Abstract: On April 23, 2019, five employees were working at a firm engaged in electroplating, plating, polishing, anodizing, and coloring metals. Employees #1, #3, #4, and #5 were in management and administration. Employee #2 was an engineer. Other workers at the facility were cleaning the electroless nickel plating tank. The tank was drained of the plating solution, and nitric acid was pumped into the tank to clean the walls of the tank. The tank's heat exchanger was left turned on, and it began heating the nitric acid. When orange/yellow smoke was observed coming out of the air scrubber's release stack, the condition was reported to management. Management went to the electroless plating line and observed that the D-12 tank was filled with nitric acid, and that the tank was being heated. As the nitric acid overheated, it released an orange/yellow smoke into the air of the plant. Management evacuated the building of unnecessary personnel. Six managers performed an emergency response and worked to cool the tank and liquid. After the tank and liquid were cooled, one manager began feeling tightness in his chest. He was taken to the hospital, and he was admitted. After work hours, the five other managers began experiencing adverse health effects (respiratory). These five managers were taken to the hospital, and four of the five managers were admitted. They had suffered respiratory tract burns, caused by chemical inhalation, that of nitric acid.