Occupational Health, Hygiene and Worker Well-being

Introduction and context

Construction work exposes people to hazards that may cause immediate injury, occupational disease, reduced work capacity, or long-term effects on physical and psychological well-being. Unlike many safety events, occupational illnesses often develop gradually. A worker may therefore remain unaware of exposure until disease has become irreversible. Effective construction safety management must consequently address both acute hazards and cumulative exposures.

Occupational health concerns the prevention, recognition and management of work-related illness and impairment. Occupational hygiene is the discipline of anticipating, recognising, evaluating and controlling workplace health hazards. Worker well-being is broader: it includes physical health, psychological health, social functioning, dignity, recovery and the worker’s capacity to perform safely and sustainably.

Construction projects present particular difficulties. Workplaces change daily; several employers share one site; subcontractors may use different procedures; environmental conditions vary; and exposure can occur during short, high-intensity tasks such as cutting concrete, abrasive blasting, demolition or confined-space entry. A competent system therefore combines engineering, medical, organisational and behavioural controls rather than relying on personal protective equipment alone.

Learning objectives

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

1. Explain the principles of occupational health, hygiene and worker well-being.

2. Identify major construction exposures, including dust, silica, asbestos, noise, vibration, chemicals, heat and biological agents.

3. Evaluate exposure using qualitative and quantitative methods, while recognising uncertainty and limitations.

4. Apply the hierarchy of controls to design practical risk-reduction measures.

5. Assess ergonomic demands, fatigue, stress and mental-health risks.

6. Develop an integrated occupational-health management programme for a construction project.

7. Critically evaluate ethical, regulatory, technological and managerial issues in worker protection.

1. Foundations of occupational health and hygiene

1.1 Hazard, exposure, dose and risk

A hazard is an inherent property or situation with potential to cause harm. Exposure occurs when a worker comes into contact with the hazard. Dose is the amount reaching the relevant body system over a defined period. Risk is the combination of the likelihood and severity of harm under specified conditions.

The distinction is important. Respirable crystalline silica is hazardous, but disease risk depends on factors such as airborne concentration, duration, particle size, effectiveness of respiratory protection and individual susceptibility. A hazard assessment asks what can cause harm; an exposure assessment asks who is exposed, by what route, how much and for how long.

Exposure routes include inhalation, skin absorption, ingestion, injection and contact with the eyes. Construction risk assessments should consider normal work, maintenance, cleaning, breakdowns, emergency operations and foreseeable misuse.

1.2 Occupational hygiene cycle

A professional hygiene programme follows a continuous cycle:

• Anticipation: identify hazards before work begins, using design information, product data, task analysis and experience from similar projects.
• Recognition: determine the agents, sources, routes and exposed groups.
• Evaluation: measure or estimate exposure and compare results with applicable occupational exposure limits or other authoritative criteria.
• Control: apply the hierarchy of controls and verify performance.
• Review: reassess after changes in materials, equipment, methods, weather, staffing or health evidence.

This is not a one-time inspection. Exposure may change when a saw is moved indoors, when a ventilation system becomes blocked, or when production rates increase.

1.3 Exposure limits and uncertainty

Occupational exposure limits may include an eight-hour time-weighted average, a short-term exposure limit and a ceiling value. They are legal limits in some jurisdictions and advisory criteria in others. They should not be interpreted as a boundary between safe and unsafe: susceptible workers may be harmed below a limit, and some carcinogens have no demonstrably safe threshold.

For a contaminant with concentration varying during a shift, an illustrative time-weighted average is:

\[

C_{TWA}=\frac{\sum_{i=1}^{n} C_i t_i}{\sum_{i=1}^{n}t_i}

\]

where \(C_i\) is concentration during period \(i\), \(t_i\) is the duration of that period, and all concentrations and times must use consistent units. This calculation assumes the samples represent the worker’s relevant exposure periods and that concentration is reasonably characterised within each period. It does not by itself assess short-term peaks, skin exposure or combined toxicological effects.

