NEBOSH National General Certificate Chemical, Biological and Health Hazards Syllabus

State the hierarchy of control for exposure to hazardous substances under COSHH (general principles).

Eliminate/substitute the substance; control at source (enclosure, LEV, process change); reduce numbers exposed and exposure time (organisational); provide PPE/RPE as a last resort. Always control at source before relying on PPE.

What is Local Exhaust Ventilation (LEV) and name its five basic components.

An engineering control that captures contaminant at or near its source. Components: hood/intake, ducting, air cleaner/filter, fan (air mover), and discharge/exhaust to a safe place.

How often must an LEV system be thoroughly examined and tested under COSHH?

At least once every 14 months for most systems (more frequently for certain high-risk processes such as some blasting and grinding operations).

What is the difference between dilution ventilation and local exhaust ventilation?

Dilution (general) ventilation reduces contaminant concentration by mixing with large volumes of fresh air; suitable for low-toxicity, low-quantity contaminants. LEV captures contaminant at source before it spreads, suitable for more toxic substances.

What factors determine the selection of suitable Respiratory Protective Equipment (RPE)?

Nature/toxicity and form of the contaminant, its concentration vs WEL, oxygen level (deficient atmospheres need air-supplied), duration of work, wearer fit/facial features, and work demands. RPE must be adequate and suitable, and face-fit tested for tight-fitting types.

What is the difference between respirators and breathing apparatus?

Respirators filter contaminants from the surrounding air (rely on ambient air being breathable). Breathing apparatus supplies clean air/oxygen from an independent source and must be used in oxygen-deficient or highly toxic atmospheres (e.g. confined spaces).

Why is health surveillance carried out, and give examples of methods.

To detect early signs of work-related ill health so action can be taken, and to check control measures are effective. Methods include lung function tests (spirometry) for respiratory hazards, audiometry, skin inspection for dermatitis, and biological monitoring (urine/blood).

What is the difference between air sampling and biological monitoring?

Air (atmospheric) sampling measures the concentration of contaminant in the workplace air (the potential dose). Biological monitoring measures the substance or its metabolite in the body (blood, urine, breath), indicating the actual absorbed dose from all routes.

Describe the health effects and key control measures for asbestos.

Asbestos fibres cause asbestosis (lung fibrosis), lung cancer, and mesothelioma (cancer of the pleura). Effects are chronic with long latency. Controls: licensed removal, enclosure, wetting, HEPA filtration, RPE, and the duty to manage asbestos in non-domestic premises.

What health hazards are associated with respirable crystalline silica?

Silica dust causes silicosis (progressive lung fibrosis) and is linked to lung cancer and COPD. It arises from cutting/grinding stone, concrete and sand. Controls: water suppression, LEV, and RPE.

What are the health effects of inorganic lead exposure and which group is especially at risk?

Lead causes anaemia, abdominal pain, nervous system damage, and kidney damage; it is a reproductive toxin. Young persons and women of reproductive capacity are at particular risk, and lead is controlled under the Control of Lead at Work Regulations.

What is carbon monoxide and why is it dangerous?

$\ce{CO}$ is a colourless, odourless gas from incomplete combustion. It binds to haemoglobin forming carboxyhaemoglobin with about 200x the affinity of oxygen, reducing oxygen transport and causing headache, unconsciousness and death (a chemical asphyxiant).

Distinguish between a simple asphyxiant and a chemical asphyxiant.

A simple asphyxiant displaces oxygen from the air, reducing the available oxygen (e.g. nitrogen, carbon dioxide, methane). A chemical asphyxiant interferes with the body's uptake or use of oxygen (e.g. carbon monoxide, hydrogen cyanide).

What is occupational dermatitis and what are its two main types?

Inflammation of the skin caused by contact with substances. Irritant contact dermatitis (direct damage from irritants such as solvents/detergents) and allergic contact dermatitis (an immune sensitisation reaction, e.g. to chromium, epoxy resins).

What are the four groups of the Biological Agents hazard classification (Hazard Groups 1-4)?

Group 1: unlikely to cause human disease. Group 2: can cause disease, unlikely to spread, treatment usually available. Group 3: severe disease, may spread, treatment usually available. Group 4: severe disease, high spread risk, usually no effective treatment/prophylaxis.

