Hazard Identification and Risk Assessment

Introduction

Industrial safety is not achieved merely by complying with procedures after an accident has occurred. It depends on the systematic anticipation of harm, evaluation of risk, implementation of effective controls, and continuous learning. Hazard identification and risk assessment (HIRA) provide the foundation for this preventive approach.

In production environments, hazards arise from machinery, energy sources, materials, work organisation, human factors and the wider operating context. A maintenance technician may face stored mechanical energy, an operator may encounter a rotating shaft, and a supervisor may be exposed to psychosocial risks created by excessive workload or poor shift design. Effective safety management therefore requires both technical analysis and an understanding of how work is actually performed.

This chapter explains the principal hazard categories and the methods used to identify and control them, including job safety analysis (JSA), HAZID, HAZOP and what-if analysis. It also examines risk matrices, the hierarchy of controls, ALARP, control verification and the managerial responsibilities associated with risk assessment.

Learning Objectives

By the end of this chapter, the learner should be able to:

1. Distinguish between hazards, hazardous events, consequences and risks.
2. Identify physical, mechanical, electrical, chemical, biological, ergonomic and psychosocial hazards.
3. Apply JSA, HAZID, HAZOP and what-if analysis appropriately.
4. Use qualitative and semi-quantitative risk matrices while recognising their limitations.
5. Select controls using the hierarchy of controls and the ALARP principle.
6. Review controls after changes, incidents, near misses or evidence of declining performance.
7. Explain the ethical, legal and managerial significance of competent risk assessment.

1. Fundamental Concepts

A hazard is a source or situation with the potential to cause injury, ill health, damage or loss. Electricity, a corrosive chemical, an unguarded press and excessive workload are examples of hazards. A hazardous event is an occurrence through which the hazard may cause harm, such as contact with an energised conductor or release of compressed gas.

A consequence is the outcome of an event, for example burn, fracture, toxic exposure, production loss or environmental contamination. Risk is the combination of the likelihood of harm and the severity of that harm. Risk assessment is the structured process of identifying hazards, analysing and evaluating risks, selecting controls and recording decisions.

It is important to distinguish risk from danger. Danger is often used informally to describe a serious hazard, whereas risk requires consideration of exposure and consequences. A highly toxic substance in a sealed, remotely operated system may present less operational risk than a moderately harmful solvent used frequently without ventilation.

Risk terminology

• Initial or inherent risk: risk before additional controls are applied.
• Residual risk: risk remaining after controls are implemented.
• Acceptable or tolerable risk: risk judged permissible under defined criteria; it is not necessarily zero.
• Exposure: contact between a person and a hazard, including frequency and duration.
• Interested parties: workers, contractors, visitors, regulators, emergency services, communities and other persons affected by operations.
• Control: a measure that eliminates a hazard or reduces the likelihood or consequence of harm.

A useful conceptual relationship is:

where R is a risk score, L is a rating for likelihood and S is a rating for severity. This is a scoring convention, not a universal physical law. It is applicable when the organisation has defined rating scales and decision thresholds. The product has no meaningful unit and must not be interpreted as an exact probability of injury. In formal quantitative analysis, risk may instead be expressed as expected loss or event frequency, but such estimates require reliable data and explicit assumptions.

For example, if likelihood is rated 3 and severity 4 on a five-point matrix, the score is:

The organisation must determine whether 12 is tolerable and what action is required. Another organisation using different scales may reach a different score for the same situation. Consequently, the reasoning behind the rating is more important than the numerical score alone.

2. Categories of Industrial Hazards

2.1 Physical hazards

Physical hazards arise from environmental conditions or forms of energy. They include noise, vibration, heat, cold, radiation, poor illumination, pressure, slips and falls. Excessive noise may cause hearing loss even when no immediate discomfort is reported. Whole-body vibration can contribute to fatigue and musculoskeletal disorders, while ionising radiation can damage tissue and genetic material.

Identification should consider intensity, duration, frequency, vulnerable persons and interactions. For example, heat stress is influenced not only by air temperature but also by humidity, radiant heat, clothing, workload, acclimatisation and access to hydration.

2.2 Mechanical hazards

Mechanical hazards result from moving or stored mechanical energy. Typical sources include:

• entanglement at rotating shafts and couplings;
• crushing between fixed and moving parts;
• shearing at cutting edges;
• drawing-in at rollers and belts;
• impact from ejected components;
• falling objects and suspended loads; and
• unexpected movement during maintenance.

