Abstract: Employee #1, age 18, was working on the second floor of a house under construction while two heaters were operating on the first floor. The only door or window open in the entire house was the one leading to the garage. After working in the house for approximately two hours, Employee #1 came downstairs complaining that he did not feel well, and he went out to lie down in the work van. About 30 minutes later, he was found there, unconscious. Employee #1 was transported to the hospital, where he died. The medical examiner determined the cause of death to be carbon monoxide poisoning. Two coworkers in the building did not become sick.