Flammable nitrocellulose X-ray film ignited in a basement storage room, emitting a poisonous yellowish-brown gas which spread throughout much of the Clinic and subsequently exploded several times.

The burning nitrocellulose X-ray films quickly produced a significant amount of poisonous gas which spread throughout much of the building via the pipe chases which connected to the neighboring mechanical room.

Later chemical analysis suggested the victims inhaled phosgene, carbon monoxide, nitric oxide, and methyl chloride, all generated by the smoldering films.

The force of the explosion sent the vapors throughout the clinic, but also provided a large opening in the center of the building which allowed the toxic gas to escape.

It was not until the second large explosion blew out the skylight, and the gas began to dissipate, that the fire companies realized how many people were still in the building.

[8] The four story original clinic building, the site of so much disaster, though literally overshadowed by many newer surrounding hospital and research facilities, still stands.

[1] Nationally, the disaster prompted medical facilities to establish standards for the storage of nitrocellulose film and other hazardous materials.

Nevertheless, most of the deaths were from breathing carbon monoxide and nitric oxide rather than methyl chloride itself, and even at the time of the disaster chemical companies were aware of the hazards of existing refrigerants.