Give examples of occupational exposure to biological agents and the diseases they cause.

Leptospirosis (Weil's disease) from rat urine (sewer/farm workers); legionella in water systems causing Legionnaires' disease; hepatitis B/C and HIV from blood (healthcare/needlestick); anthrax from animal hides; tetanus from soil-contaminated wounds.

What conditions favour the growth of Legionella bacteria, and how is exposure controlled?

Legionella thrives in water between $20$ and $45\,^{\circ}\mathrm{C}$, with stagnation, sludge/scale and nutrients. Control: keep hot water above $60\,^{\circ}\mathrm{C}$ and cold below $20\,^{\circ}\mathrm{C}$, avoid stagnation/dead legs, clean and disinfect systems, and maintain cooling towers.

What general precautions reduce the risk from biological agents?

Vaccination/immunisation, good personal hygiene and handwashing, prohibition of eating/drinking in contaminated areas, PPE (gloves, eye protection), safe disposal of clinical/sharps waste, vermin and water-system control, and prompt wound treatment.

What principles apply to the safe storage of hazardous substances?

Store in suitable labelled containers, segregate incompatible substances (e.g. oxidisers from flammables, acids from alkalis), provide bunding/secondary containment for liquids, ventilation, secure access, limit quantities, and keep an inventory with SDS available.

Why must oxidising agents and flammable substances be stored separately?

Oxidising agents provide oxygen that can intensify a fire or cause spontaneous ignition of flammables, dramatically increasing fire and explosion risk if they are mixed or stored together.

What methods are used for the safe disposal of hazardous waste?

Specialist licensed waste contractors, incineration, chemical neutralisation/treatment, encapsulation, and licensed landfill for permitted wastes. Waste must be classified, segregated, stored safely, and tracked using duty-of-care transfer/consignment documentation.

What are the most common types of work-related ill health in the UK?

Musculoskeletal disorders (MSDs), work-related stress/anxiety/depression, occupational dermatitis, occupational asthma, noise-induced hearing loss, hand-arm vibration syndrome, and occupational cancers (the most common cause of work-related deaths).

What is occupational asthma and name common causative agents (respiratory sensitisers).

A reversible narrowing of the airways triggered by workplace sensitisers. Common agents: isocyanates (paint spraying), flour/grain dust, wood dust, solder flux (colophony), latex, and laboratory animal proteins.

Define a 'sensitiser'.

A substance that, after initial exposure(s), causes the body's immune system to react, so that subsequent exposures even at very low levels provoke an allergic response (respiratory sensitiser causing asthma, or skin sensitiser causing allergic dermatitis).

What is work-related stress (HSE definition)?

The adverse reaction people have to excessive pressures or other types of demand placed on them at work. Stress is not an illness but sustained stress can lead to mental and physical ill health.

List the six HSE Management Standards for work-related stress.

Demands, Control, Support, Relationships, Role, and Change. These cover the primary sources of stress at work that, if not managed, are associated with poor health, lower productivity and increased sickness absence.

What are typical causes and effects of work-related stress?

Causes: high demands/workload, lack of control, poor support, bullying/poor relationships, role ambiguity, and poorly managed change. Effects: anxiety, depression, fatigue, raised blood pressure, increased absence, errors, reduced performance, and higher accident rates.

What is workplace violence (HSE definition) and how can the risk be controlled?

Any incident in which a person is abused, threatened or assaulted in circumstances relating to their work. Controls: risk assessment, environment/zoning and screens, cash handling procedures, lone-worker systems, conflict-management training, CCTV/alarms, and incident reporting.

What signs may indicate an employee has an alcohol or drug problem, and how should employers manage it?

Signs: lateness/absenteeism, mood swings, reduced performance, poor coordination, and increased errors/accidents. Management: a clear written policy, awareness training, confidential support/referral, drug-and-alcohol testing where justified, and disciplinary procedures for safety-critical breaches.

What is meant by 'promoting health and wellbeing' at work and why is it beneficial?

Proactive employer initiatives beyond legal minimums to improve workers' physical and mental health, e.g. health screening, smoking cessation, exercise schemes, healthy eating, mental-health support, and flexible working. Benefits: reduced absence/turnover, higher morale and productivity, and a better reputation.