Introduction to Working Environment Health Risk Assessment (WEHRA)
- I. Caroline V. Holmgard
- 4 hours ago
- 6 min read
In this article:
What is WEHRA?
WEHRA is a powerful, structured, workshop-based method used to identify, assess, and manage health risks in the Working Environment in a systematic manner.
The WEHRA risk model places humans and their work tasks at the core of the assessment, with a particular focus on operation and maintenance activities. Typical Working Environment factors considered in WEHRA are illustrated in Figure 1.
Figure 1 Working Environment factors relevant to occupational safety and health.
The purpose of the risk assessment is to generate results that can be used to improve the existing working environment or to influence the design of future workplaces. The method is interdisciplinary, and it shall involve the end users/operators in the specific workplace who possess task-related knowledge of the area or equipment being assessed.
When is WEHRA Relevant?
WEHRA is relevant whenever there is a need to systematically assess and manage health risks in the working environment. This includes the development of new projects, modifications, acquisitions, operational changes, new equipment, or when new risks, incidents, or findings arise.
A WEHRA is normally performed at major stages of an engineering project, such as concept, FEED (Front End Engineering Design), and EPCIC (Engineering, Procurement, Construction, Installation, and Commissioning). Typical WEHRA activators are shown in Table 1:
Table 1 Typical WEHRA activators. If something changes, something new is built, or new information appears, a WEHRA is to be considered.
Activators for WEHRA update or performance | Examples |
Audit, monitoring, investigation findings or lifetime extensions for existing installations | Results from audits, verifications, or reviews |
Work-related illness (WRI) or incident reports | WRI cases or Synergi incident registrations |
Changes in the working environment | New locations, new plants/offices, commissioning or decommissioning, modifications, new work processes, organizational changes |
Why is WEHRA Beneficial for a Company?
WEHRA is beneficial because it:
Protect workers by providing a systematic approach to identifying and controlling health risks, helping prevent work-related illness and injury.
Ensure end-user involvement, ensuring that planned activities and potential hazards are captured and that the most critical risks are prioritised.
Support compliance with regulatory and company requirements, contributing to a safer and healthier working environment.
Reduce lifecycle costs, as early identification of risks limits the need for costly or disruptive design changes later in the project or, in the worst case, changes after completion.
Description of the WEHRA Method
While WEHRA procedures may vary, the common goal is to ensure that risks related to work tasks and work areas are reliably identified, effectively managed, and controlled through appropriate mitigation measures.
The method described herein can be briefly divided into the following sections:
1) WEHRA planning and preparations
2) WEHRA Workshop
3) WEHRA reporting, follow-up and close-out.
WEHRA planning and preparations
The WE/Safety responsible initiates WEHRA planning and preparation. The planning includes assigning responsibilities by appointing a facilitator and holding a planning meeting. The client, contractor, and facilitator should attend the meeting to evaluate the scope and agree on practical details such as the composition of the WEHRA workshop team, duration, and workshop location. A ToR (Terms of Reference), including a scope presentation and an explanation of the WEHRA methodology, is prepared in advance and distributed to all participants. Relevant background information may include, but is not limited to, WE evaluations, noise maps, illumination drawings, wind‑chill reports, HVAC D&IDs, equipment lists, and vendor documentation; other project- or site-specific documentation should also be considered as needed to focus on the key risk areas and limit the overall scope.
2. Risk assessment workshop and selection of mitigating actions
The risk assessment should always start by presenting the WEHRA method and the scope planned for assessment. The facilitator ensures structured discussions and supports the group in reaching consensus.
The workshop is preferably structured in two parts. In Workshop – Part 1, work activities and their associated hazards are identified, analysed, and assigned a risk score. In Workshop – Part 2, mitigating actions to remove or reduce the risk are discussed and agreed upon.
Workshop – Part 1: Risk Identification and Evaluation
A simplified example of the WEHRA worksheet is shown in Table 2. The worksheet is used to document the workshop process. The worksheet generally includes information such as the area in focus, the equipment involved, the specific activities, the relevant WE hazard, the duration of each activity, and the number of personnel required. In many cases, this first part is completed as thoroughly as possible before the actual workshop begins.
Table 2 Simplified example of the WEHRA worksheet used to document the workshop process.
