What type of signs are to be placed on all routes leading into contaminated areas?

In CBRN (Chemical, Biological, Radiological, and Nuclear) reconnaissance operations, it is crucial to communicate the presence of potential hazards effectively to ensure safety. Radiological warning signs are specifically designed to alert personnel and the public about the existence of radiological contamination or danger in the area. These signs provide vital information about the nature of the threat, indicating that the area poses a risk from radiation exposure.

Radiological warning signs are essential because they help prevent accidental entry into contaminated zones, which can lead to exposure and health risks. By placing these signs at all routes leading into contaminated areas, authorities can facilitate informed decision-making and promote safety protocols, such as personal protective equipment requirements and decontamination procedures.

The other types of signs listed may serve important functions in different contexts, such as indicating the presence of hazardous materials, directing evacuation efforts, or indicating fire hazards. However, they are not specific to the warning of radiological threats, which is the focus of this question. Thus, the placement of radiological warning signs is paramount in ensuring that personnel are adequately informed and can take the necessary precautions when approaching an area known to be contaminated with radiological materials.