An employee was processing scopes in endoscopy. The cycle on the Steris machine finished and all safety checks and indicators completed and passed. The employee opened the lid to remove the scope and noticed some fumes (peracetic acid) coming from the machine. The employee had a burning sensation in the throat and lungs. Other employees assisted the employee out of the room into fresh air. The employee took a break and returned to work, but was having difficulty breathing. She was admitted to the hospital for treatment.