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Asbestos

24 July 2004 | Link | Mr John Herbert

Disclaimer

This document is intended for informational purposes ONLY, and may not in any way be interpreted to alter or replace the coverage or requirements of the relevant ordinance.

Asbestos & Construction

In the past asbestos was used widely in construction industry, and its legacy is still with us today.

Unfortunately, the late discovery of Asbestos and or Asbestos Containing Materials (ACM) during the execution of a contract will probably cause delays, complete with the associated extension of time and financial compensation claims.

Choosing the right consultant with old building renovation and refurbishment experience helps reduce the risk, an experienced eye has saved more than one client from the perils of contract delays, claims for extension of time and costs due to late discovery of asbestos on site.

asbestos in buildings, abatement, renovating older buildings 
Chrysotile, white asbestos, Amosite, brown asbestos, Crocidolite, blue asbestos

What is asbestos

Asbestos is a natural mineral. It is mined in much the same way that other minerals, such as iron, lead, and copper. There are many varieties of asbestos, the three of the most common are Chrysotile (called also white asbestos), Amosite (called also grey/brown asbestos), and Crocidolite (called also blue asbestos).

Chrysotile asbestos is also known as serpentine because it is found in serpentine rock. Chrysotile fibres are pliable and cylindrical, and often arranged in bundles, whereas Amosite and Crocidolite fibres are like tiny needles.

Unlike most minerals, which transform into dust particles when crushed, asbestos does not, it fractures into very fine fibres, too small to be seen by the human eye. These fine fibres can float in the air and could be inhaled.

Often individual fibres are mixed with a material that binds them together, creating what is know as ACM (Asbestos Containing Material).

Why was asbestos used?

Asbestos appealed to manufacturers and builders for a variety of reasons. Before the health problems were discovered it was considered a super material, providing combination of desirable properties. It is strong yet flexible, will not burn, it conducts electricity poorly, corrosion resistant, and is a very effective insulator.

Before the health risk was understood Asbestos was widely used because few other available substances could provide these characteristics.

How many products contain asbestos?

One study estimated that 3,000 different types of commercial products contained asbestos. The amount of asbestos in each product varied from as little as one percent to as much as 100 percent.

Many older plastics, paper products, brake linings, floor tiles and textile products contain asbestos, as do many heavy industrial products such as sealants, cement pipe, pipe gaskets, cement sheets, and thermal insulation.

How long has asbestos been in use?

Asbestos was first used to insulate steam engines, however it was until the early 1940's when asbestos was used extensively.

After World War II, and for the next thirty years, people who constructed and renovated buildings, including schools and other public buildings used asbestos and ACM extensively.

They used ACM primarily to fireproof, insulate, soundproof, and decorate. The US the Environmental Protection Agency estimates that ACM is in most of the USA approximately 107,000 primary and secondary schools and 733,000 public and commercial buildings. Asbestos us is global, and was widely employed, in the UK ACM are found in thermal piping insulation, and boiler houses.

Asbestos is commonly found in older buildings, particularly because it was used extensively on the engineering services as thermal insulation.

How are people exposed to asbestos?

Sealed asbestos fibres cause no harm, however still require cautious handling.

The potential hazard occurs when the fibres are released and free to float in the air, where people can inhale them. There are three exposure vectors:

  • occupational
  • paraoccupational
  • neighbourhood

Occupational exposure occurs when people whose work brings them into contact with asbestos. For example workers who renovate buildings containing asbestos materials. Para-occupational exposure occurs when fibres are released from the clothes of a worker exposed to asbestos, and family members inhale asbestos materials. Neighbourhood exposure occurs when people who live or work near asbestos-related operations inhale asbestos fibres that have been released into the air by the operation.

The amount of asbestos a worker is exposed to will vary according to

  • The concentration of fibres in the air
  • Duration of exposure
  • Breathing rate (manual labourers breathe faster)
  • Weather conditions
  • The protective devices the worker wears

It is estimated that between 1940 and 1980, 27 million Americans had significant occupational exposure to asbestos. People may also ingest asbestos if they eat in areas where there are asbestos fibres in the air.

When is ACM most likely to release asbestos fibres?

Damaged ACM is more likely to release fibres than non-damaged ACM. In a 1984 survey, EPA USA found that approximately 66 percent of those buildings that contained asbestos contained damaged ACM.

If ACM, when dry, can be crumbled by hand pressure, a condition known as "friable" it is more likely to release fibres than if it is "non-friable."

