixth Congress, first session, June 19 and 21, 1979 (1979)

477 number of witnesses and reported in the Prince Georges County Fire Department fire investigation report, although they chose to ignore it in order to place the origin in a closed, undisturbed vault; a more reasonable location for spontaneous ignition. The committee found that most probable cause was connected to the work in progress because of the location, the open vault, and the hazards introduced. Also, the cause did not involve direct ignition of film, as nitrate film fires develop rapidly, in seconds, but the fire did not involve nitrate film until 15-20 minutes after work stopped. This factor strongly suggested that cardboard boxes, present in the vaults, were involved in the fire cause. Burned cardboard was present in the debris. Cardboard could have been ignited by several mechanisms present, could have smouldered for a while, burst into flame and heated film in cans to ignition. Cardboard could have been ignited by a cigarette or cigar discarded or forgotten. It could also have been ignited by a hot chip of reinforcing steel, or by an overheated drill, as discussed. Arson, although possible, is improbable. The committee determined that the most likely chain of events was that cardboard was ignited in a vault by