Guarding, interlocking, safe distances, isolation and competent maintenance are central controls. A guard that can be easily defeated, removed or bypassed is not a reliable control unless its use is supported by design, supervision and verification.

2.3 Electrical hazards

Electrical hazards include electric shock, arc flash, burns, fire, unexpected start-up and static discharge. Risk depends on voltage, available fault current, energy, approach distance, environmental conditions, equipment condition and the effectiveness of isolation.

Electrical work requires competent persons, suitable equipment, inspection, earthing or grounding, overcurrent protection and an energy-control procedure. Lockout/tagout or an equivalent isolation system must address all energy sources, including backfeeds, capacitors, batteries and automatically controlled systems. A test for dead is essential; switching off a control panel is not proof that equipment is de-energised.

2.4 Chemical hazards

Chemical hazards may be acute or chronic. They include toxicity, corrosivity, flammability, oxidising properties, sensitisation, carcinogenicity and dangerous reactions. Identification should use current safety data sheets, labels, inventories, exposure information, process conditions and worker knowledge.

The assessment should consider routes of entry: inhalation, skin absorption, ingestion and injection. Controls may include substitution, closed transfer, local exhaust ventilation, segregation of incompatible substances, spill containment, safe storage, hygiene facilities and emergency eyewash or shower systems. Personal protective equipment (PPE) is important but should not compensate for avoidable failures in process design.

2.5 Biological hazards

Biological hazards include bacteria, viruses, fungi, parasites, allergens, contaminated sharps, animal products and biological waste. They may occur in food production, wastewater treatment, healthcare-related operations, laboratories and cleaning activities.

Controls include hygiene, vaccination where appropriate, containment, disinfection, safe sharps handling, ventilation, waste management and exposure-response procedures. A risk assessment must consider vulnerable workers, such as immunocompromised persons, and must avoid stigma or unjustified disclosure of personal health information.

2.6 Ergonomic hazards

Ergonomic hazards result from a mismatch between work demands and human capability. Examples include forceful exertion, repetition, awkward posture, manual handling, prolonged standing, poorly designed controls and inadequate recovery time.

Assessment should examine the task, load, posture, frequency, duration, work rate, variability and worker feedback. Effective controls include redesigning the workstation, reducing load weight, using mechanical aids, changing layout, varying tasks and allowing adequate recovery. Training in lifting technique alone is usually weaker than redesigning the task to remove excessive manual handling.

2.7 Psychosocial hazards

Psychosocial hazards arise from the design and management of work and from social interactions. They include excessive demands, low control, inadequate support, bullying, harassment, violence, role ambiguity, insecure work, poor consultation, fatigue and poorly managed shift work.

These hazards can contribute to stress, sleep disturbance, errors, depression, cardiovascular disease and unsafe decision-making. Assessment should involve confidential worker participation and examine organisational causes rather than blaming individuals. Controls may include realistic staffing, improved rostering, clear roles, respectful conduct systems, supervisor training, fatigue management and accessible reporting mechanisms.

3. The Risk Assessment Process

A robust HIRA normally follows these stages:

1. Define the scope, task, location, operating mode and affected persons.
2. Gather information through observation, drawings, procedures, incident data, safety data sheets and worker consultation.
3. Identify hazards and credible hazardous events.
4. Determine existing controls and their reliability.
5. Analyse likelihood, consequence and exposure.
6. Evaluate the risk against organisational and legal criteria.
7. Select additional controls using the hierarchy of controls.
8. Assign owners, deadlines and verification methods.
9. Communicate the results and implement the controls.
10. Review the assessment after change, incident, near miss, audit finding or a defined time interval.

The assessment should cover normal, abnormal, start-up, shutdown, cleaning, maintenance, emergency and reasonably foreseeable non-routine conditions. It should also include contractors, visitors, inexperienced workers and people who may be especially vulnerable.

4. Hazard Identification Techniques

4.1 Job Safety Analysis

JSA, also called job hazard analysis, divides a job into logical steps. For each step, the team identifies hazards, possible consequences and controls. It is especially useful for discrete tasks such as changing a die, clearing a jam or replacing a pump seal.

A practical JSA table may contain:

JSA is task-focused and accessible, but it may overlook interactions between systems or wider organisational conditions. It should not become a paperwork exercise completed without observing the real task.

4.2 HAZID

HAZID is a structured, high-level hazard identification study. A multidisciplinary team considers plant areas, materials, energy sources, operating conditions, external events and human factors. Guidewords such as “loss of containment,” “loss of power,” “wrong material,” “vehicle impact” and “simultaneous operations” stimulate discussion.