For agents with additive effects, a screening approach sometimes used is:

\[

I=\sum_{i=1}^{n}\frac{C_i}{L_i}

\]

where \(C_i\) is the measured concentration of substance \(i\), and \(L_i\) is its corresponding exposure limit. An index greater than 1 suggests that the combined exposure may exceed the criterion, but this approach is valid only when substances have sufficiently similar toxicological effects and the limits are comparable. It must not replace professional toxicological judgement.

Sampling strategy is as important as arithmetic. Personal sampling generally represents the worker better than fixed-area sampling, while task-based sampling identifies high-exposure operations. Results require quality assurance, calibrated instruments, documented sampling times and competent interpretation.

2. Principal construction health hazards

2.1 Dust and respirable crystalline silica

Construction dust may contain nuisance particles, cement, wood dust, metals, mineral fibres and respirable crystalline silica. The finest particles can penetrate deep into the lungs. Respirable silica is associated with silicosis, chronic obstructive pulmonary disease, lung cancer and kidney disease. Risk is especially significant during concrete cutting, drilling, grinding, crushing, tunnelling, masonry work and demolition.

The preferred controls are:

• eliminate or substitute high-dust methods, such as using prefabricated components or off-site cutting;
• use wet cutting and on-tool water suppression;
• use local exhaust ventilation with suitable filtration;
• enclose processes and isolate nearby workers;
• schedule dusty work when fewer people are present;
• maintain equipment and prevent compressed-air blow-down;
• use suitable respiratory protective equipment within a complete respiratory protection programme.

Water suppression must be properly designed: insufficient flow may not control dust, while excessive water can create electrical, slip and contamination hazards. Vacuum systems must be designed for fine dust, inspected and fitted with appropriate filters. Respirators require selection, fit testing, maintenance, clean-shaven sealing surfaces where relevant, and worker training.

2.2 Asbestos

Asbestos fibres can cause asbestosis, lung cancer and mesothelioma, often after long latency periods. It may occur in older insulation, roofing, boards, floor materials, sprayed coatings, cement products and pipework. The critical management principle is that suspect material must not be disturbed until its status is determined by a competent person.

Before refurbishment or demolition, an asbestos survey should identify material, condition, accessibility and likely disturbance. Work involving asbestos should be planned under applicable law by trained and authorised personnel. Controls may include isolation, controlled removal, negative-pressure enclosures where required, wet methods, specialised vacuuming, decontamination and licensed waste disposal. Ordinary construction dust masks are not an adequate asbestos-control programme. Deliberate concealment of asbestos findings is both an ethical and potentially criminal failure because it transfers invisible risk to workers and building occupants.

2.3 Noise

Noise can cause permanent hearing loss, tinnitus, interference with communication and increased accident risk. Common sources include breakers, piling, compressors, generators, saws and heavy vehicles.

Noise management begins with quieter procurement and engineering controls: low-noise equipment, isolation, enclosure, damping, maintenance and distance. Administrative measures include limiting time near sources, zoning and scheduling. Hearing protection is important but should not substitute for feasible source control. Hearing conservation programmes should include baseline and periodic audiometry, training, equipment selection and investigation of threshold shifts.

Noise measurements must account for instrument calibration, exchange-rate conventions and the specific regulatory criterion. A sound level expressed in decibels is logarithmic; it should not be averaged as though it were an ordinary linear quantity. Noise control also requires preservation of alarms and communication, particularly where hearing protection or enclosure could reduce situational awareness.

2.4 Hand-arm and whole-body vibration

Hand-arm vibration from grinders, breakers and vibrating tools can cause vascular, neurological and musculoskeletal disorders. Whole-body vibration from vehicles and mobile plant may contribute to back pain and fatigue, particularly on uneven surfaces and during prolonged operation.

