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5 ASSESSMENT OF HEALTH RISKS
5.1 Introduction
The primary reason for conducting a workplace assessment is to assess the risks to the health of employees. Where a less than satisfactory situation is
indicated there will be an additional requirement: To specify steps to achieve adequate control.
To identify any other action that is required.
5.2 Hazard and Risk
When undertaking risk assessments, it is important to have a clear understanding of the differences between hazard and risk.
A hazard is something that can cause harm if not controlled. The outcome is the harm that results from an uncontrolled hazard.
A risk is a combination of the probability that a particular outcome will
occur and the severity of the harm involved.
5.3 Assessment of Health Risks
The process of assessing risks to health can be broadly described by the flow diagram below.
Define the extent of the assessment Gather Information
Assess Exposure
Review the Assessment Record the Assessment
Carry Out Actions Identify Actions
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5.3.1 Define the extent of the assessment
At first it is necessary to define the process or activity which is being assessed. This may involve one or more activities as well as one or more
workers at a time. It may also be necessary to assess different hazards as part of different assessments, e.g. noise assessments are usually conducted
separately from chemical risk assessments as they involve very different approaches. However, when assessing hazards from chemicals such as
solvents it is often possible to group any chemicals under one assessment, as they possess similar properties and require similar controls.
5.3.2 Gather Information
An assessment of the health risks in the workplace necessitates an appreciation of a number of factors in the decision making process, including
some or all of the following, as appropriate - and therefore as a first step information pertaining to these factors has to be gathered if a meaningful
assessment is to be undertaken: The nature of the process or operation, e.g. continuous or batch, indoor
or outdoor. The substances used and produced chemical, biological plus other
agents noise, radiation and factors ergonomic present. For the substances, some may be expressed as trade names and their
chemical composition will need to be understood. It is also important to remember that most industrial exposures to
chemicals inhalation, skin contact are to mixtures, not to single substances. In these cases, information about the mixture composition
will need to be known. The form of the substances gases, vapours etc. and other agents plus
a knowledge of where these are present in the workplace locationtask undergoing assessment.
An understanding of the effects of the relevant agentsfactors chemical, physical, biological, ergonomic on the body.
A knowledge of the types of job carried out e.g. operator, maintenance, supervisory, laboratory and the elements of those jobs
53 for which higher exposures to chemical, physical or biological agents or
an adverse ergonomic situation, may occur. Exposure estimates and their magnitude in relation to any relevant
occupational exposure limits that may have been promulgated. The types and extent of occupational exposures.
Workshift pattern. The recommended operating practices and precautionary measures
incl. engineering control. Worker health experiences, e.g. check whether there arehave been
any cases of occupational ill-health, incidents, complaints or compensation claims.
Any other relevant information. There is a need, for example, to put observations, data etc., in perspective and to ascertain how typical they
are as compared to normal practices and procedures. The existence of inventoriesregisters of substances, non-chemical agents
e.g. noise and radiation sources and the types of job undertaken can be extremely useful in progressing an assessment.
The availability of relevant sources of information can also be of considerable advantage, e.g.
Material safety data sheets MSDSs. Manufacturers labelling.
ACGIH TLV documentation. Other published e.g. national, company, trade association, technical
and unpublished sources.
5.3.3 Assess the Health Risks
Having gathered all the relevant information, the actual assessment is now carried out. This involves keen inquiry and observation, for example, in
relation to the operating practices and precautionary measures actually adopted in a specific task, and, where necessary, environmental
measurement e.g. personal exposure monitoring.
54 Remember to ask about the existence and application of a work permit
system and to check the scope and effectiveness of its application from a health protection viewpoint.
An assessment should be suitable and sufficient. Clearly, therefore, it should be conducted by a competent person and the type of individual that
constitutes such a person will vary from one workplace to another. In some cases the assistance of a fully qualified occupational hygienist will be
necessary because of the more complex nature of the risks being investigated.
A critical point to be appreciated is that the term assessment is not synonymous with the measurement or monitoring of occupational
exposures, but embraces wider considerations, such as the factors already referred to, as well as relevant inquiry about, and keen observation of, the
jobstasks under scrutiny. On the other hand, the findings from measurements of occupational
exposures to chemical, physical or biological agents in the workplace may form an important element of the overall assessment. In other cases such
monitoring is unnecessary or inappropriate.
Workplace Monitoring
It may be necessary to obtain some monitoring data, particularly regarding exposure levels, as part of the overall assessment of health risks. Where
workplace monitoring is required, the aim is to assist in ensuring the health protection of employees and the sampling strategy adopted should be
appropriate to the basic reason for the type of survey to be conducted. The latter ranges from initial monitoring of a plant or operation, in order to establish
a baseline situation, to the periodic monitoring of a plant or operation in order to check, at regular intervals, that acceptable conditions are being maintained.
5.3.4 Specify Any Action Required
Where the assessment indicates a risk to health, it is necessary to specify the steps to be taken to achieve effective control. This is an important, integral
55 part of the assessment, which is NOT deemed to have been completed
without this aspect being addressed.
5.3.5 Record the Risk Assessment
Although assessments are important in the preventative approach to health protection, they are only of limited value unless they are recorded in writing,
and dated and signed by the assessor. The quality of an assessment is also likely to be enhanced when verification of verbal information pertaining to
fundamental aspects of the assessment can be obtained, in one form or another, and documented.
5.3.6 Carry out the Actions
It is important to ensure that recommendations from any assessment are implemented properly. Many assessments fail to control exposure because
the actions are not implemented.
5.3.7 Review the Risk Assessment
The initial assessment should not be regarded as being relevant forever. Periodic re-assessments should be undertaken regularly and in any event
whenever it is suspected that the assessment is no longer valid. The following are the types of factor that should trigger such a further assessment
of the health risks in the latter situation: Significant changes to:
The substancesagents involved andor their sources. The plant e.g. modified engineering control.
The process or method of work. The volume or rate of production.
Adverse results from: Personal exposure monitoring.
Health surveillance monitoring e.g. eudiometry, biological monitoring. Monitoring of process control e.g. fugitive emissions.
Cases of occupational disease.
56 New information on the risks to health of chemical, physical or biological
agents. In the absence of known changesadverse resultscasesnew information the
period between reassessments should depend upon the nature of the risks, the work and a judgement on the likelihood of changes occurring. In any
event it is suggested that all assessments should be reviewed at least every two years.
5.4 Expert Systems and Control Banding
There are a number of expert systems which have been developed to assist employers in undertaking health risk assessments. These systems all use an
approach called “Control Banding”. Control banding involves the following steps.
Hazard Classification – Hazard characteristics such as risk phrases, OELs
and hazard descriptions are used to classify the materials into groups or hazard bands.
Assessment of exposure potential – Simplified models are used to assess
the level of exposure for the task without conducting exposure monitoring.
Selection of control approach – These are automatically selected using pre-
determined rules and guidelines. Depending upon the control banding approach adopted the rules and guidelines will have been generated and
verified by a significant number of qualified occupational hygienists. The control approach is described by selecting a document from a pre-written
library of guidance sheets. The ILO toolkit is an example of one of the control banding approaches. The
toolkit is an internet based programmed and can be accessed via the ILO web site at:
http:www.ilo.orglegacyenglishprotectionsafeworkctrl_bandingtoolkiticcti ndex.htm
accessed February 2010.
57 The ILO toolkit was originally developed from the UK‟s COSHH Essentials
which can be accessed at http:www.coshh-essentials.org.uk
accessed February 2010.
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6 MEASUREMENT OF AIRBORNE CONTAMINANTS
6.1 General Principles