What is Asbestos?

Apr 11, 2018

Environmental Enlightenment #108

Some material in this issue has been copied from a “What is Asbestos” July 2003 Fact Sheet by Cal EPA Department of Toxic Substances Control.

Asbestos is a common name for a group of naturally occurring fibrous silicate minerals that are made up of thin but strong durable fibers. These fibers generally vary in size and physical shape.

Because of its physical properties, asbestos was used extensively in construction and many other industries. For example, asbestos would commonly be found in a variety of man-made products including insulation, ceiling and floor tiles, roof shingles, cement, automotive brakes and clutches.

Asbestos containing material that can be crushed into powder using ordinary human hand pressure is termed “friable asbestos.” When asbestos containing materials become friable, there is chance that asbestos fibers can become suspended in air. It is under these conditions that airborne asbestos fibers represent the most significant risk to human health.

Asbestos is a potential health concern because long term, chronic inhalation exposure to high levels of asbestos can cause lung diseases such as asbestosis, mesothelioma, and/or lung cancer.

Asbestosis is a scarring of the lungs due to lodging of asbestos particles in the small air pathways of the lungs. Blood flow to the lungs may also be decreased and this may cause enlargement of the heart.

It is important to note that information on health effects related to asbestos exposure most commonly come from studies of people who have had long term exposures to relatively high levels of asbestos in the workplace.

You are most likely to be exposed to asbestos by inhaling asbestos fibers which have become suspended in air. Very low levels of asbestos are not likely to be harmful to your health, and low levels can be detected in almost any air sample. These are generally called “background” levels..

To put asbestos risk in perspective, here is a story of a most hazardous asbestos mining operation in Australia, going back to the 1950s:

Working conditions during the operation of the mines and mill at Wittenoom were extremely poor. Employees worked continuously amongst the asbestos dust in the poorly ventilated mine and mill, usually without effective personal protective breathing equipment.

Asbestos Bagging Area

It was generally dirty and dusty; there were clumps of asbestos all over the floor and one’s clothing was rapidly soiled by contact with any surface. Every operation in the mine was associated with dust.

At the bagging plant the floor and the men who stood over the open bags, which were filled from a chute, were covered in clumps of asbestos. In the mill, all tasks were associated with dust.

Workers Bagging Milled Asbestos at the Old Bagging Plant

The dust extraction system removed some of the dust and discharged it above roof level, but it flowed back to the mill and staff offices. The dust was also discharged at the same level as the main entrance to the underground mine, so the air entering the mine already contained dust.

Airborne Asbestos Dust Visible Outside the Mill

The waste material, tailings and remains from the dust extraction system were dumped from hoppers into open trucks and driven further up the gorge, over unsealed roadways and raising clouds of dust. Airline pilots claim they could see the blue haze on the horizon considerable distances away from Wittenoom.

One worker recalled the one hundred-watt light bulbs hanging from the ceiling of the shed looked like candles. You couldn’t recognise a man until you were within a couple of feet of him, because the faces of the workers were coated in dust, like pancake make-up.


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