Workplace health risk assessments

A qualitative WHRA is conducted using a standardised risk matrix, in which the harmfulness and degree of exposure is derived from a pre-determined scale. I use a 5×5 matrix, such as the one in the image below.

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There are a variety of categories of qualitative WHRA. For the purposes of this report, the following categories shall have the associated meanings:

• Formal statutory WHRA’s are the systematic plant-wide assessments typically conducted by a team of appropriately trained individuals.
• Informal WHRA’s conducted by the OH staff, as an adjunct to the formal WHRA’s, in the form of plant walk-throughs (inspections).
• Issue-based WHRA’s are triggered by a specifically identified risk (no incident yet). Examples include the deployment of a pregnant employee into a workplace with potential exposure to hazardous chemicals, and responding to a concern raised by an employee or manager that a particular job may pose a fatigue risk.
• Incident-based WHRA’s which are triggered by incidents (clusters or single), such as employee reported symptoms or occupational disease.

A “quantitative health risk assessment” involves direct measurement of the exposures to the health hazard – usually in the air. This may be called for, depending on the outcomes of the qualitative health risk assessment. This must be done by an appropriately trained professional, usually working within a registered “Approved Inspection Authority”, using sophisticated equipment. These measurements are compared against legal or industry-based reference levels (occupational exposure limits).

Sometimes circumstances require biological monitoring to be included in the quantitative risk assessment. This involves the measurement of the levels of certain workplace chemicals in employees’ biological fluids (most commonly urine, but also blood or breath or even hair).

These exposure levels can be tracked over time, to ensure the exposures improve – see sample graph below.

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The outcomes of these qualitative and quantitative health risk assessment are documented in reports which have legal standing. They include recommendations for actions to be taken, according to the assessment findings.

An important final outcome is a health hazard dashboard, in which the key hazards are summarised by exposure group or job group. This enables the occupational health professional to assign a risk-based medical testing programme for that workplace.

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