Asbestos Risk Assessment


Exposure Assessment

The risk due to asbestosis arises from the inhalation of fibres. A visual assessment of the workplace is the first important step. If a workplace looks dusty, no control procedures are in place and no respiratory protection is being used, workers could have excessive exposure to fibres. Correct fibre identification and fibre counting are the minimum requirements needed to assess the risk where asbestos is being used.

The following steps indicate the basic procedures used in assessing the risk due to asbestos fibre exposure.

A. Ascertaining the presence of asbestos in the work place.

Microscopic identification is most commonly used to distinguish asbestos from other fibres. A representative sample is needed for laboratory analysis. There may be more than one kind of fibre in the sample. Enough material should be collected in order to sample all types of fibres present.

B. Identification of the asbestos fibre type.

Crocidolite and amosite are considerably more hazardous than chrysotile, so it is important to know the actual type of fibre dealing with. Ideal techniques available for the identification of asbestos are polarising light microscopy (PLM) and dispersion staining microscopy.

C. Quantity of asbestos in the source.

PLM and dispersion staining method can give some estimates of the asbestos present in the sample. When a mixture of chrysotile and other asbestos fibres is detected, the mixture is usually regarded on the basis of the more hazardous type of fibre.

D. Procedures for handling the material in the workplace.

Using processes that minimise airborne fibre will reduce he risk. Special low speed, high torque tools are available for working asbestos products. Use of wet dust suppressing methods is important, especially for removal processes.

E. Presence of respiratory protection in place.

Control processes are crucial to the safe handling of the asbestos. Methods that prevent dust from escaping are the primary means of control. Respiratory protection is only added when dust control procedures cannot control the fibre release.

Dr. Sunil Kumar Joshi, Norway 2001

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