What does 0.01 fibres per cubic centimetre mean for my Ottawa job?

The 0.01 fibres per cubic centimetre figure is the clearance threshold set by O. Reg. 278/05, section 18, for the PCM air-sampling method. Every air sample collected inside the enclosure after Type 3 asbestos work must come in at or below that concentration for the area to pass. If any single sample exceeds it, the area does not pass.

What this means for your job

Clearance air testing under section 18 applies only after Type 3 work, which is the removal or disturbance of more than one square metre of friable asbestos-containing material, or certain power-tool operations. Whether your job is Type 3 depends on whether the material is friable and how much of it is disturbed. The contractor assesses that on site. You can ask for the Type in writing before work starts.

The test is conducted by a competent worker once the enclosure is dry. At least 2,400 litres of air are drawn per filter. Results must be posted within 24 hours. As the owner, you keep a copy of those results for at least one year. That one-year copy is not optional: it is what section 18 requires.

The alternative sampling method is TEM. Under section 18, the TEM method passes if the inside average is statistically less than the outside average, or if there is no statistical difference between them. The regulation does not rank one method above the other.

A few things worth knowing about scope:

• Clearance air testing appears only in the Type 3 section of O. Reg. 278/05. The Type 1 and Type 2 sections do not require it.
• You can ask any contractor to include a clearance test in their quote for Type 1 or Type 2 work, even though it is not required by law for those Types.
• The clearance test exception in section 18 covers a building that is to be demolished and will not be entered by anyone except the workers doing the demolition.
• Published prices for an air clearance test in Ontario run roughly $300 to $800, based on published contractor prices read in September 2026.

Before Type 3 work begins, the employer or constructor must also notify, orally and in writing, an inspector at the nearest Ministry of Labour office. That notice is given before the work commences; the regulation sets no number of days in advance.

After the job is done, the documents worth keeping together are the original lab report confirming the material contained asbestos, the written Type the contractor assessed for the work, and the clearance air test results, which section 18 requires you to hold for at least one year.