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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.
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.