HAZID is useful during concept, design, installation and major change. It provides breadth rather than detailed analysis of every control loop. Its output should include hazards, causes, consequences, safeguards, recommendations and responsible owners.

4.3 HAZOP

HAZOP is a systematic examination of a process design using guidewords applied to parameters. Common guidewords include No, More, Less, As well as, Part of, Reverse and Other than. Parameters may include flow, pressure, temperature, level, composition and sequence.

For example, applying “More flow” to a solvent feed node may identify overfilling, increased vapour release, downstream pressure rise and possible flammable atmosphere. The team then records causes, consequences, existing safeguards and recommendations.

HAZOP is strongest for well-defined, continuous or batch processes with adequate drawings and a competent team. It is time-consuming and may be less suitable for simple manual tasks or poorly defined early concepts.

4.4 What-if analysis

What-if analysis uses questions such as:

• What if the cooling water fails?
• What if the wrong chemical is connected?
• What if the guard is removed during production?
• What if a worker enters during automatic restart?

It is flexible and efficient, particularly for modifications and smaller systems. However, its quality depends heavily on the experience and imagination of the team. A checklist can improve consistency.

4.5 Checklists, audits and worker consultation

Checklists help verify known requirements, while inspections and audits reveal deteriorating conditions. Worker consultation is essential because operators often understand informal workarounds, intermittent faults and practical barriers that are absent from procedures. Consultation must be meaningful: workers should be able to influence decisions without fear of retaliation.

5. Risk Analysis and Risk Matrices

A common matrix uses five likelihood levels and five consequence levels. Likelihood descriptions may range from rare to almost certain; consequence descriptions may range from minor first aid to multiple fatalities or catastrophic loss. The matrix then assigns bands such as low, medium, high and extreme.

This matrix is illustrative. An organisation must define its own categories and action rules. A high severity with low likelihood may still require urgent attention, particularly where evidence is weak or consequences are irreversible.

Risk matrices have limitations. They can create false precision, hide uncertainty, encourage manipulation of ratings and treat the product of ordinal categories as if it were a true measurement. They also struggle with multiple fatalities, common-cause failures and risks that are low-frequency but catastrophic. Good practice therefore records the scenario, assumptions, evidence, uncertainty and rationale—not merely a colour or score.

6. Hierarchy of Controls and ALARP

Controls should be selected in the following order:

1. Elimination: remove the hazardous task or energy source.
2. Substitution: replace it with a less hazardous material, process or method.
3. Engineering controls: physically separate people from the hazard through guarding, enclosure, interlocks, ventilation or automation.
4. Administrative controls: procedures, permits, scheduling, training, supervision, signs and communication.
5. PPE: respirators, gloves, eye protection, hearing protection, protective clothing and fall protection.

Controls near the top generally provide more reliable protection because they depend less on human behaviour. Several layers may be required, but lower-level controls must not be used to justify failing to consider elimination or engineering solutions.

ALARP means “as low as reasonably practicable.” It requires risk reduction until further reduction would involve a grossly disproportionate sacrifice compared with the safety benefit, considering the seriousness of harm, available technology, good practice, cost and knowledge. ALARP does not mean “as cheap as possible,” nor does financial cost automatically justify retaining a significant risk. The burden of demonstrating that further reasonable reduction is not practicable normally rests with the duty holder.

A control should be evaluated for effectiveness, independence, availability, maintainability and human reliability. For example, an interlocked guard may be effective only if the interlock is fail-safe, tested, difficult to defeat and included in preventive maintenance.

7. Worked Application: Clearing a Packaging-Line Jam

The following is an illustrative case.

Background and problem

A packaging line stops when cartons become misaligned. Operators sometimes open a guard and reach into the conveyor to remove the obstruction. The conveyor can restart automatically when a sensor resets. A preliminary assessment rates the consequence as 4 (major) and likelihood as 4 (likely), giving a score of 16 under the illustrative matrix.

Analysis

The hazard is moving mechanical equipment. The hazardous event is hand entry into the nip point followed by unexpected restart. Possible consequences include crushing, amputation and psychological trauma. Contributing factors include production pressure, inadequate jam-clearing design, unclear isolation requirements, poor visibility of the obstruction and reliance on operator action.

