RED ZONE: Areas where significant contamination with chemical, biological, radiological, or nuclear (CBRN) agents has been confirmed or is strongly suspected but area has not been characterized. The Area is presumed to be life threatening from both skin contact and inhalation.
YELLOW ZONE: Areas where contamination with chemical, biological, radiological, or nuclear (CBRN) agents is possible but active release has ended and initial monitoring exists.
GREEN ZONE: Areas where contamination with chemical, biological, radiological, or nuclear (CBRN) agents is unlikely. This zone covers the area beyond the expected significant dispersal range of the initial event and secondary contamination range caused by traffic and emergency responders.
Recent terrorist events in the United States underscore the importance of emergency response procedures for dealing with terrorist-related events involving chemical, biological, radiological, or nuclear (CBRN) agents. OSHA and NIOSH continue to work with other Federal response agencies to provide accurate, current information to help prepare these on-scene responders.
Emergency response to hazardous substance releases including CBRN are guided under OSHA's Hazardous Waste Operations and Emergency Response (HAZWOPER) Standard (29 CFR 1910.120(q)). Personal protective equipment is selected to meet the requirements of this standard and Subpart I. NIOSH has developed a respiratory protection approval specifically for CBRN exposures and the Department of Homeland Security also adopted guidelines for appropriate PPE. In order to use this guidance effectively, an employer must assess the risk of a hazardous substance release to the emergency responders and base the PPE selection on the level of knowledge relative to that risk. This kind of assessment is a typical safety and health evaluation with the unusual caveats that many of the agents are highly toxic by both skin and inhalation, typical indicators of exposure such as odor, smoke, or fume may not be present, exposure monitoring is difficult for some of the compounds, and there may be a locally limited supply of CBRN-approved respirators for a large response during initial emergency operations. Based on the hazardous substances and conditions known to be present, the Incident Commander in charge of a response shall implement appropriate emergency operations, including selection of appropriate PPE for employees who respond. This includes, at a minimum, PPE meeting the criteria in 29 CFR 1910.156(e) for fire fighting operations beyond the incipient stage, 29 CFR 1910.120(q)(3)(iii).
Site control is an important part of managing any emergency response operation. Some guidance for zoning exists in 29 CFR 1910.120 Appendix C and in the NFPA 471 Standard (2002) (Hot, Warm, Cold) with hot denoting a contaminated area where adverse effects might be seen, warm being an initially clean area for close support and decon, and cold representing an area with no potential exposure. Other guidance from the DOT Emergency Response Guidebook provides for an "Initial Isolation Zone" where dangerous or life threatening concentrations of a substance may exist or a "Protective Action Zone" where serious or irreversible health effects may be seen. The OSHA zones of Red, Yellow, and Green described below are available to be used by incident commanders as complimentary guidance for personal protective equipment selection based on the level of knowledge about the WMD events. The use of the Red, Yellow, and Green zones is not mandatory nor exclusionary of other site control concepts. It is intended to offer flexibility to an incident commander managing a large WMD event within the limitations of current first responder monitoring capabilities.
Areas where significant contamination with chemical, biological, radiological, or nuclear (CBRN) agents has been confirmed or is strongly suspected but area has not been characterized. The Area is presumed to be life threatening from both skin contact and inhalation.
Level A protection is generally needed when the active release is still occurring, or the release has stopped but there is no information about the duration of the release or the airborne concentrations of CBRN agents. Respirators chosen initially for responders going into a known release area where CBRN are suspected should be a positive pressure self contained breathing apparatus (SCBA) with a fully encapsulating protective suit until monitoring results allow for other decisions. Level A protection should be consistent with the description in HAZWOPER Appendix B and suits should be appropriate for CBRN agents. e.g. meets the requirements of NFPA 1994-2001, has been tested by a third party such as the U.S. Army and Soldier and Biological Chemical Command (SBCCOM), or has undergone other manufacturer testing. A NIOSH-certified CBRN SCBA respirator should be used, if available.
Other prudent work practices should include minimizing exposure time to that essential for lifesaving or initial monitoring, avoiding any unnecessary contact with surfaces or potentially contaminated material, use of natural ventilation flows to reduce exposure, mandatory decontamination and post exit evaluation for signs and symptoms of exposure.
Areas where contamination with chemical, biological, radiological, or nuclear (CBRN) agents is possible but active release has ended and initial monitoring exists.
Areas in close proximity to the release area or that are known to be contaminated and certain job activities on the periphery of the event area should be considered for this zone. Risk factors that should be considered include determining the relative risk for job activities from inhalation based on available air monitoring results, skin contact and absorption potential, proximity to the event, and wind directions. Refer to the specific hazard information pages below to select personal protective equipment and limited work durations to reduce exposure to safe levels. Use the other prudent work practices listed above for red zone exposures.
Areas where contamination with chemical, biological, radiological, or nuclear (CBRN) agents is unlikely. This zone covers the area beyond the expected significant dispersal range of the initial event and secondary contamination range caused by traffic and emergency responders.
Even in areas which are not thought to pose a hazard, there may be a concern or potential for a minimal level of transient or unknown exposures in the aftermath of an event. The following suggestions for prudent work practices may reduce the amount of concern regarding this potential:
This product is not a standard or regulation, and it has no effect on employers' legal obligations. The guidance is advisory in nature, informational in content, and is intended only as technical assistance to employers in providing a safe and healthful workplace during emergency response operations. This document does not enhance or diminish any existing obligations under the OSH Act. The information in this document is interim guidance only. It is anticipated that NIOSH CBRN approval for all classes of respirators will be available in the near future. This guidance will change at the time NIOSH CBRN certification standards are available for all respirator classes. OSHA also may update this guidance as additional information becomes available in the future.
*Accessibility Assistance: Contact OSHA's Directorate of Technical Support and Emergency Management at (202) 693-2300 for assistance accessing PDF materials.
All other documents, that are not PDF materials or formatted for the web, are available as Microsoft Office® formats and videos and are noted accordingly. If additional assistance is needed with reading, reviewing or accessing these documents or any figures and illustrations, please also contact OSHA's Directorate of Technical Support and Emergency Management at (202) 693-2300.
**eBooks - EPUB is the most common format for e-Books. If you use a Sony Reader, a Nook, or an iPad you can download the EPUB file format. If you use a Kindle, you can download the MOBI file format.Back to Top
The Department of Labor does not endorse, takes no responsibility for, and exercises no control over the linked organization or its views, or contents, nor does it vouch for the accuracy or accessibility of the information contained on the destination server. The Department of Labor also cannot authorize the use of copyrighted materials contained in linked Web sites. Users must request such authorization from the sponsor of the linked Web site. Thank you for visiting our site. Please click the button below to continue.