Fluffy, spray-applied asbestos fireproofing material is considered "friable."

Some materials which are considered "non-friable," such as vinyl-asbestos floor tile, can also release fibres when sanded, sawed or otherwise aggressively disturbed.

Materials such as asbestos cement pipe can release asbestos fibres if broken or crushed when buildings are demolished, renovated or repaired.

ACM which is in a heavy traffic area, and which is therefore often disturbed, is more likely to release fibres than ACM in a relatively undisturbed area.

How can asbestos be identified?

While it is often possible to suspect that a material or product contains asbestos by visual determination, actual determination can only be made by laboratory analysis.

Until suspect material is tested, prudence dictates treating the product or material as containing asbestos, unless the label, or the manufacturer verifies that it does not. If not friable, take precautions to avert any disturbance.

The EPD requires that the asbestos content of suspect materials be determined by collecting bulk samples and analyzing them using PLM (polarized light microscopy). The PLM technique determines both the percent and type of asbestos in the bulk material.

Does asbestos exposure cause health problems?

Yes. Once inhaled, asbestos fibres can easily penetrate body tissues. They may be deposited and retained in the airways and lung tissue. Because asbestos fibres remain in the body, each exposure increases the likelihood of developing an asbestos-related disease.

Asbestos related diseases may not appear until years after exposure. Today we are seeing results of exposure among asbestos workers during World War II. A medical examination which includes a medical history, breathing capacity test and chest x-ray may detect problems early. Scientists have not been able to develop a "safe" or threshold level for exposure to airborne asbestos. Ingesting asbestos may be harmful, but the consequences of this type of exposure have not been clearly documented. Nor have the effects of skin exposure to asbestos been documented. People who touch asbestos may get a rash similar to the rash caused by fibreglass.

What illnesses are associated with asbestos exposure?


Asbestosis

Asbestosis is a serious, chronic, non-cancerous respiratory disease. Inhaled asbestos fibres aggravate lung tissues, which causes them to scar. Symptoms of asbestosis include shortness of breath and a dry crackling sound in the lungs while inhaling. In its advanced stages, the disease may cause cardiac failure.

There is no effective treatment for asbestosis; the disease is usually fatal. The risk of asbestosis is minimal for those who do not work with asbestos; the disease is rarely caused by neighbourhood or para-occupational exposure.

However, those who renovate or demolish buildings that contain asbestos may be at significant risk, depending on the nature of the exposure and precautions taken.

Lung Cancer

Lung cancer causes the largest number of deaths related to asbestos exposure. The incidence of lung cancer in people who are directly involved in the mining, milling, manufacturing and use of asbestos and its products is much higher than in the general population. The most common symptoms of lung cancer are coughing and a change in breathing. Other symptoms include shortness of breath, persistent chest pains, hoarseness, and anaemia.

Mesothelioma

Mesothelioma is a rare form of cancer which most often occurs in the thin membrane lining of the lungs, chest, abdomen, and (rarely) heart. About 200 cases are diagnosed each year in the United States. Virtually all cases of mesothelioma are linked with asbestos exposure. Approximately 2 percent of all miners and textile workers who work with asbestos, and 10 percent of all workers who were involved in the manufacture of asbestos-containing gas masks, contract mesothelioma.

People who work in asbestos mines, asbestos mills and factories, and shipyards that use asbestos, as well as people who manufacture and install asbestos insulation, have an increased risk of mesothelioma.

So do people who live with asbestos workers, near asbestos mining areas, near asbestos product factories or near shipyards where use of asbestos has produced large quantities of airborne asbestos fibres.

The younger people are when they inhale asbestos, the more likely they are to develop mesothelioma. This is why enormous efforts are being made to prevent school children from being exposed.

Other Cancers

Evidence suggests that cancers in the esophagus, larynx, oral cavity, stomach, colon and kidney may be caused by ingesting asbestos. For more information on asbestos-related cancers, contact your local cancer Society.

Who regulates asbestos?

In Hong Kong the Environmental Protection Department (EPD) are primarily responsible for regulating environmental exposure and protecting workers from asbestos exposure. EPD is responsible for developing and enforcing regulations necessary to protect the general public from exposure to airborne contaminants that are known to be hazardous to human health.

People who plan to renovate or remove asbestos from a building, or who plan to demolish any building, are required to notify the EPD, and comply with the relevant ordinance requirements for assessment, removal, transport and disposal of asbestos and asbestos containing material (ACM).

Particular care should must be exercised during removal of unauthorised building works (UBW), which may contain ACM's.

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