skills/wsh-risk-assessment/references/core-methodology.md

# Workplace Safety and Health Risk Assessment Methodology Knowledge Base

## Based on Singapore Code of Practice on Workplace Safety and Health (WSH) Risk Management (Third Revision, 2021)

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# Purpose

This knowledge base provides reference material on the methodology of Hazard Identification, Risk Evaluation, and Risk Control used in workplace risk assessments.

The objective of risk assessment is to systematically identify hazards, evaluate the associated risks, and implement suitable controls to eliminate or reduce risks to As Low As Reasonably Practicable (ALARP).

Risk assessment should be applied to all work activities, including routine work, non-routine work, research activities, laboratory operations, workshops, fieldwork, events, office work, maintenance activities, contractor work, laser operations, work involving ionising or non-ionising radiation sources, biological work, and all stages of chemical use.

For chemical-related activities, risk assessment should consider the entire chemical lifecycle, including:

* Procurement and acquisition
* Transportation and delivery
* Receiving and inspection
* Storage and segregation
* Dispensing and transfer
* Preparation and mixing
* Experimental use or process use
* Sampling and analysis
* Cleaning and decontamination
* Maintenance involving chemical residues
* Waste collection and disposal
* Spill response and emergency management
* Decommissioning and disposal of contaminated equipment

For biological-related activities, risk assessment should consider the entire biological materials lifecycle, including:

* Acquisition and receipt of biological materials
* Storage and inventory management
* Culture, propagation, or amplification
* Experimental manipulation
* Transport within and between facilities
* Sample processing and analysis
* Decontamination and disinfection
* Waste handling and disposal
* Spill response and exposure management
* Decommissioning of contaminated equipment and facilities

For ionising radiation-related activities, risk assessment should consider the entire radiation source lifecycle, including:

* Procurement and acquisition of radioactive materials or radiation-generating equipment
* Licensing, registration, and regulatory compliance requirements
* Receiving and inspection
* Storage and security of radioactive sources
* Source preparation and experimental use
* Irradiation, imaging, or analytical activities
* Transport within and between facilities
* Maintenance and servicing of radiation-generating equipment
* Contamination monitoring and radiation surveys
* Decontamination activities
* Radioactive waste collection, storage, and disposal
* Radiation incident response and emergency management
* Decommissioning and disposal of radioactive sources or contaminated equipment

For non-ionising radiation-related activities, risk assessment should consider the entire equipment and operational lifecycle, including:

* Procurement and acquisition of non-ionising radiation equipment
* Installation, commissioning, and testing
* Alignment, calibration, and setup activities
* Routine operation and experimental use
* Maintenance and servicing
* Access control and area management
* Exposure monitoring where applicable
* Equipment modification or upgrades
* Incident response and emergency procedures
* Decommissioning and disposal of equipment

Examples of non-ionising radiation activities include:

* Laser systems and optical devices
* Ultraviolet (UV) radiation sources
* Infrared (IR) radiation sources
* Radiofrequency (RF) and microwave equipment
* Magnetic field-generating equipment such as MRI systems
* High-intensity light sources and phototherapy equipment

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# Fundamental Risk Assessment Principles

Risk assessment should:

* Be systematic and evidence-based.
* Consider all foreseeable hazards.
* Consider both safety and health hazards.
* Consider routine and non-routine activities.
* Consider human and organisational factors.
* Consider existing controls already in place.
* Prioritise elimination and prevention of hazards.
* Follow the Hierarchy of Control.
* Be reviewed when activities, equipment, personnel, chemicals, biological agents, or conditions change.

Risk assessment is not merely a documentation exercise. It is a decision-making process to identify and manage risks before harm occurs.

For chemical activities, risk assessment should consider:

* Chemical hazards and physical hazards.
* Acute and chronic health effects.
* Normal operations and foreseeable abnormal situations.
* Potential incompatibilities between chemicals.
* Potential for fire, explosion, runaway reactions, or toxic releases.
* Exposure during storage, handling, transport, use, and waste disposal.
* Information from Safety Data Sheets (SDS), labels, technical literature, and regulatory requirements.

