Air sampling professional
analyzing clearance air testing slide

Final Inspection and Clearance Testing

After asbestos removal work in a particular area is completed, a final inspection and clearance air testing is performed to confirm that the work area is safe for re-occupancy.  According to state regulations, clearance testing cannot be conducted by the remediation company.  The usual charge is around $400.

The most important part of the clearance process is the final inspection.  The independent environmental technician visually examines the substrate surfaces to ensure that no asbestos-containing material (ACM) remains.  Special attention is given to horizontal and irregular surfaces and hard-to-reach areas.  If any quantity of ACM remains, the site fails the visual inspection, and additional removal and/or cleaning needs to be performed before another visual inspection is conducted.

After the work area passes the visual inspection, air samples are collected by a state-licensed air sampling professional (ASP).  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 ASP.  The analyst uses the phase contrast microscopy in accordance with the National Institute of Occupational Safety and Health Method 7400.

Most residential asbestos removal projects are priced assuming that clearance sample analysis will be done on-site, directly following the completion of the project as described above.  If off-site analysis or transmission electron microscopy TEM testing is performed, the price of the asbestos removal project will be increased since the abatement company will have to return to the site to dismantle the containment and retrieve equipment sample analysis is completed.