The anesthetic gases and vapors that leak into the surrounding room during medical procedures are considered waste anesthetic gases. Health care professionals who work in hospitals, operating rooms, dental offices and veterinary clinics, are potentially exposed to waste anesthetic gases and are at risk of occupational illness. The waste anesthetic gases and vapors of concern are nitrous oxide and halogenated agents (vapors) such as halothane, enflurane, isoflurane, and desflurane. Some potential effects of exposure to waste anesthetic gases are nausea, dizziness, headaches, fatigue, and irritability, as well as sterility, miscarriages, birth defects, cancer, and liver and kidney disease, among operating room staff or their spouses (in the case of miscarriages and birth defects). Employers and employees should be aware of the potential effects and be advised to take appropriate precautions.