For biological activities, risk assessment should consider:

* Pathogenicity and virulence.
* Routes of transmission.
* Infectious dose.
* Host susceptibility.
* Environmental persistence.
* Potential for aerosol generation.
* Availability of prophylaxis or treatment.
* Containment requirements.
* Exposure during handling, transport, storage, and disposal.
* Information from biosafety manuals, agent risk group classifications, and regulatory requirements.

For ionising radiation activities, risk assessment should consider:

* Type of radiation source (e.g., alpha, beta, gamma, X-ray, neutron).
* Activity, energy, and dose rate of the source.
* External and internal exposure pathways.
* Duration, frequency, and proximity of exposure.
* Potential for contamination and spread of radioactive material.
* Shielding, containment, and engineering controls.
* Access control and security of radioactive sources.
* Radiation monitoring and dosimetry requirements.
* Waste management, storage, transport, and disposal of radioactive materials.
* Regulatory licensing requirements and radiation protection programme requirements.

For non-ionising radiation activities, risk assessment should consider:

* Type of radiation source (e.g., laser, ultraviolet, infrared, radiofrequency, microwave, magnetic field).
* Wavelength, power, intensity, and exposure duration.
* Potential exposure to eyes, skin, or other sensitive tissues.
* Direct beam, reflected beam, and scattered radiation hazards.
* Accessibility of radiation sources during operation, maintenance, and alignment activities.
* Engineering controls such as enclosures, interlocks, shielding, and beam stops.
* Administrative controls including controlled access, signage, and safe work procedures.
* Competency and training requirements for users.
* Use and suitability of personal protective equipment where required.
* Applicable regulatory requirements, standards, and institutional safety procedures.

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# Hazard Identification

## Definition

A hazard is anything with the potential to cause injury, ill-health, environmental damage, property damage, operational disruption, or loss.

Hazard identification is the process of systematically identifying all foreseeable hazards associated with a work activity.

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## Hazard Identification Approach

For each work activity:

1. Define the work activity.
2. Break the activity into logical sub-activities or work steps.
3. Identify foreseeable hazards associated with each step.
4. Identify who may be exposed.
5. Identify how exposure may occur.
6. Determine potential consequences.

For chemical and biological activities, hazard identification should evaluate each stage of the material use process rather than focusing only on the experimental or operational step.

Example:

Chemical use process:

* Receiving concentrated nitric acid
* Transporting to laboratory
* Storage in corrosives cabinet
* Dispensing into smaller containers
* Mixing with other reagents
* Experimental use
* Waste collection
* Waste disposal

Each step may present different hazards and require different controls.

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Biological use process:

* Receiving biological samples or cultures
* Transporting to laboratory
* Storage in designated biological storage units
* Preparation and aliquoting of samples
* Experimental handling and manipulation
* Incubation or cultivation
* Decontamination of work surfaces and equipment
* Collection of biological waste
* Disposal of biological waste

Each step may present different hazards and require different controls.

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Ionising radiation use process:

* Receiving radioactive materials or sources
* Transporting to authorised radiation areas
* Storage in approved radioactive material storage facilities
* Preparation and dispensing of radioactive materials
* Experimental use involving radioactive sources or irradiating equipment
* Monitoring for contamination and radiation exposure
* Collection and segregation of radioactive waste
* Storage of radioactive waste pending disposal
* Disposal through authorised radioactive waste management processes

Each step may present different hazards and require different controls, including exposure to ionising radiation, contamination risks, and regulatory compliance requirements.

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Non-ionising radiation use process:

* Installation or setup of non-ionising radiation equipment (e.g., lasers, UV sources, RF or microwave equipment)
* Inspection and verification of safety features
* Alignment, calibration, or testing activities
* Experimental operation of equipment
* Maintenance or adjustment activities
* Shutdown and securing of equipment
* Storage of portable radiation-emitting devices where applicable

Each step may present different hazards and require different controls, including exposure to optical radiation, ultraviolet radiation, electromagnetic fields, thermal effects, and reflected or scattered radiation.

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