The presence of hazardous materials or toxic chemicals at an incident location or other emergency situation adds a new dimension of risk to those handling and treating casualties. The fundamental difference between a hazardous materials incident and other emergencies is the potential for acute risk from contamination to both patient and responder. In some cases, traditional practices must be altered to avoid compounding a critical situation. Hospital emergency departments must protect their personnel and other people within the hospital, while providing the best care for the chemically contaminated patient. This guide is intended to help hospital emergency departments plan for incidents that involve hazardous materials and to improve their ability to respond to these incidents. To ensure appropriate and timely patient care, as well as optimal worker protection, emergency personnel must understand decontamination procedures and personal protective equipment, neither of which are routinely covered in the course of their professional training. They should also be aware of community resources that could be called upon to assist with an emergency response. Current training curricula for emergency room physicians and nurses and emergency medical technicians (EMTs) often do not adequately prepare these professionals to manage the contaminated individual or to decontaminate patients exposed to toxic substances. Accurate, specific, and concise guidance is needed to describe appropriate procedures to be followed by emergency medical personnel to safely care for a patient, as well as to protect equipment, hospital personnel, patients, and others from risk of secondary exposure. In response to this need, the Agency for Toxic Substances and Disease Registry (ATSDR) contracted for the production of a three-volume series entitled Managing Hazardous Materials Incidents: I. Emergency Medical Services: A Planning Guide for the Management of Contaminated Patients; II. Hospital Emergency Departments: A Planning Guide for the Management of Contaminated Patients; and III. Medical Management Guidelines for Acute Chemical Exposures. The first document is designed for use by emergency medical technicians and other prehospital care providers to minimize their risks of exposure during the prehospital period and to provide for the safe and effective treatment of chemically contaminated patients. This volume, written for emergency department personnel, is designed to familiarize readers with the concepts, terminology, and key operational considerations that affect the management of incidents of chemical contamination. It presents uniform guidance for the emergency care of chemically contaminated patients; provides basic information critical to advance planning and implementation of emergency medical strategies; illustrates the characteristics of hazardous materials incidents that compel modifications to traditional emergency response procedures; and presents effective preparatory response actions. Not all hospital and community emergency response systems are prepared to respond to a hazardous chemical incident to the same degree. This document may be used to assess a hospital s capabilities with respect to potential community hazards and to develop response plans using national and community-specific resources. Employee safety and training are also key factors in the effective management of medical emergencies. This document also is intended to provide source material for developing local training and safety protocols.