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used to determine compliance with National or other worker exposure limits and determine
what controls are required to remain within the limits. Monitoring can establish if current
controls are adequate to limit exposure and assist in choosing appropriate personal protective
equipment (PPE). Monitoring can provide information on patterns of exposure and levels of
risk that managers can use and provide to workers. It can also indicate the need for health
surveillance of groups and individual workers.

Limitations of Hazardous Substance Monitoring
As described previously, the health effects of exposure to toxic substances can be acute or
chronic. It is therefore necessary to use appropriate methods of measurement to distinguish
these effects. It is also important to understand the limitation of any hazardous substance
monitoring method used, for example, the risk of cross contamination of similar substances
being measured and the fact that general workplace monitoring may not represent specific
worker exposure.

Hazardous substance monitoring of the presence of a chemical in the air may not represent
the worker’s complete exposure, for example there may be additional exposure to the
chemical by skin contact or orally through poor hygiene arrangements.

One of the main limitations of hazardous substance monitoring is the competence of the
person conducting the monitoring. It is reliant on them conducting monitoring at the time
that represents real exposure of workers and using methods that will give reliable
measurements.

When carrying out monitoring related to dusts it is important to discern the amount of dust
that can penetrate the airway and cause harm. If the person conducting the monitoring does
not understand the difference between 'total inhalable dust' and 'respirable dust' there is a
risk that unsuitable measurements may be taken.

Total inhalable dust' is the amount of airborne material that enters the nose and mouth
during breathing and is available for deposition in the body. 'Respirable dust' is the amount
of airborne material that penetrates to the gas exchange region of the lung.

General Approach to Hazardous Substance Monitoring
When embarking upon a monitoring campaign to assess the risk to which an individual may
be exposed, it is necessary to ask several questions.

What to sample?

This involves a review of the materials, processes and operating procedures being used
within a process, coupled with discussions with management and health and safety
personnel. A brief 'walkthrough' survey can also be useful as a guide to the extent of

POSHE V2| Unit IG2 – Element 7 – Chemical and Biological 19
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