Solution using the hierarchy

• Elimination: redesign the infeed to prevent carton misalignment.
• Substitution: use a low-energy clearing mechanism rather than manual reach-in.
• Engineering: install fixed or interlocked guards, a trapped-key system, accessible emergency stops and a controlled zero-energy clearing mode.
• Administrative: define a jam-clearing procedure, authorise competent persons, provide training and prohibit bypassing.
• PPE: use suitable hand and eye protection, while recognising that PPE cannot prevent crushing at a nip point.

The assessment should also address pneumatic pressure, gravity, stored spring energy and automatic restart from upstream equipment. After installation, the team should test the interlock, verify that restart is impossible during access, observe actual operator behaviour and review near-miss data. A revised risk rating is not sufficient evidence by itself; the control must be demonstrated to work.

Outcome and learning points

The central lesson is that the original risk was not primarily a training problem. The task design invited exposure. A reliable engineering solution, supported by procedure and verification, is more defensible than instructing workers simply to be careful.

8. Management, Governance and Ethical Issues

Risk assessment is a management responsibility, not merely a safety department activity. Production, engineering, maintenance, procurement, human resources and contractors all influence risk. Procurement decisions should consider guarding, maintainability, noise, chemical compatibility, spare parts and supplier information before equipment is purchased.

Assessments must be competent, current and proportionate. They should be reviewed when equipment, materials, staffing, software, layout, production rate or procedures change. Management of change should identify new hazards and confirm that existing safeguards remain valid.

Ethically, organisations must protect workers even when incidents are statistically rare. Reporting systems should encourage near-miss and hazard reporting without retaliation. Personal medical and psychosocial information must be handled confidentially. Safety performance indicators should not reward under-reporting; a fall in reported incidents may indicate improvement, concealment or reduced reporting.

Legal requirements vary by jurisdiction, but commonly include duties to provide safe systems of work, competent supervision, information, training, suitable equipment, emergency arrangements and consultation. Company standards should not be treated as a substitute for applicable law or professional judgement.

9. Technology and Contemporary Practice

Digital tools can strengthen HIRA when they improve evidence and decision quality. Sensors may monitor vibration, temperature, gas concentration or machine access. Computerised maintenance systems can link hazards to work orders, permits and inspection records. Digital twins and simulation can test layouts and abnormal conditions before commissioning.

Artificial intelligence may assist in analysing incident narratives, detecting patterns in inspection records or identifying likely hazards from images. However, AI outputs require competent human review. Models may be trained on incomplete data, reproduce historical bias, miss rare events or provide confident but incorrect classifications. Accountability remains with the organisation and responsible professionals. Automation should therefore support—not replace—worker consultation, site observation and engineering judgement.

10. Best-Practice Review Checklist

Before approving an assessment, ask:

• Is the scope and operating mode clearly defined?
• Were workers and relevant technical disciplines involved?
• Were non-routine, maintenance and emergency conditions considered?
• Are hazards described as credible events rather than vague labels?
• Are existing controls distinguished from proposed controls?
• Is the risk reasoning supported by evidence?
• Were higher-order controls considered before PPE?
• Are responsibilities, deadlines and verification criteria assigned?
• Has human error, fatigue, contractor work and simultaneous operations been considered?
• Is residual risk communicated and accepted by the authorised person?
• Is a review trigger or review date specified?

Chapter Summary

Hazard identification and risk assessment are preventive processes used to understand how work can cause harm and to select controls before failure occurs. Hazards may be physical, mechanical, electrical, chemical, biological, ergonomic or psychosocial. Effective assessment considers people, equipment, materials, energy, tasks, environment and organisational conditions across normal and abnormal operations.

JSA is appropriate for detailed task analysis; HAZID provides broad multidisciplinary identification; HAZOP examines process deviations using guidewords; and what-if analysis explores credible failure scenarios through structured questions. Risk matrices support consistent decisions but are qualitative or semi-quantitative tools, not precise measures of probability.

The hierarchy of controls prioritises elimination, substitution and engineering controls over administrative measures and PPE. ALARP requires continued reduction of risk until further reduction is not reasonably practicable, with decisions supported by evidence and defensible reasoning. Controls must be implemented, verified and reviewed after change, incidents, near misses or evidence of deterioration. Competent participation, ethical reporting, management commitment and careful use of technology are essential to effective safety governance.

Key Terms

Hazard: A source or situation with potential to cause harm.

Risk: Combination of likelihood and severity of harm.

Hazardous event: An event through which a hazard may cause harm.

Consequence: The outcome produced by a hazardous event.

Exposure: Contact between a person and a hazard.

Inherent risk: Risk before additional controls.

