Asbestos killed more Ontario workers in the last decade than any other occupational disease. The fibres are microscopic, the exposure is often invisible, and the diseases it causes — mesothelioma, asbestosis, and lung cancer — can take 20 to 40 years to manifest. By the time a worker is diagnosed, the damage is irreversible. For construction workers in Ontario, particularly those involved in renovation, demolition, or maintenance of buildings constructed before 1980, asbestos exposure is not a historical problem. It is a daily risk.
Ontario Regulation 278/05 under the Occupational Health and Safety Act specifically addresses asbestos on construction projects and in buildings and repair operations. Every worker, supervisor, and employer on a project that may involve asbestos-containing materials (ACMs) needs to understand this regulation.
Where Asbestos Is Found in Pre-1980s Buildings
Asbestos was used extensively in Canadian construction from the 1930s through the late 1970s because of its remarkable resistance to heat, fire, and chemical damage. If you are working on any building constructed or renovated before 1990, you should assume asbestos is present until proven otherwise. Common locations include:
Pipe and boiler insulation — wrapped around heating pipes, ductwork, and boilers. This is often the most friable (easily crumbled) form and poses the greatest risk when disturbed.
Spray-applied fireproofing — applied to steel beams, columns, and ceiling decks for fire protection. Commonly found in commercial and industrial buildings.
Floor tiles and mastic — 9x9-inch vinyl floor tiles manufactured before 1980 frequently contain asbestos, as does the black adhesive (mastic) used to bond them to the subfloor.
Cement products — asbestos cement (transite) was used for siding, roofing shingles, soffits, water pipes, and flue pipes. These materials are non-friable when intact but become hazardous when cut, drilled, or broken.
Drywall joint compound — some joint compounds manufactured before 1980 contained chrysotile asbestos. Sanding these compounds releases fibres directly into the worker's breathing zone.
Ceiling tiles and plaster — textured ceilings (popcorn ceilings), acoustic ceiling tiles, and some plaster formulations contained asbestos.
Electrical components — wiring insulation, electrical panel backing boards, and arc chutes in older electrical panels may contain asbestos.
The Owner's Duty to Disclose
Under O. Reg. 278/05, the owner of a building has a legal obligation to determine whether asbestos-containing materials are present before any construction work begins. This typically involves hiring a qualified person to conduct a designated substance survey. The owner must provide the results of this survey — including the locations, types, and condition of any ACMs — to the constructor and employer before work starts.
If you are a constructor or employer and the owner has not provided an asbestos survey, you must request one. Do not proceed with demolition or renovation work in a pre-1980s building without this information. The liability falls on every party in the chain — owner, constructor, employer, and supervisor.
Type 1, Type 2, and Type 3 Operations
O. Reg. 278/05 classifies asbestos work into three categories based on the level of risk. Each type has specific requirements for procedures, engineering controls, and worker protection.
Type 1 operations — the lowest risk category. This includes installing or removing non-friable asbestos-containing materials where the material will not be broken, cut, drilled, abraded, or otherwise disturbed in a way that could release fibres. Examples include removing intact cement board or floor tiles using methods that keep the material whole. Workers must be trained, and the employer must provide a respirator to any worker who asks for one, but full enclosure is not required.
Type 2 operations — moderate risk. This includes work that may disturb friable or non-friable ACMs, such as removing one square metre or more of drywall with asbestos-containing joint compound, cutting asbestos cement pipe with hand tools without wetting it (or with power tools fitted with HEPA dust collectors), removing pipe insulation with a glove bag, or removing or disturbing one square metre or less of friable ACM such as damaged insulation. Type 2 operations require warning signs, respirators and protective clothing for everyone in the work area, wet methods, drop sheets and HEPA vacuums for clean-up; some indoor work on friable material must be enclosed where practicable, and glove-bag removals have their own rules.
Type 3 operations — the highest risk category. This includes removing or disturbing more than one square metre of friable ACM (such as insulation or spray-applied fireproofing), spray-applying sealant to friable ACM, and cutting or grinding non-friable ACM with power tools that have no HEPA dust collector. Indoors, Type 3 operations require a full enclosure kept under negative air pressure by a HEPA-filtered exhaust unit, decontamination facilities (clean room, shower, dirty room), full protective clothing, the respirator the regulation specifies for the material and method (supplied-air for dry removal), and a clearance air test before the enclosure comes down. Only workers with specific Type 3 asbestos training may perform this work.
Worker Training Requirements
Every worker in a Type 1, Type 2 or Type 3 operation must receive instruction and training from a competent person in the hazards of asbestos, personal hygiene and work practices, and the use, cleaning and disposal of respirators and protective clothing. The level of training required depends on the type of operation.
Awareness training — all workers on sites where ACMs are present must understand the health hazards of asbestos, how to recognize ACMs, and what to do if they suspect they have encountered asbestos. This is good baseline practice; what the regulation requires is that the constructor or employer tell every worker whose work involves ACMs, or could disturb them, where those materials are and whether they are friable.
Type 1 and Type 2 training — workers performing Type 1 or Type 2 operations must receive additional training specific to the procedures, controls, and PPE requirements for their work type.
Type 3 training — workers performing Type 3 operations must complete comprehensive training that covers full enclosure construction, negative air systems, decontamination procedures, air monitoring, and emergency response. This training is typically delivered over several days by specialized providers.
Air Monitoring
Air monitoring during Type 2 and Type 3 asbestos operations is good practice to verify that control measures are effective and that fibre concentrations stay low, but O. Reg. 278/05 makes only one air test mandatory: the clearance air test at the end of an indoor Type 3 operation. Ontario's OEL for chrysotile asbestos is 0.1 fibres per cubic centimetre of air, averaged over an 8-hour time-weighted average. The same limit applies to every form of asbestos, including amosite and crocidolite.
Personal air monitoring — sampling pumps worn by workers measure the concentration of airborne fibres in the worker's breathing zone during the operation.
Area monitoring — stationary samplers placed at the perimeter of the work area and at the boundary of the enclosure verify that fibres are not escaping into adjacent spaces.
Clearance testing — after abatement is complete and before the enclosure is dismantled, clearance air samples must confirm that fibre levels have returned to acceptable levels.
Medical Surveillance
Employers must complete an asbestos work report at least once a year for every worker in a Type 2 or Type 3 operation and send it to the Ministry's Provincial Physician, who keeps an Asbestos Workers Register. On the Provincial Physician's recommendation, a registered worker can volunteer for a medical examination (a medical questionnaire, chest X-rays and pulmonary function tests), and the employer pays for it. A follow-up examination can be done if the worker's physician recommends it, at least five years after the most recent one.
Medical surveillance does not prevent disease, but it allows for early detection of asbestos-related changes in the lungs, which can inform treatment decisions and support future WSIB claims.
Removal and Disposal
Asbestos-containing materials removed from a building must be wetted, double-bagged in sealed 6-mil polyethylene bags labelled with the asbestos warning symbol, and transported to a waste disposal site approved to accept asbestos waste. The bags must not be dropped, thrown, or compacted in a way that could rupture them. Waste manifests must be maintained documenting the quantity, source, and destination of all asbestos waste.
Asbestos is not a problem you can manage by ignoring it. It is a problem you manage by knowing where it is, understanding the regulations, training your workers, and following the procedures exactly as prescribed. The consequences of getting it wrong do not show up on the day of the exposure. They show up 20 years later in a hospital room. That is what makes asbestos the most insidious hazard on any construction site.
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