Three-part metering series for hazmat responders that explains what common meters actually measure, why readings matter, and how to turn instrument data into tactical decisions on scene. Part 1 covers goals and zone setup, Part 2 explains meter mechanics, sampling methods, response time, calibration and common interferences, and Part 3 shows how to map concentrations, find and control sources, and choose ventilation versus isolation to protect victims and crews. Watch all three in order to build a simple, practical framework for metering driven decision making.