Routine environmental monitoring ensures a safe compounding environment and is used to test for viable and nonviable particle levels. Environmental monitoring includes testing the temperature, pressure differential, nonviable particles, surface sampling, and viable electronic device sampling at least every six months. It also involves monitoring humidity, sound, and lighting levels. Environmental sampling should occur throughout the entire compounding area including the ISO Class 5 PEC, buffer areas, ante-areas, and segregated compounding areas.