An essential element of any hazardous substance release site is the establishment of safety or work zones. These zones are established primarily to reduce the accidental spread of hazardous substances by workers or equipment from contaminated areas to clean areas. Safety zones specify:

• The type of operations that will occur in each zone;
• The degree of hazard at different locations within the release site; and
• The areas at the site that should be avoided by unauthorized or unprotected employees.

The three most frequently identified zones are below:

1. The exclusion zone (or hot zone) is the area with actual or potential contamination and the highest potential for exposure to hazardous substances.
2. The contamination reduction zone (or warm zone) is the transition area between the exclusion and support zones. This area is where responders enter and exit the exclusion zone and where decontamination activities take place.
3. The support zone (or cold zone) is the area of the site that is free from contamination and that may be safely used as a planning and staging area.