Post-Abatement Clearance & Air Testing

Clearance is the proof that the job is finished. For asbestos, the Alberta Asbestos Abatement Manual expects moderate-risk work to end with final air results under 0.01 fibres per cubic centimetre, using aggressive sampling if a containment was built, and high-risk enclosures to stay under negative pressure until air tests confirm fibre levels are low enough to take the enclosure down.

The Manual describes phase contrast microscopy as the standard air count, which cannot tell asbestos from other fibres, and transmission electron microscopy as the method that positively identifies asbestos when that matters.

For a demolition in Calgary, the clearance letter is not optional. The City's demolition permit guide requires the asbestos assessment and a clearance letter stating that all asbestos materials have been properly removed and the area is acceptable for demolition, handed to the inspector at the time of inspection.

The point worth insisting on is independence. Clearance sampling done by the same company that did the abatement is a self-graded exam. Ask for a third-party consultant to take the samples, and ask which lab counts them and whether that lab takes part in a proficiency program, which the Manual recommends though Alberta law does not require it.

For mould there is no legal clearance standard in Alberta. A post-remediation check is a visual and moisture inspection, sometimes with surface or air samples for a documented baseline. Keep in mind Health Canada's position that air results cannot be used to assess health risk. Published Calgary-area and Canadian prices for asbestos air clearance run roughly $200 to $700 per area, depending on how many samples and whether a written report is included.