To prevent the spread of contamination and minimize the number of additional casualties resulting from either the initial release or lingering hazards, site access for emergency response personnel may need to be limited, and the site and surrounding areas may need to be isolated from the public and the media.
Site security is necessary to:
- Prevent the exposure of unauthorized, unprotected people to site hazards
- Prevent theft or vandalism
- Avoid interference with safe working procedures
- Protect a potential crime scene including evidence of criminal activity
When defining areas for site access control, responders should realize that both the accident site and downwind/downslope regions may remain hazardous for some time (note that downwind and downslope regions may be in different directions). Unprotected individuals, such as crowds drawn to an accident site, should be prevented from entering these regions.
Law enforcement personnel are essential for quickly establishing and controlling a perimeter to limit entry to a potentially contaminated area and for shutting down highways that may be in the path of a large toxic plume. Travel and site access limitations must be communicated to the public, especially if road closures must occur at the same time an evacuation has been ordered.