Abstract: On September 3, 2013, Employee #'s 1, 2, 3, 4, 5, and 6 were remodeling portions of a building interior to accommodate a new tenant. The project required relocating and abandoning septic lines in the slab foundation. The employees cut approximately 45 ft of concrete using a Husqvarna K-750 2-stroke gasoline powered quick cut saw equipped with water spray for silica dust suppression to prosecute the cutting. Between 9:00 - 9:30 a.m. the employees were complaining of odors, a haze in the lobby and were experiencing eye irritation, headaches, nausea, blurred vision, coughing and vomiting. Conditions worsened and a coworker called the DOSH in Fresno, and was informed they may have exposure to carbon monoxide (CO). The Clovis Fire Department was contacted for assistance to test the air for CO. The Clovis Fire Department evacuated the building and begins triage and treatment for CO exposure. After approximately two hours post arrival CO concentration was measured using a Draegar 4-Gas meter: less than or equal to 5 ppm in PP work area; 8 ppm in the common areas and construction area; 21 ppm highest reading in the construction area. Employees #1, 2, 3, 4, 5, and 6 were transported to two Acute Care hospitals, where they were treated for the exhaust fume containing CO exposure to their face, and lungs. The employees were later released.