What result means a Calgary room is cleared after asbestos removal?

After asbestos abatement, the Alberta Asbestos Abatement Manual describes the clearance standard by risk class. For low-risk work, air monitoring should stay below 0.01 fibres per cubic centimetre during all phases of the work. For moderate-risk work, final air results must be less than 0.01 fibres per cubic centimetre, with aggressive sampling required if a containment was used. For high-risk work, the enclosure stays under negative pressure until air tests confirm fibre levels are low enough to dismantle the containment safely.

What the numbers mean in practice

The Alberta OHS Code's occupational exposure limit for asbestos is 0.1 fibres per cubic centimetre; the 0.01 figure above is the Manual's final clearance level for moderate-risk work. Clearance sampling is the measured check that fibre levels came down before drywall, flooring or insulation goes back in.

The lab method matters too. PCM (NIOSH 7400) counts all fibres in an air sample but cannot distinguish asbestos from other mineral fibres, and TEM (NIOSH 7402) positively identifies asbestos fibres; ask which one your consultant's lab will use. The Manual says labs should participate in a proficiency testing program; Alberta law does not require lab accreditation, so it is worth asking the consultant which lab they use and whether it participates in such a program.

One practical point: clearance sampling done by the same crew that performed the abatement is a conflict of interest. Ask for a consultant who is independent of the abatement contractor, and confirm that consultant will be the one submitting samples to the lab and interpreting the results. Published Calgary-area prices read in September 2026 put air clearance testing at roughly $200 to $700 per area, depending on the number of samples and whether a written report is included.

For a Calgary renovation or demolition, the City's Asbestos Abatement Information Form requires a declaration that all materials with the potential to release fibres have been removed from the project area and disposed of properly before a building or demolition permit is released. If the abatement happens after a permit issues because material was found mid-project, the City requires that work stop immediately, that the Alberta OHS 72-hour notification be filed, and that a building permit revision be submitted. The clearance letter confirming the area is acceptable for demolition must be provided to the authority having jurisdiction at the time of inspection.

Contractors who reply through the form on this page should be able to answer all four of those questions.

Before you accept any quote, ask the contractor to spell out in writing exactly what the clearance line item covers: who collects the samples, which lab analyzes them, which method is used, and whether the written clearance report is included in the price or billed separately.