Clearance Air Testing

Clearance air testing is the final air sampling done inside a work area after asbestos abatement, before the containment is taken down and people are allowed back in. The air is stirred up on purpose and sampled; if fiber levels are too high, the area must be cleaned again and retested.

Origin

Clearance testing developed with large-scale asbestos removal in schools and public buildings in the 1980s. The EPA's AHERA regulations for schools, issued in 1987, set formal clearance requirements, generally using electron microscopy for larger projects, and many states and building owners apply similar rules elsewhere.

Significance in Asbestos Context

Clearance testing is the main check that an abatement job actually left a space safe to reoccupy. Under AHERA it is done with "aggressive" sampling, using leaf blowers and fans to lift settled dust into the air so the test reflects what people might later disturb. Larger school projects generally require analysis by transmission electron microscopy against a set structure limit, while small projects may use phase contrast microscopy. For families and building occupants, a failed or skipped clearance test, or one done without aggressive methods, can be evidence that a building stayed contaminated after supposed removal. Requirements outside schools vary by state and by contract, so what was required depends on the building and the date.

Example Sentence

The school district's records showed the classroom passed TEM clearance air testing only on the third try, after two more rounds of cleaning.

Related Terms

Abatement, AHERA, AHERA TEM Method, Air Sampling, Transmission Electron Microscopy (TEM), Phase Contrast Microscopy (PCM), Wipe Sampling, Asbestos Management Plan

Notes

• If asbestos was removed from your home, school or workplace, ask the owner or contractor for the clearance test report.
• Schools must keep AHERA records, including abatement and clearance documents, available for review.
• A passed clearance test shows conditions at the end of the job; it does not show what workers or occupants breathed during it.