It is important to distinguish between tasks performed infrequently or for short durations and those that are frequent or long‑term, as this distinction is essential for assessing the level of exposure. Existing controls, whether technical, organisational, or related to the use of personal protective equipment (PPE), should also be described.
The next step is to identify the associated hazards, which may include, for example, chemical exposure, noise, ergonomic strain, hot or cold surfaces, or radiation. These hazards are then evaluated through a risk‑scoring process that considers expected exposure, existing controls, and potential health consequences, to prioritise risks. Different risk matrices or risk-ranking systems may be used depending on the organization. The risk matrix used in this example scores each WE hazard from 0 to 4 using colour coding, as shown in Table 2. The rating shows how well the risk is controlled and what follow‑up is required.
In simplified terms, the risk scores are interpreted as follows:
Score 0: Risk not assessed
Score 1: Low and acceptable risk
Score 2: Risk requiring attention
Score 3: Unacceptable risk - design change or mitigating actions required
Score 4: Risk unknown/insufficiently understood - more information required.
In some cases, a separate score and colour coding may also be used to indicate that the Working Environment is improved compared with similar workplaces or activities.
The work group discusses and agrees on a risk score, obtained from the risk matrix, for each work activity and its associated health hazard, based on knowledge of the task, the relevant hazards, applicable tolerable limit values from regulations and guidance, and expected exposure levels.
Workshop – Part 2: Identification of Mitigating Actions
Based on the risk assessment in Workshop – Part 1, the workshop identifies and prioritises the mitigating actions in Workshop – Part 2. These actions are compiled into a prioritised list, including allocated responsibilities and deadlines for follow‑up. The actions should be formulated in a way that makes the results measurable and verifiable. Mitigating actions should be prioritised according to the hierarchy of controls shown in Figure 2.
Figure 2 Hierarchy of controls used when proposing mitigating measures for working environment health risks. Source: The National Institute for Occupational Safety and Health (NIOSH, United States), modified.
3. WEHRA report, follow-up on actions, and WEHRA close-out report
The final part of the WEHRA process involves preparing the WEHRA report, following up on the agreed mitigating actions, and issuing a close-out report that documents the completed actions and verifies that the risks have been properly managed.
WEHRA Guidewords
Supporting guidewords for the review leader and participants during a WEHRA are shown in Table 3.
Table 3 Supporting guidewords when leading/participating in a WEHRA workshop.
Working Environment Factor | Useful Information / Examples | Mitigating Actions / Controls |
Chemicals | Direct exposure, hazardous chemicals, exhaust, type of exposure, short/long term, open/closed systems, etc. | Elimination, substitution, closed system, remote control, ventilation, safety signs, routing emissions, etc. |
Noise | High impact noise, long-term exposure, peak noise, noise in control rooms/rest areas, etc. | Separation of noise sources, remote control, low noise equipment, damping, noise hoods, absorbents, etc. |
Vibration | Whole body/hand-arm vibration, long-term exposure, main sources | Anti-vibration mounting, structure stiffening, low vibration equipment, remote control, use of robots, etc. |
Ergonomics (arrangement/access) | Workplace design, workload, manual tasks, material handling, static positions, sum of exposures, etc. | Temporary access solutions, automation, robots, lifts, relocation of equipment, fit-for-purpose lifting gear |
Human Factors | Man-machine interface, alarm system design, layout of control centres, roles, responsibilities | Manning study, communication systems, alarm philosophy/layout, control cabin design |
Outdoor Operations and Climate | Comfort, indoor climate issues, air quality, heat/cold stress, weather protection, operative temperature | Good indoor design, ventilation, air conditioning, sun shielding, PPE, job rotation, winterisation, heating |
Illumination | General/task lighting, glare, reflection, shadows, seasonal light risks, emergency lighting | Geometry of light sources, adjustable task lighting, easy cleaning, removal of snow/ice |
Radiation | Ionising radiation, microwaves, lasers, UV/IR, electromagnetic fields, high voltage/amperage equipment | Eliminate source, alternative equipment, shielding, training, procedures |
Biological Hazards | Bacteria, viruses, microorganisms, sewage, contamination risk, poisonous species, biological sewage systems | Hygiene measures, remote control, barriers, training, health follow-up, cleaning utilities |
Psychosocial / Organisational | Workload, roles/responsibilities, support, relations, changes, organisational design, solitary work, control | Alternative tasks, rotation, leadership competence, systematic follow-up, strengthening leadership |
