Risk levels of asbestos work

Canadian asbestos regulations do not treat all asbestos work the same. They sort tasks into risk levels according to how many fibres the work is likely to release, and they set precautions, respirators and training to match. Ontario calls these Type 1, Type 2 and Type 3 operations; British Columbia and several other provinces use low-, moderate- and high-risk work; Quebec uses low, moderate and high-risk construction work. The names differ, but the logic is the same. This lesson uses Ontario's scheme as the main example, compares it with the low, moderate and high-risk approach, and explains how to classify a task.

Type 1 operations

Type 1 operations are low-risk tasks that release few fibres when done properly. Ontario's regulation lists them, and they include installing or removing non-friable asbestos-containing material without breaking, cutting, drilling, abrading, grinding, sanding or vibrating it; installing or removing ceiling tiles containing asbestos covering less than 7.5 square metres without breaking or cutting them; breaking, cutting, drilling or similar work on non-friable material using non-powered hand tools while wetting the material, where workers wear protective equipment; and removing less than one square metre of drywall with asbestos-containing joint compound. Precautions include wetting where practicable, using non-powered hand tools, keeping the work area clear, cleaning up dust and waste with a HEPA vacuum or damp methods, and providing a half-facepiece respirator with N-100, R-100 or P-100 filters if the worker requests one.

Type 2 operations

Type 2 operations are moderate-risk tasks. They include removing all or part of a false ceiling to gain access to a work area where asbestos-containing material is likely to be present; removing or disturbing one square metre or less of friable material; enclosing friable material; applying tape, sealant or other covering to pipe or boiler insulation; removing ceiling tiles of 7.5 square metres or more without breaking or cutting them; breaking, cutting, drilling or similar work on non-friable material with non-powered hand tools without wetting; removing one square metre or more of drywall with asbestos joint compound; using power tools fitted with dust collectors and HEPA filters on non-friable material; glove bag removal of insulation; and cleaning or removing filters in air handling equipment in buildings with sprayed fireproofing containing asbestos. Precautions include restricting the work area with signs, wetting friable material, using drop sheets and HEPA vacuums, sealing waste in containers, decontaminating clothing and washing hands and face, and wearing the respirator Table 2 specifies, at least a half-facepiece with a 100-series filter and a full-facepiece or powered respirator for false ceiling work.

Type 3 operations

Type 3 operations are high-risk tasks. They include removing or disturbing more than one square metre of friable asbestos-containing material; spraying sealant onto friable material; cleaning or removing air handling equipment, other than filters, in buildings with sprayed fireproofing containing asbestos; repairing, altering or demolishing kilns, metallurgical furnaces or similar structures made partly of refractory materials containing asbestos; breaking, cutting, drilling or similar work on non-friable material with power tools that are not fitted with dust collectors and HEPA filters; and repairing, altering or demolishing buildings that were used to manufacture asbestos products, unless the asbestos was cleaned up. Type 3 work requires notice to the Ministry, a separated work area, usually a full enclosure under negative pressure maintained at 0.02 inches of water with HEPA-filtered exhaust when indoors, a three-room decontamination facility, wetting, supplied-air or powered respirators as Table 2 requires, daily air monitoring outside the enclosure in some situations, clearance air testing before the enclosure is removed, and workers and supervisors certified as 253W and 253S.

Low, moderate and high-risk work in other provinces

BC, Alberta, Quebec and several other jurisdictions classify work as low, moderate or high risk rather than by type. WorkSafeBC guidance, for example, describes low-risk work as work with non-friable material that releases few fibres using hand tools and wetting; moderate-risk work as work that can release more fibres, such as removing non-friable material with methods that break it, or small amounts of friable material using local containment; and high-risk work as removal of friable material or work that releases large amounts of fibres, requiring full enclosures, negative air and decontamination. Classification in these provinces is often part of the exposure control plan and is made by a qualified person. The boundaries and specific precautions differ, so check your province's regulation and guidelines.

