Abstract: At approximately 6:05 p.m. on August 11, 1999, an employee working as a Level II Operator was seriously burned. The employee was burned by a deflagration of a batch of propylene glycol alginate (PGA), an organic chemical food additive, which had been over dried in a large industrial dryer (dryer #1). The employee sustained first-and-second-degree burns of his face, neck, and upper extremities and was admitted and treated, including skin grafts, at the UCSD Burn Center for several weeks. The resulting fire involved and damaged the dryer system, which included dryer #1, the associated ductwork, cyclone, and baghouse. In the time period prior to the accident the dryer system underwent unusual maintenance procedures. As a result, the PGA within this dryer system had been subjected to extraordinary heating, excessive drying, and directionally-reversed aeration. This extraordinary treatment of the PGA rendered the already combustible product more susceptible to ignition and rapid deflagration. At the moment of the accident the employee had been performing the routine procedure of opening the cleanout port of the dryer and manually pushing the PGA into the fan. This procedure allowed air, supplying oxygen for combustion, to enter the dryer and enflame the already smoldering PGA. The possible accumulation of carbon monoxide that may have been generated from the smoldering PGA within the dryer system may have also played a role in the rapid deflagration.