A sampling system for quantifying the amount of contaminants in a controlled environment within a facility. The system has an air sampling devices each associated with a respective flow switch module, both within the controlled environment, and a first and second controller located outside the controlled environment. The first controller is in flow communication with the air sampling devices. The first controller is also in flow communication with the flow switch modules and controls a vacuum source to draw a predetermined volume of air through the at least one air sampling device via the at least one flow switch module at a desired flow rate. The flow switch module detects when the actual flow rate falls below or above a predetermined value, and generates an alarm.