Should clearance testing in Calgary be done by a separate company?

Clearance testing does not have to be done by a separate company under Alberta OHS rules, but we recommend an independent consultant, for the reasons below.

The Alberta Asbestos Abatement Manual describes keeping a high-risk enclosure under negative pressure until air results confirm fibre levels are low enough to dismantle it, and it describes final results below 0.01 fibres per cubic centimetre for moderate-risk work; for low-risk work that figure is a level to stay under during the work. Neither the Code nor the Manual names who must collect those samples. The Manual, as guidance rather than law, describes aggressive sampling and final air testing as part of a proper closeout, but it does not require an independent party.

So why does independence matter in practice? When the same crew that did the abatement also collects the clearance samples, there is no outside check on whether the area was properly cleaned before sampling began, whether the right number of samples were taken, or whether the lab received them correctly. An independent industrial hygienist or environmental consultant has no financial interest in a passing result. Their written clearance letter is also what the City of Calgary's demolition permit guide asks for: a clearance letter stating that all asbestos materials have been properly removed and the area is acceptable for demolition, submitted to the authority having jurisdiction at the time of inspection.

A few things worth asking any contractor before the job closes:

• Who collects the clearance air samples, and are they employed by the abatement company or independent of it?
• Which lab analyzes the samples, and does it participate in a proficiency testing program? The Manual says it should.
• Will the clearance letter name the sampling method (PCM counts fibres but cannot identify asbestos; TEM positively identifies it) and the result against the 0.01 fibres per cubic centimetre threshold?
• If a containment was used, will aggressive sampling be done before the enclosure comes down?

For a demolition project in Calgary, the City also expects a copy of the asbestos assessment showing sample numbers and locations, alongside the clearance letter, at the time of inspection. The 72-hour OHS notification filed through Alberta's asbestos portal before work began is a separate document, and the abatement contractor is responsible for filing it.

After the job is finished, keep the full lab report with sample locations and results, a copy of the OHS 72-hour notification confirmation, the signed clearance letter from whoever did the air testing, and the Shepard landfill receipt showing the waste was disposed of properly.

When contractors reply through the form on this page, ask each of them the four questions above.