Abstract: On Wednesday May 9, 1990, high winds damaged the A.E. Staley plant and resulted in a valve being sheared from a 7,500 gallon tank of sulfur dioxide. Approximately 4,000 gallons were released. Approximately 23 contractors in adjacent areas to the tank had smelled an odor and left the building when it became intolerable. Four contracted employees, Employees #3, #4, #11, and #12, were treated for exposure. Staley Employees #1 and #2 were also treated. Employee #1 was reporting to his supervisor after hearing of the problem from the contractors and Employee #2 was in the recreational facility north of the plant. The evacuation alarm was sounded a few minutes after the contractors evacuated. Employees #5 through #10, fire fighters, were exposed on the road north of the plant while responding. Staley did not permit the fire fighters on the site.