EMS Zones of Care

Emergency Medical Services (EMS) zones of care—Hot, Warm, and Cold—apply to high-risk, dynamic, or tactical incidents involving an ongoing or potential threat. Examples of such incidents include the following: Active shooter incidents: Ongoing or recent gunfire with multiple casualties requiring rapid evacuation and hemorrhage control. Terrorist attacks: Bombings, mass stabbings, or chemical attacks, where the threat may still be active. Hostage situations: Prolonged incidents where law enforcement is securing areas, and medical care must be staged. Explosions or structural collapses: Scenes with secondary hazards such as fire, gas leaks, or unstable structures. Riots and civil unrest: Scenarios requiring responders to work around violent crowds or volatile conditions. Hazardous materials (HAZMAT) incidents: Chemical, biological, or radiological exposures requiring decontamination zones. Mass casualty incidents (MCIs): Large-scale events such as bus crashes, train derailments, or plane crashes in dangerous environments. In the prehospital setting, "zones of care" refer to designated areas defined by varying levels of medical capability and threat exposure. These zones guide the deployment of personnel, equipment, and interventions appropriate to the nature of the incident. Although naming conventions differ among agencies, standardized terminology supports effective interprofessional coordination. The National Incident Management System (NIMS) classifies disaster scenes into Hot, Warm, and Cold zones, each reflecting the relative threat level. Zone designation is based on environmental risk and tactical considerations. The Hot Zone involves immediate danger, where only life-saving interventions—primarily hemorrhage control—are provided. The Warm Zone carries a potential but reduced threat, permitting the delivery of more advanced medical care. The Cold Zone is secure, allowing for full EMS treatment and patient transport. Tactical Combat Casualty Care (TCCC), first developed in the early 1990s, introduced evidence-based guidelines for managing trauma in battlefield conditions. From 2001 to 2015, combat experience in Iraq and Afghanistan significantly shaped TCCC protocols. In 2010, the Committee for Tactical Emergency Casualty Care (TECC) convened to adapt TCCC principles for civilian use. The resulting TECC guidelines, first published in 2011, define 3 dynamic phases of care: Direct Threat Care, Indirect Threat Care, and Evacuation Care. These phases align with the National Incident Management System Hot, Warm, and Cold zones, as outlined in the table below (see National Incident Management System Incident Zones and Their Corresponding Tactical Emergency Casualty Care Phases). Following the 2012 Sandy Hook massacre, national experts gathered in 2013 to improve survival during mass casualty shootings. This initiative led to the Hartford Consensus, a strategic framework spearheaded by the American College of Surgeons Committee on Trauma. The original Hartford Consensus document introduced the acronym THREAT, emphasizing coordinated action through training, policy development, and public education. This acronym is defined as follows: Threat suppression. Hemorrhage control. Rapid extraction to safety. Assessment by medical providers. Transport to definitive care . Zones of care are defined based on various factors, including the nature of the emergency, the presence of HAZMAT compounds, and whether weapons of mass destruction are involved. Each of the 3 primary zones—Hot (Red), Warm (Yellow), and Cold (Green)—has specific characteristics and treatment protocols. Tactical care guidelines used by many local, state, and national EMS units are largely based on recommendations from TECC. The following sections describe EMS interventions based on the zone of care.