Foundations of Construction: Asbestos—tremendously versatile, sadly dangerous

Subscribe to the OCN Daily Newsletter!

Receive a free update of the latest Ontario Construction News each morning -- Cancel anytime!

Susanna McLeod

Special to Ontario Construction News

The silicate mineral was considered an endlessly useful product. Asbestos could withstand high heat, wear, fire, and chemicals. Its tensile strength in automotive products and construction materials was nearly unmatched. But there was a catch. In the form of tiny airborne particles, asbestos was proven to cause cancer and mesothelioma. Manufacture was prohibited, but asbestos remains in older homes, buildings, and other products.

Naturally-formed, asbestos is geologically categorized into amphiboles and serpentines. Chrysotile is serpentine and the preferred type for industrial purposes. Occasionally called white asbestos, chrysotile features longer, flexible fibres and is found with serpentinite ultramafic deposits.

For thousands of years, asbestos was an all-purpose component used around the globe to strengthen “clay pottery and cloth, including funeral shrouds, napkins, tablecloths, and wicks,” said Ontario Health Clinics for Workers, Inc. (OHCOW).

Mined in Canada in 1870s at Jeffrey Mine in the Thetford Mines region of Quebec, asbestos was also mined in British Columbia, Yukon, Newfoundland, and in smaller quantities in northern Ontario. At one time, Jeffrey Mine was Canada’s largest open-pit mine and a nearby town was proudly named Asbestos, Quebec.

Defined as “incombustible,” the versatile asbestos reached approximately four thousand applications. The mineral also could be processed in many ways. “Techniques of manufacturing asbestos in moulds rather than in woven form have allowed the utilization of short fibres which were previously considered a waste product of the milling process,” said M.A. Vos in the 1971 provincial government report, “Asbestos in Ontario.” Availability of asbestos allowed a range of applications in automobile and aircraft manufacturing, road building, and construction industries.

Mixed into a spray for fireproofing, asbestos was applied to “beams, columns, trusses, joists, and steel pan floors,” according to Infrastructure Health and Safety Association (IHSA). Holding superhero strength as an energy-reducing insulator, asbestos fibres were integrated as the main element of spray insulation for the construction industry.

Creating an array of insulation products, asbestos was mixed in a colloidal suspension and converted into a foam. The material was formed into insulating products such as air-cell paper that was wrapped around steam pipes and boilers. “A compound of 85 weight percent basic magnesium carbonate bonded with 15 percent by weight of asbestos fibre,” the material was used to insulate pipes up to 600°F, Vos stated. Applied as electrical insulation, the asbestos paper was treated with silicone lacquer to prevent moisture absorption.

Acoustic tiles were manufactured with sound-buffering asbestos, and the mineral was used in roofing, decorative panelling, and floor tiles and sheets. It was used in siding, gaskets and in plaster applications. Asbestos was combined with asphalt, as well as made into a slurry with cement for durable sewer pipes. Asbestos held tremendous commercial value.

The negative aspects of the mineral emerged with “records of adverse health effects experienced by asbestos miners and millers (dating) back to the late 1890s and early 1900s.” Nearly eight decades later, the problems suffered by workers—fatigue, coughing up blood, and shortness of breath—were recognized as caused by asbestos.

When a person inhaled the indestructible fibre dust, “it was impossible for the body to break the fibres down and it eventually led to lung scarring and death,” according to CBC News Portal in “Asbestos: The magic mineral that was once Canada’s Gold,” June 10, 2010.

Asbestos dust may remain airborne for several days before it settles and is easily stirred back into the air when disturbed. Larger fibres settle more quickly. Carried long distances on the wind, asbestos particles may also be swept away by water, but the mineral does not dissolve.

By the late 1970s, asbestos use peaked then rapidly declined when health hazards were clearly defined. The Occupational Health and Safety Act of 1985 presented strict regulations on asbestos. “Canada stopped mining asbestos in 2012 and new asbestos use was banned in Canada in 2018,” said OHCOW. However, by this time, asbestos was fully incorporated into the construction industry, insulating homes and buildings built before 1990. Safe asbestos abatement became an industry itself.

Three levels of asbestos products define the health dangers of working with the mineral, from Type 1 (low), Type 2 (medium), to Type 3 (high). Low risk includes asbestos “tightly bound in the original product and in good condition,” said Canadian Centre for Occupational Health and Safety (CCOHS). Asbestos “sealed behind walls and floorboards, isolated in the attic,” and “left undisturbed” present no dire health risks. Asbestos products that are “friable,” easily crumbled or broken by hand present significant health dangers.

Illness and deaths persist from asbestos. The most recent statistics indicate that 410 Canadians were diagnosed with mesothelioma in 2018. In 2020, 522 Canadians died from the disease.

Asbestos handling demands specific procedures and trained professionals on the job site. Visit Ontario.ca for requirements and guidance under Occupational Health and Safety Act, specified in O. Reg.278/05.