After the work area passes the visual inspection, air samples are collected by a state-licensed Air Monitoring Specialist (AMS). Air sampling cassettes are attached to an electric-powered vacuum pump usually operating at a flow rate of around 10 liters per minute. Air flows through an open-face, 25-mm diameter filter. The air sampling typically takes about an hour and a half.
The filters from the cassettes are typically analyzed on-site by the AMS. The analyst uses the phase contrast microscopy in accordance with the National Institute of Occupational Safety and Health Method 7400.
The Aggressive air sampling method is used in this process after the final visual inspection has passed. The AMS will use a leaf blower to aggressively stir up any remaining particles with in the containment in order to collect adequate samples from within the work area. After the samples have been collected and the PCM analysis meets criteria, the abatement contractor can proceed to tear down containment
