What is a clearance air test after asbestos removal in Ontario?

A clearance air test is the air test O. Reg. 278/05 requires inside the enclosure after Type 3 asbestos removal, once the enclosure is dry. Published Ontario contractor prices read in September 2026 put it at about $300 to $800.

What the regulation requires

Section 18 of O. Reg. 278/05 is the only place clearance air testing appears. Once the enclosure is dry after Type 3 work, a competent worker collects air samples inside it. There are two accepted methods. Under the PCM method, every sample must show a fibre concentration no greater than 0.01 fibres per cubic centimetre of air, and at least 2,400 litres of air must be drawn through each filter. Under the TEM method, the area passes if the inside average is statistically less than the outside average, or if there is no statistical difference between the two. Results must be posted within 24 hours of the test, and the owner keeps a copy for at least one year.

One exception applies: a building that is going to be demolished and will not be entered by anyone except the workers doing the demolition does not require a clearance test.

It is worth knowing what the regulation does not say. Sections 14 through 17, which cover Type 1 and Type 2 work, contain no clearance air test requirement. If your job is classified as Type 1 or Type 2, the law does not require a clearance test, though you can ask for one to be included in the quote.

A clearance test is not the same as the pre-removal bulk sample test that identifies whether material contains asbestos. The clearance test measures airborne fibres after the work is done, not the material itself.

A few things to confirm before the test happens. Ask the contractor to tell you in writing which Type the job falls under, because that determines whether a clearance test is legally required or optional. For Type 3 work, O. Reg. 278/05 section 20 requires every worker to have completed the Asbestos Abatement Worker Training Program and every supervisor the Asbestos Abatement Supervisor Training Program before work begins. Section 11 requires the constructor or employer to notify, orally and in writing, an inspector at the nearest Ministry of Labour office before a Type 3 operation starts. You can search a contractor's current WSIB clearance online.

What a fair quote for Type 3 work should include: the job Type in writing, confirmation of the Ministry of Labour notice, the clearance air test with the method specified, and the name of the disposal site that has agreed to accept the asbestos waste under Ontario Regulation 347.

If you are unsure whether your job reaches the Type 3 threshold, ask the Ministry of Labour, whose inspectors receive the Type 3 notice.