Abstract: On May 21, 2011, Employee #1, a security guard, was having difficulties with breathing and began experiencing respiratory distress while working at a guardhouse station. She was transported to a medical center, where she was hospitalized for treatment. Employee #1 was exposed to a ventilation system that was not working properly in the guardhouse that started in late January. The ventilation system was leaking liquid profusely. The cumulative effects of improper ventilation system for the past five months may have caused her respiratory distress on May 21, 2011. At the time of the inspection on June 3, 2011, the ventilation system in the guardhouse was brand new and working properly. The employer completely replaced its ventilation system prior to the first day of the inspection June 3, 2011.