Controls include low-vibration equipment, task redesign, preventive maintenance, balanced tools, reduced trigger time, job rotation where it genuinely reduces dose, improved seating and suspension, smooth haul roads and operator training. Gloves may protect against cold and sharp edges but are not a universal solution to hand-arm vibration. Exposure should be assessed using appropriate vibration magnitude, direction and duration data; “hours using the tool” alone may be misleading.

2.5 Chemicals

Construction chemicals include solvents, curing compounds, epoxies, isocyanates, fuels, welding fumes, paints, acids, alkalis and admixtures. Health effects range from irritation and sensitisation to neurological, reproductive, respiratory and carcinogenic effects.

A chemical management system should include an inventory, current safety data sheets, container labelling, compatibility review, storage controls, ventilation, spill response, exposure monitoring where indicated and health surveillance for relevant hazards. Safety data sheets are essential but not sufficient: they may not describe the actual site process, mixture, temperature or combined exposure.

Substitution is often effective—for example, selecting water-based or low-volatility products where performance permits. Local exhaust ventilation should capture contaminants close to the source, whereas general dilution ventilation may be inadequate for highly toxic or rapidly generated contaminants. Workers must understand that odour is not a reliable indicator of safety.

2.6 Heat, cold and solar exposure

Heat stress occurs when metabolic heat, environmental heat and clothing exceed the body’s ability to dissipate heat. Risk is increased by humidity, radiant heat, direct sun, heavy protective clothing, dehydration, acclimatisation status, illness and certain medicines. Heat illness may progress from cramps and exhaustion to life-threatening heat stroke.

A heat programme should provide cool drinking water, shaded or cooled recovery areas, acclimatisation for new or returning workers, work-rest planning, attention to weather forecasts, buddy monitoring and emergency arrangements. Work-rest schedules should be based on environmental measurements and workload rather than a fixed universal rule. A confused, collapsing or very hot worker requires urgent medical response; suspected heat stroke is an emergency, not a disciplinary issue.

Cold, wind, wet clothing and reduced dexterity can also cause illness and accidents. Layered clothing, dry shelters, heated rest areas, appropriate gloves and task planning are required. Solar ultraviolet exposure should be managed through shade, scheduling, protective clothing, eye protection and skin protection.

2.7 Biological agents

Workers may encounter bacteria, viruses, fungi, parasites, mould, contaminated water, sewage, animal waste, insects and vectors. Risks arise during excavation, wastewater work, healthcare-facility construction, demolition of water-damaged buildings, waste handling and work in areas with infectious disease.

Controls include hazard information, sanitation, safe water, hand hygiene, vaccination where indicated, sharps controls, pest management, ventilation, appropriate gloves and respiratory protection, and procedures for exposure incidents. Biological risk assessments must consider the local epidemiological context and changing public-health conditions. PPE is particularly important but must be removed and disposed of without contaminating the worker or work environment.

3. Ergonomics and physical demands

Construction tasks commonly involve lifting, carrying, pushing, pulling, kneeling, overhead work, repetitive hand movements, awkward postures and sustained equipment operation. Musculoskeletal disorders arise from the interaction of force, posture, repetition, duration, vibration, psychosocial stress and inadequate recovery.

Ergonomic assessment should analyse the complete task rather than the object weight alone. Useful interventions include:

• designing out manual handling through prefabrication, mechanical lifting and material delivery at point of use;
• reducing load size and carrying distance;
• adjustable work platforms and tools;
• improved handles and balanced equipment;
• redesign of repetitive tasks;
• team lifting only when risks and communication are controlled;
• micro-pauses and recovery periods;
• worker participation in trialling solutions.

A “lift with the legs” instruction cannot compensate for an intrinsically excessive or awkward lift. Manual-handling limits, where used, are screening tools rather than guarantees of safety; individual capability and task geometry remain decisive.

4. Fatigue, stress and mental health

4.1 Fatigue as an organisational risk

Fatigue reduces vigilance, reaction time, judgement, memory and motor coordination. It may result from long shifts, night work, insufficient sleep, commuting, heat, physically demanding tasks, illness, medication or emotional distress. Fatigue is therefore not simply a worker’s personal failure.

