A system for sampling air in a controlled environment that includes two or more air sampling devices at different locations within the controlled environment. A controller is provided at a location outside of the controlled environment and in separate air flow communication with each air sampling devices via separate first vacuum tubes. A ffow switch for each of the air sampling devices is provided at a location between a corresponding air sampling device and the vacuum source, each of the flow switches being configured to separately measure and control the rate of air flow through a corresponding first vacuum tube. An alarm is automatically activated at a location inside the controlled environment by one or more of the flow switches when the rate of air flow measured at one or more of the flow switches deviates from a desired value by a predetermined amount.