Abstract: At approximately 9:30 a.m. on July 23, 2002, a business that manufactured aerospace parts by drop hammer forging was the site of a reddish toxic cloud. Aluminum alloy parts had been placed in a nitric acid solution bath for cleaning. According to the company's internal report, a thermostat device on the tank failed, causing the tank to operate at a temperature higher than required. The lab results of the aluminum parts revealed that the alloy had a slightly higher copper content than normal and that being combined with the high temperature of the nitric acid bath caused the toxic cloud to be released into the atmosphere. There were no employees injured as a result of the accident.