A fatigue-risk management system should address roster design, maximum hours, overtime approval, night work, rest opportunities, travel after shifts, task criticality and reporting. High-risk activities—crane operations, traffic control, isolation work and work at height—should not be assigned to severely fatigued personnel. Supervisors should use non-punitive fitness-for-work processes and provide alternatives to unsafe driving or working.

4.2 Psychosocial hazards

Psychosocial hazards include excessive workload, low control, bullying, harassment, violence, insecure employment, poor consultation, role ambiguity, unfair treatment, isolation and conflict between production and safety demands. They can produce anxiety, depression, burnout, sleep disturbance, substance misuse and increased injury likelihood.

A psychologically healthy workplace combines prevention and support. Prevention requires realistic programmes, adequate staffing, respectful supervision, worker voice, fair procedures, anti-harassment controls and competent change management. Support includes confidential assistance, access to occupational health or counselling, crisis pathways, reasonable adjustments and return-to-work planning. Mental-health initiatives should not be reduced to resilience training while harmful work organisation remains unchanged.

Leaders influence well-being through what they reward. If supervisors praise unsafe speed and punish reporting, formal policies have little practical effect. Consultation must be meaningful: workers should help identify hazards, evaluate controls and review whether interventions work.

5. Applying the hierarchy of controls

The hierarchy of controls ranks interventions generally from most to least reliable:

1. Elimination: remove the hazardous task or material.

2. Substitution: replace it with a less hazardous alternative.

3. Engineering controls: isolate people from the hazard or control it at source.

4. Administrative controls: change scheduling, procedures, training or supervision.

5. Personal protective equipment: place a barrier on the worker.

The hierarchy is a decision framework, not a rigid rule that permits lower-level controls to be ignored. Effective programmes normally combine levels. For example, silica risk may be reduced by prefabrication, wet cutting, exclusion zones, exposure scheduling, housekeeping, respirators and health surveillance. PPE is essential where residual risk remains, but it is vulnerable to poor fit, misuse, discomfort, contamination and inconsistent wearing.

A control should be evaluated for effectiveness, reliability, maintainability, compatibility with production, unintended consequences and equity. A ventilation system that removes dust but creates excessive noise or heat may simply exchange one hazard for another.

6. Health surveillance and occupational-health services

Health surveillance is the systematic collection and interpretation of health information for workers exposed to specified hazards. It may include questionnaires, clinical assessment, lung-function testing, audiometry, biological monitoring or skin examination, depending on the hazard and legal requirements. It is not a substitute for exposure control.

A sound programme has a defined purpose, competent providers, informed consent, confidentiality, baseline information where appropriate, timely feedback and procedures for responding to abnormal findings. Employers generally need information about fitness, restrictions or trends—not unrestricted access to personal medical details. Medical information must be protected from discrimination and unauthorised disclosure.

Biological monitoring measures a substance or metabolite in biological media such as urine or blood. It can incorporate all routes of exposure but may be affected by metabolism, timing, background exposure and individual variability. It should be interpreted by qualified professionals and never used to excuse poor environmental controls.

7. Integrated management on a construction project

Occupational health should be incorporated into project planning, procurement and design. A practical project system includes:

• a health-risk register linked to the construction programme;
• competence requirements for occupational hygienists, asbestos professionals and health providers;
• pre-construction surveys and hazardous-material registers;
• method statements addressing exposure pathways and controls;
• contractor and subcontractor coordination;
• baseline and task-based exposure assessments;
• inspection, maintenance and calibration arrangements;
• worker induction, toolbox communication and multilingual information;
• incident, symptom and near-miss reporting;
• health surveillance where justified;
• emergency response for chemical release, heat illness and biological exposure;
• periodic management review using leading and lagging indicators.

