The Cleveland Clinic Foundation was founded by several doctors in Cleveland, Ohio after the close of World War I. The Foundation operated out of multiple buildings in the area including a hospital and clinic. The clinic building was used primarily for examination and diagnosis of patients, and also included staff offices, laboratories, a staff library, and the x-ray department. One of the important diagnostic tools employed by the clinic was x-rays, which were stored in the basement.
Nitrocellulose film, used as x-ray film at the clinic, is flammable and when burned, produces dangerous gases which are poisonous and explosive. The film becomes unstable at high temperatures and can begin to decompose at temperatures near 300 degrees Fahrenheit. By 1929, the hazards of nitrocellulose film were known, and alternative "safety" cellulose acetate film was growing in use. Guidance from NFPA was first published in 1925 for nitrocellulose film and x-ray storage and handling. NFPA recommended safety measures at the time included vented storage and protection by automatic sprinklers.
At the clinic, the film was stored in the basement, in an old coal bin, and was not stored in compliance with NFPA guidance. It is estimated that approximately 70,000 x-rays, weighing between 3 and 4 tons, were stored in this room. Running through the room, near the ceiling, were steam pipes. Pendant lights were also located near the ceiling in the film storage room. Both the steam pipes and the lights were sources of heat that should have been located a safer distance from the film storage.
The morning of May 15, a steamfitter reported to the clinic to fix a leak reported in the film room. When he arrived, he attempted, but was unable to locate the leak. He did make note that the room was overheated. The steamfitter returned to the room several hours later to find the room filled with steam, and instructed that the steam supply be shut off. When he returned again to the room about 20 minutes later, he saw a cloud of yellow smoke near the ceiling. He attempted to extinguish a fire, but was unable, and as he made his way to exit the room, he was thrown through the door by the first of two explosions. He was able to get to a window by the time of the second explosion and was blown through the window.
The force of then two explosions pushed toxic gases from the fire through the pipe ducts and distributed fumes throughout the building. Evidence of the spread of gas would later be found in almost every room in the clinic building, as it left a brown residue when it settled on cold surfaces. The fire continued to burn in the film room (pictured at left, after the fire) and an adjacent storage room causing fumes to spread vertically up the back staircase. These ignited as they reached air, burning handrails and baseboards in the staircase. Gases also began to collect in the building attic and approximately ten minutes after the first explosion, a final explosion occurred, collapsing the ceilings of many fourth floor rooms, and blowing out a main skylight in the building.
It is thought that approximately 225 people were in the building at the time of the fire. Some staff were caught by surprise, and found dead at their desks, while others attempted to exit the building, and collapsed, overcome by the fumes on their way to the exit. One hundred twenty two people died as a result of the fire at the clinic, and an additional 50 people were treated for exposure to the fumes. It should be noted that none of the deaths or injuries were as a result of burns, and there was limited fire damage to the structure. It is unknown what started the fire, but was determined that either the heat from a light, or the heat from the steam, could have achieved the temperatures needed to start the decomposition of the nitrocellulose film. It is also of note that within a few years of this incident, nitrate film would be phased out for use in x-rays, being replaced with more stable "safety" cellulose acetate film.
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