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FAQs on Asbestos – St. George Campus

Frequently Asked Questions (FAQs) on Asbestos – St. George Campus

I would like to have clearance air testing/forced air testing performed in my lab (New FAQ April 5, 2017):

Our top priority is to provide a place that is safe for our faculty staff and students. To do that we’ve brought in experts to do regular tests of the air at the Medical Sciences Building because we know that asbestos is harmful when it is airborne. Those experts are using best practices to do those tests and they have found the building safe. The Ministry of Labour also has visited the site three times and they are satisfied with the steps we are taking.

We’ve been asked by some people why were are not doing other kinds of tests in the building. We are relying on the advice of experts and following industry best-practice.

Clearance air testing is defined in Ontario Regulation 278/05 and takes place under controlled conditions that does not reflect the building occupant’s exposure to asbestos nor the exposure of asbestos workers inside the enclosure. Clearance testing takes place inside Type 3 enclosures after the abatement work is complete and after a thorough cleaning and a visual inspection by a Qualified Person. Forced air (a leaf blower) is then used to dislodge any remaining fibres in the enclosure. Clearance testing results are a measure of the effectiveness of Type 3 procedures and do not reflect occupational exposures. The clearance standard in Regulation 278/05 is 0.01 fibres/cubic centimetre (cc) (f/cc). The MOL has confirmed in their MOL field visit reports that the requirements of 278/05, which includes the clearance limit, does not apply for ambient air sampling at MSB. It would only apply under the specific conditions set out above.

In Ontario, the regulated Time Weighted Average (TWA) exposure limit is 0.1 f/cc. Air sampling results are compared to this value.

It is also applicable and common health and safety practice to use an “action level” which is 50% of the TWA. This is not a regulated limit but an internal organizational practice which may be employed out of an abundance of caution. When airborne fibres are at 50% of the TWA, additional review takes place to validate the result. For asbestos, this often involves a second analytical method (Transmission Electron Microscopy Testing or TEM) which has the ability to distinguish asbestos from other fibres.

Ambient air sampling is conducted to evaluate potential exposure to asbestos. Therefore results are compared to the TWA exposure limit and the University’s action limit, which is 50% of the TWA exposure limit.

Ambient air samples are collected during typical work and environmental conditions in the building.

The MOL does not prescribe a specific method for adjusting the OEL (Occupational Exposure Limit) to account for shifts >8 hours but in practice, a reduction is applied using various models. The most common model is to reduce the OEL proportionally. For a 12 hour work day (50% longer), reduce the OEL by 50% which brings us to the action limit we already use. Where airborne fibres appear to be higher than 50% of the OEL, a second analysis by (TEM) is performed. TEM has the ability to distinguish asbestos fibres. Where TEM analysis has been performed, results were well below the occupational exposure limit. In fact, no asbestos fibres were detected in most of the samples analysed by TEM. Therefore; all air sampling results to date have been below 50% of the OEL for asbestos.

If you work or learn at MSB (New FAQs: March 30, 2017):