Why the type depends on method as well as material

The same material can fall into different types depending on how it is handled. Cutting asbestos-cement board with a non-powered hand tool while wetting it is Type 1; cutting it with hand tools without wetting is Type 2; cutting it with a power saw without a HEPA dust collector is Type 3. The regulation rewards low-fibre methods with lighter precautions. This gives supervisors a powerful planning tool: choosing a better method can reduce the risk level, the precautions and the cost.

Classifying a task

Classification is the job of a competent person who knows the regulation, the material and the method. A simple decision function shows the logic, but real classification must follow the full regulation, including the special cases this sketch leaves out.

# Simplified sketch of Ontario-style classification (not a substitute for O. Reg. 278/05)
def ontario_type(friable, area_m2=0.0, method="hand", wetted=True, hepa_collector=False):
    if friable:
        return "Type 3" if area_m2 > 1.0 else "Type 2"
    # non-friable material
    if method == "intact":
        return "Type 1"
    if method == "hand":
        return "Type 1" if wetted else "Type 2"
    if method == "power":
        return "Type 2" if hepa_collector else "Type 3"
    return "assess"

tasks = [
    ("remove floor tiles intact",            dict(friable=False, method="intact")),
    ("wet hand-cut cement board",            dict(friable=False, method="hand", wetted=True)),
    ("dry hand-cut cement board",            dict(friable=False, method="hand", wetted=False)),
    ("drill cement board, HEPA shroud",      dict(friable=False, method="power", hepa_collector=True)),
    ("drill cement board, no collector",     dict(friable=False, method="power", hepa_collector=False)),
    ("repair 0.5 m2 of pipe lagging",        dict(friable=True, area_m2=0.5)),
    ("strip 12 m2 of sprayed fireproofing",  dict(friable=True, area_m2=12)),
]
for name, kw in tasks:
    print(f"{name:38s} {ontario_type(**kw)}")

remove floor tiles intact              Type 1
wet hand-cut cement board              Type 1
dry hand-cut cement board              Type 2
drill cement board, HEPA shroud        Type 2
drill cement board, no collector       Type 3
repair 0.5 m2 of pipe lagging          Type 2
strip 12 m2 of sprayed fireproofing    Type 3

The output shows how the method changes the type for the same cement board. A supervisor planning to drill a few holes through cement board can keep the work at Type 2 by using a drill with a shroud connected to a HEPA dust collector, or at Type 1 by using wetted hand tools where practicable, instead of creating a Type 3 operation with an uncontrolled power drill.

The role of the competent person and supervisor

Whatever the scheme, someone must make the call before work starts. In Ontario, the employer must classify the operation, and supervisors of Type 3 work must hold 253S certification. In BC, a qualified person classifies work in the exposure control plan. A supervisor who is not qualified to classify should know enough to recognize that classification is needed and to stop work until it is done. Reclassification is needed whenever the method, material or quantity changes, for example when a planned intact removal starts breaking the material.

Common classification questions

Do the areas of separate small jobs add up? Ontario's regulation classifies work in the same room or enclosed area by the total area, so several small patches of friable material in one room can together exceed one square metre and make the work Type 3. Splitting a job into small pieces to stay under a threshold is not acceptable.

What if the material is assumed rather than tested? Assumed material is treated as asbestos-containing, and the work is classified as if the material were friable or non-friable according to its nature. Testing first can sometimes show that no precautions are needed.

Who decides when the answer is unclear? The employer, advised by a competent person or consultant. When in doubt, choose the higher risk level until the question is resolved.

Working with consultants and specifications

On larger projects, an asbestos consultant usually prepares specifications that set out the classification of each task, the enclosure design, the respirators, the monitoring and clearance criteria and the waste arrangements. Specifications often go further than the regulation, for example requiring higher air change rates, full enclosures for some Type 2 work or more frequent air sampling. The contractor must meet both the regulation and the specification. Supervisors should read the specification before work starts, raise any conflict with the regulation, and never assume that the minimum legal requirement is all that the contract demands.

Specifications also define who has authority to stop the work and what happens when results exceed a trigger. Knowing these rules before the job starts avoids arguments in the middle of an abatement.