Leading indicators may include completed exposure assessments, functioning ventilation systems, fit-test completion, corrective-action closure and worker participation. Lagging indicators include occupational disease, hearing shifts, dermatitis, heat illness and absence patterns. Indicators must be interpreted cautiously: a low reported illness rate may reflect under-reporting rather than good health.

8. Worked application: personal silica exposure

During a shift, a worker spends 2 hours cutting concrete at an estimated personal concentration of 0.40 mg/m³, 3 hours installing materials at 0.02 mg/m³, and 3 hours performing office-related site administration at 0.005 mg/m³. Assuming these concentrations represent the worker’s inhalation exposure and using an eight-hour averaging period:

\[

C_{TWA}=\frac{(0.40)(2)+(0.02)(3)+(0.005)(3)}{8}

\]

\[

C_{TWA}=\frac{0.80+0.06+0.015}{8}=0.109375\text{ mg/m}^3

\]

Thus, the estimated eight-hour TWA is approximately 0.109 mg/m³. This result must not be interpreted without the applicable jurisdictional limit, sampling quality, task peaks and control context. If cutting produces short-term peaks, an eight-hour average may conceal important exposure. The appropriate response is to improve source control and obtain representative personal sampling, not merely to compare the number with a limit.

9. Illustrative case study: refurbishment of an occupied hospital

Background

A contractor was appointed to refurbish an older hospital wing while adjacent clinical services continued. The project involved drilling masonry, removing old floor tiles, applying epoxy coatings and replacing ventilation ductwork. Workers included direct employees, several subcontractors and hospital maintenance personnel.

Problem

A pre-start review identified possible asbestos-containing materials, silica-generating drilling, solvent vapours, noise, infection-control concerns and high schedule pressure. The initial plan relied mainly on disposable respirators and short toolbox talks. Hospital staff reported odour and dust migration into a clinical corridor.

Analysis

The project team mapped tasks, materials, adjacent occupants and airflow. A competent asbestos survey found suspect insulation and floor adhesive requiring controlled management. Personal sampling showed that uncontrolled dry drilling generated substantially higher respirable dust than wet drilling with local extraction. The project also had weak segregation between construction and clinical areas. Workers reported fatigue caused by extended evening shifts.

Approach and solution

The client required the contractor to revise the plan. Asbestos materials were isolated and removed by an authorised specialist before general work. Drilling was changed to wet methods with on-tool extraction; temporary barriers and negative pressure were installed where appropriate, with airflow verification. Low-emission coatings replaced a solvent-rich product. Noisy work was scheduled away from clinical procedures, and equipment was maintained and enclosed where feasible.

A permit and interface system coordinated the contractor, hospital infection-control team and maintenance department. Personal sampling, surface checks and air monitoring were used according to task risk. Workers received fit testing, decontamination instruction and information in relevant languages. Evening shifts were shortened, recovery periods were introduced and supervisors were authorised to stop work when controls failed.

Outcome

Dust migration complaints ceased, asbestos was managed before disturbance, and exposure results under controlled conditions were substantially lower than during the initial trial. The project experienced a short programme delay but avoided a potentially serious occupational and public-health event. Worker reporting increased after management introduced non-punitive stop-work authority.

Learning points

The case demonstrates that occupational health is an interface-management issue, not merely a PPE issue. Early surveys, design changes, competent specialists, monitoring, worker participation and protection of third parties were mutually reinforcing. It also illustrates that production pressure can be managed more effectively when health requirements are built into procurement and scheduling rather than added after work begins.

10. Governance, ethics and contemporary developments

Employers have a duty to provide reasonably safe work, competent supervision, information, consultation and suitable controls, subject to the applicable national legal framework. Contractors must coordinate with clients and other employers, while clients and designers have influence over material selection, access, sequencing and constructability.

Ethical practice requires precaution where evidence of harm is serious, respect for worker dignity, truthful communication of uncertainty, equitable protection of migrant and temporary workers, and prohibition of retaliation for reporting symptoms or hazards. Productivity targets must never make concealment of exposure the rational choice.

