3.4. Site Localization of Decontamination

Appropriate scene management is fundamental to ensuring the safety of both responders and the public in a chemical release incident, and for reducing the potential for contamination spread, especially in emergency situations.

First responders should have emergency guidance available such as that provided in the Department of Transportation (DoT) Emergency Response Guidebook (ERG), as well as the chemical hazard information provided to LEPCs and TEPCs under EPCRA to minimize their risks when responding to an emergency.

Hazardous Materials Response Team personnel are trained to operate safely within the release area and respond to control the release, contain the incident, determine additional courses of action, initiate survivor rescue, and conduct initial cleanup or neutralization of the incident site. Such teams will establish three control zones at the scene of the chemical release: the hot zone, the warm zone, and the cold zone.25,59,60 These zones will both help protect personnel from contamination and reduce its accidental spread by delineating where on the site different types of operations will occur and controlling the flow of personnel between them. Delineation of these three zones should be based on sampling and monitoring results and on an evaluation of potential routes of contaminant dispersion in the event of a release.

  • The hot zone (red zone, exclusion zone) is the area immediately surrounding the incident site in which primary contamination may occur. The zone extends far enough to prevent the primary contamination of persons and equipment/ materials outside the zone. In general, evacuation – but not decontamination or patient care – is carried out in this zone (with certain exceptions). The primary activities performed in the hot zone are site characterization and cleanup work, and some monitoring activities. Access Control Points should be established at the periphery of the hot zone to regulate the flow of personnel and equipment between the hot and warm zones.
  • The warm zone (yellow zone, contamination reduction zone) surrounds the hot zone and contains the area where survivors and responding team members and their equipment are decontaminated. Survivor treatment may be initiated here. The warm zone is designed to reduce the probability that the cold zone will become contaminated by putting distance between the hot and cold zones. Further, the warm zone controls the transfer of workers and equipment into clean areas, again via Access Control Points; any potentially contaminated clothing, equipment, or sample must remain in the warm zone until decontaminated. The decontamination plan should be developed (as part of the Site Safety Plan) and set up before any personnel or equipment enter areas where the potential for exposure to contamination exists; it should be revised if PPE, equipment, or site conditions change, or if site hazards are reassessed based on new information.
  • The cold zone (green zone, support zone) is the uncontaminated area beyond the warm zone in which resources are assembled to support the response. No protective gear should be needed within this zone, and any function that need not or cannot be performed in a hazardous or potentially hazardous area is performed here. The incident command center is usually in the cold zone. In addition, there is greater ability to provide patient care here.

Before any responders enter hot zones, emergency medical responders trained in the recognition of signs and symptoms caused by hazardous materials intoxications and the delivery of antidotes/medical countermeasures should be on-scene and with appropriate resuscitative equipment/MCMs.

Moreover, responders must have personal protective clothing and equipment (PPE) that shields or isolates them from the chemical, physical, and biological hazards that may be encountered, minimizing their exposures. The type of PPE required will depend on the characteristics and amount of the chemical agent involved (e.g., volatility, persistence, inhalational risk, etc.), as different types of PPE provide different levels of respiratory and skin protection. Healthcare professionals, first response and volunteer personnel, veterinary personnel, and environmental sampling personnel may all be issued PPE during a chemical incident.

OSHA Levels of PPE61

  • Level A (the highest level) is a self-contained breathing apparatus (SCBA) worn under a vapor-protective, fully encapsulated, airtight, chemical-resistant suit.
  • Level B is a positive-pressure supplied-air respirator with an escape SCBA worn under a hooded, splash-protective, chemical-resistant suit.
  • Level C is an air-purifying respirator worn with a hooded, splash-protective, chemical-resistant suit.
  • Level D (the lowest level) is a regular work uniform that offers no protection


25. U.S. Department of Agriculture. (2020, June 2). Animal Health Surveillance in the United States. Animal and Plant Health Inspection Service Veterinary Services. ;

59. U.S Coast Guard. (2005). Hazardous Materials Response Special Teams Capabilities and Contact Handbook.

60. U.S. Department of Labor. Occupational Safety and Health Standards Compliance Guidelines Hazardous Materials. e-CFR, § 1910. 120 App B.

61. Sorensen, J. H., Shumpter. B., & Vogt, B. (2002, August 30). Planning  Protective  Action  Decision-Making: Evacuate or Shelter-in-Place. Report ORNL/TM-2002/144. ; Federal Emergency Management Agency. (2019, March). Chemical Stockpile Emergency Preparedness Program, Program Guidebook. U.S. Department of the Army.

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