California Registered Environmental Health Specialist (REHS) Disaster Management Practice Test 2026 - Free REHS Exam Practice Questions and Study Guide

In hazardous materials operations, zones are arranged so clean areas stay uncontaminated. The clean area is the cold zone, located outside the contamination boundary. It hosts incident command, staging, and support activities, and it's where personnel are no longer exposed to the hazard after decontamination has been completed in the intermediate area. The hot zone contains the hazardous material and requires full protective gear, while the warm zone serves as the transition and decontamination area between hot and cold. Because the cold zone remains free of contamination, it’s the best label for the clean area.