Digital technologies can support, but not replace, professional judgement. Wearable heat sensors, connected noise dosimeters, environmental monitors, digital permits, BIM-based hazard registers and remote inspections can improve visibility. Artificial intelligence may identify patterns in exposure data, predict high-risk tasks or help prioritise inspections. However, algorithms can produce false alarms, encode biased historical data, expose personal information and encourage surveillance. Data governance should specify purpose, access, retention, validation and worker rights. AI should support competent decision-makers, not determine fitness for work or disciplinary action without human review.

Contemporary best practice is moving toward prevention by design, safer materials, prefabrication, climate-resilient work planning, integrated mental-health management and continuous worker participation. Climate change increases heat, wildfire smoke, flooding, vector-borne disease and emergency-response demands, making occupational health an increasingly important element of project resilience.

Challenges and limitations

Occupational-health management faces incomplete exposure data, transient labour, subcontracting, changing work fronts, variable compliance, limited specialist availability and long disease latency. Exposure limits differ between jurisdictions and may lag scientific evidence. Sampling captures only selected times and workers; a result cannot automatically represent every task. Health surveillance may identify harm without revealing its workplace source. Behavioural programmes may fail if design and procurement decisions create unavoidable exposure. Finally, apparent success can be misleading when workers fear reporting or when illness appears years after project completion.

These limitations support a precautionary and learning-oriented approach: use multiple information sources, document assumptions, involve workers, verify controls under realistic conditions and revise decisions when evidence changes.

Chapter Summary

Occupational health, hygiene and worker well-being are essential components of construction safety management. Health protection begins by distinguishing hazards from exposure, dose and risk, and by applying the occupational-hygiene cycle of anticipation, recognition, evaluation, control and review. Major construction hazards include respirable dust and silica, asbestos, noise, vibration, chemicals, heat, cold, biological agents and ergonomic demands.

The hierarchy of controls prioritises elimination, substitution and engineering controls over administrative measures and PPE. Effective programmes require competent assessment, representative monitoring, reliable maintenance, health surveillance where justified, emergency preparedness and worker participation. Fatigue, psychosocial hazards and mental health must be managed through work organisation and respectful leadership, not merely individual coping programmes. Ethical governance requires confidentiality, non-discrimination, truthful communication and protection of workers who report concerns. Digital tools and AI can improve monitoring and decision-making, but require validation, privacy controls and human oversight.

Key Terms

Hazard: An inherent property or situation capable of causing harm.

Exposure: Contact between a person and a hazardous agent or condition.

Dose: The amount of an agent reaching a body system over a specified period.

Risk: The likelihood and severity of harm under defined conditions.

Occupational hygiene: Anticipation, recognition, evaluation and control of workplace health hazards.

Respirable dust: Fine airborne particles capable of penetrating to the gas-exchange region of the lungs.

Crystalline silica: A mineral component of many construction materials associated with silicosis and other diseases.

Asbestos: A group of fibrous minerals associated with asbestosis, lung cancer and mesothelioma.

Time-weighted average: An exposure average calculated over a specified period, commonly a work shift.

Short-term exposure limit: A criterion intended to control exposure over a brief period.

Hierarchy of controls: A ranking of hazard-control methods from elimination to PPE.

Local exhaust ventilation: Ventilation that captures contaminants near their source.

Health surveillance: Systematic collection and interpretation of work-related health information.

Biological monitoring: Measurement of a substance or metabolite in a biological sample.

Ergonomics: Design of work to fit human capabilities and limitations.

Fatigue: Reduced mental or physical performance caused by insufficient recovery or excessive demand.

Psychosocial hazard: A work-design or social condition with potential to harm psychological or physical health.

Worker well-being: Physical, psychological and social health and the capacity to function safely and sustainably.

Exposure limit: A regulatory or advisory criterion used to guide control of workplace exposure.