Residual risk: Risk remaining after controls.

HIRA: Hazard identification and risk assessment.

JSA: Structured analysis of the steps and hazards of a job.

HAZID: Broad, multidisciplinary hazard identification study.

HAZOP: Systematic examination of process deviations using guidewords.

What-if analysis: Examination of hazards through structured hypothetical questions.

Risk matrix: Grid combining likelihood and consequence ratings.

Hierarchy of controls: Ordered preference for methods of reducing risk.

ALARP: As low as reasonably practicable.

Engineering control: Physical design measure that separates people from hazards.

Administrative control: Rule, procedure, training or organisational measure.

PPE: Personal protective equipment worn by a worker.

Management of change: Controlled process for assessing risks created by change.

Review Questions

Short Answer Questions

1. Define a hazard, a hazardous event and a consequence.
2. List seven major categories of industrial hazards.
3. What is the purpose of a job safety analysis?
4. State the five levels of the hierarchy of controls.
5. Why should a risk matrix not be treated as an exact probability model?

Long Answer Questions

1. Explain the stages of a complete hazard identification and risk assessment process.
2. Compare JSA, HAZID, HAZOP and what-if analysis, including suitable applications and limitations.
3. Discuss the identification and control of chemical, biological and psychosocial hazards.
4. Explain ALARP and its relationship to the hierarchy of controls.
5. Describe how management of change and control verification maintain the validity of a risk assessment.

Analytical / Application Questions

1. A maintenance worker must clean a mixer that contains electrical, pneumatic and gravitational energy. Develop a JSA, identify credible hazardous events and propose controls in hierarchy order.
2. A plant’s risk matrix assigns likelihood 3 and severity 5 to a solvent-release scenario. Explain what the score means, what additional information is needed, and why the score alone cannot justify acceptance.
3. Operators frequently bypass an interlocked guard to meet production targets. Analyse the technical and organisational causes and recommend an ALARP-based control strategy.

Multiple Choice Questions with Answers

Question 1

Which statement best defines a hazard?

A. A numerical score assigned by a risk matrix

B. A source or situation with potential to cause harm

C. The injury that follows an accident

D. A procedure used during maintenance

Correct Answer: B. A source or situation with potential to cause harm

Question 2

Which method is most specifically designed to analyse the steps of a discrete task?

A. JSA

B. HAZOP

C. HAZID

D. Trend analysis

Correct Answer: A. JSA

Question 3

In a HAZOP study, the guideword “More” is used to examine what type of deviation?

A. Complete absence of a parameter

B. Reverse direction or sequence

C. An increase beyond the design intention

D. Use of a different material only

Correct Answer: C. An increase beyond the design intention

Question 4

Which control is highest in the hierarchy of controls?

A. PPE

B. Worker training

C. Warning signage

D. Elimination

Correct Answer: D. Elimination

Question 5

If likelihood is rated 3 and severity is rated 4, what is the illustrative matrix score using R = L × S?

A. 7

B. 12

C. 16

D. 24

Correct Answer: B. 12

Question 6

Why is PPE generally considered a lower-level control?

A. It can never reduce exposure

B. It depends substantially on correct human selection, use and maintenance

C. It is always more expensive than engineering controls

D. It is prohibited in industrial workplaces

Correct Answer: B. It depends substantially on correct human selection, use and maintenance

Question 7

What does ALARP require an organisation to do?

A. Eliminate every possible risk regardless of cost or feasibility

B. Accept all risks below a matrix score of 10

C. Reduce risk until further reduction is not reasonably practicable

D. Use PPE before considering engineering controls

Correct Answer: C. Reduce risk until further reduction is not reasonably practicable

Question 8

Which situation should normally trigger a review of a risk assessment?

A. A change in equipment or process

B. A routine break taken by a worker

C. A completed training attendance sheet alone

D. A fixed office filing arrangement

Correct Answer: A. A change in equipment or process

Question 9

Which is an example of a psychosocial hazard?

A. Rotating unguarded shaft

B. Corrosive cleaning chemical

C. Excessive workload combined with low worker control

D. Poorly earthed motor casing

Correct Answer: C. Excessive workload combined with low worker control

Question 10

Why should a risk matrix score not be interpreted as an exact probability of injury?

A. Matrix ratings are usually scoring categories rather than measured probabilities

B. Severity has no relevance to risk

C. Likelihood cannot ever be assessed

D. All matrix scores have units of joules

Correct Answer: A. Matrix ratings are usually scoring categories rather than measured probabilities