The National Institute for Occupational Safety and Health (NIOSH), in the Centers for Disease Control and Prevention (CDC), conducts research and makes recommendations for the prevention of work-related injury and illness. The NIOSH health hazard evaluation (HHE) program is available for employees, employers, or union representatives to ask our comprehensive team of experts for an investigation of their health and safety concerns by requesting an HHE. Our team contacts the requestor and discusses the problems and how to solve them. This may result in sending the requestor information, referring them to a more appropriate agency, or making a site visit (which may include environmental sampling and medical testing). If we make a site visit, the result is a report of our investigation that includes recommendations specific to any problems found, as well as general guidance for following good occupational health practices. We received a request for an HHE from employees at a general hospital in New York. The request stated that the ventilation in the "STERIS room" in which five employees cleaned and sterilized endoscopes with Klenzyme Enzymatic Cleaner and STERIS(tm) 20 Sterilant Concentrate was possibly inadequate. The employees reported they were experiencing headache, shortness of breath, eye irritation, and diminished sense of smell. We conducted a site visit that included an opening conference, a walk-through of the STERIS endoscope sterilization room, air sampling for peracetic and acetic acids, measuring temperature and humidity, observing airflow patterns in the room using smoke tubes, and confidential interviews with several employees. We asked the employees about possible work-related symptoms, safety and health training, use of personal protective equipment (PPE), chemical exposure incidents, and indoor environmental quality.