Review Questions

Short Answer Questions

1. Distinguish between a hazard, exposure, dose and risk.

2. State the four stages of the occupational-hygiene cycle.

3. Why is PPE considered a lower-level control than elimination or engineering control?

4. Identify three health effects associated with respirable crystalline silica.

5. Give four organisational causes of fatigue on construction projects.

Long Answer Questions

1. Explain how a construction project should manage asbestos risk from pre-construction survey through disposal.

2. Discuss the hierarchy of controls for concrete cutting and evaluate the limitations of relying on respirators.

3. Describe an integrated programme for managing construction noise and vibration.

4. Explain how psychosocial hazards and work organisation influence mental health and safety performance.

5. Critically discuss the role, benefits and limitations of health surveillance.

Analytical / Application Questions

1. A worker spends 1 hour at 0.30 mg/m³, 2 hours at 0.08 mg/m³ and 5 hours at 0.01 mg/m³ of a contaminant. Calculate the eight-hour TWA and explain why the result alone may be insufficient for control decisions.

2. Develop a control plan for a demolition task involving suspected asbestos, silica dust, high noise and occupied neighbouring premises. Justify the order of your controls.

3. A project has increasing overtime, heat alerts, minor vehicle incidents and complaints of poor sleep. Analyse the likely interacting causes and propose a fatigue-risk management intervention.

Multiple Choice Questions with Answers

Question 1

Which activity is the first stage of the occupational-hygiene cycle?

A. Anticipation

B. Exposure monitoring

C. Medical treatment

D. PPE inspection

Correct Answer: A. Anticipation

Question 2

Which control most directly captures dust at the point where it is generated?

A. Worker rotation

B. Local exhaust ventilation

C. General safety induction

D. Disposable gloves

Correct Answer: B. Local exhaust ventilation

Question 3

What disease is strongly associated with respirable crystalline silica exposure?

A. Silicosis

B. Colour blindness

C. Malaria

D. Hearing loss

Correct Answer: A. Silicosis

Question 4

Why must suspect asbestos-containing material not be disturbed before assessment?

A. It always causes immediate poisoning

B. Disturbance can release hazardous fibres

C. It makes concrete structurally stronger

D. It prevents noise monitoring

Correct Answer: B. Disturbance can release hazardous fibres

Question 5

Which statement about a time-weighted average is correct?

A. It uses concentration and duration consistently across exposure periods

B. It measures only the highest instantaneous concentration

C. It applies only to noise measurements

D. It eliminates the need for representative sampling

Correct Answer: A. It uses concentration and duration consistently across exposure periods

Question 6

Which is an example of substitution?

A. Providing a respirator

B. Scheduling work at night

C. Replacing a solvent-rich coating with a less hazardous product

D. Posting a warning sign

Correct Answer: C. Replacing a solvent-rich coating with a less hazardous product

Question 7

Which condition increases the likelihood of heat stress?

A. Adequate acclimatisation and shaded recovery

B. High humidity combined with heavy protective clothing

C. Short work duration in cool weather

D. Ready access to drinking water

Correct Answer: B. High humidity combined with heavy protective clothing

Question 8

What is a limitation of job rotation as a vibration control?

A. It may fail if the total exposure dose is not actually reduced

B. It always increases vibration magnitude

C. It eliminates the need for equipment maintenance

D. It is an engineering control

Correct Answer: A. It may fail if the total exposure dose is not actually reduced

Question 9

Which is a psychosocial hazard?

A. Uncontrolled solvent vapour

B. Excessive workload and low worker control

C. Respirable silica

D. Ultraviolet radiation

Correct Answer: B. Excessive workload and low worker control

Question 10

What is an essential ethical safeguard when using AI-based worker health data?

A. Allow unrestricted managerial access

B. Use it for automatic dismissal

C. Define purpose, access and privacy protections

D. Ignore false alarms

Correct Answer: C. Define purpose, access and privacy protections