What is occupational health?
Occupational health means protecting the physical, mental and social well-being of people at work. It has two big jobs:
- Improving the working environment: making the place, tools and tasks safe.
- Managing workers' health: check-ups, limits on exposure, training and support when someone is ill or injured.
It matters because adults spend about a third of their waking life at work, and work-related illness and accidents kill millions of people worldwide each year.
Five types of workplace hazards
A hazard is anything that can cause harm. Risk is how likely and how serious that harm is.
- Physical: noise, vibration, heat, cold, radiation, poor lighting.
- Chemical: dust, fumes, solvents, pesticides, asbestos.
- Biological: bacteria, viruses, moulds (health workers, farmers, waste collectors).
- Ergonomic: heavy lifting, bad posture, repeated movements, long screen time.
- Psychosocial: stress, long hours, night shifts, bullying, job insecurity.
Occupational diseases and conditions
An occupational disease is caused mainly by conditions at work. Many appear only after years of exposure.
- Pneumoconiosis (dusty lungs): silicosis from stone and sand dust (mining, quarrying, glass), asbestosis from asbestos, black lung in coal mining.
- Noise-induced hearing loss: factories, construction, airports.
- Musculoskeletal disorders: back pain, neck pain, carpal tunnel syndrome from typing.
- Skin diseases: dermatitis from cement, dyes and cleaning chemicals.
- Poisoning: lead, mercury, pesticides.
- Heat stress in outdoor workers, and burnout and depression from work stress.
Improving the working environment: the hierarchy of controls
Controls are listed from most to least effective:
- Eliminate: remove the hazard (stop using a toxic chemical).
- Substitute: use something safer (water-based paint instead of solvent paint).
- Engineering controls: isolate people from the hazard (machine guards, exhaust fans, wet cutting to reduce dust, noise enclosures).
- Administrative controls: change how people work (job rotation, shorter shifts, rest breaks, warning signs, training).
- PPE (personal protective equipment): helmets, gloves, masks, ear plugs, goggles. Useful, but the last line of defence.
Ergonomics
Ergonomics fits the job to the body: table at elbow height, screen at eye level, lift with bent knees and a straight back, take short breaks.
Industrial safety and accidents
Accidents happen when unsafe acts (rushing, skipping safety steps) meet unsafe conditions (slippery floors, broken machines). Safety studies show that for every serious injury there are many minor injuries and hundreds of near-misses, so reporting near-misses prevents big accidents.
Good practice: safety signs, emergency exits, fire drills, lock-out of machines during repair, first-aid kits and trained first-aiders. Many countries have laws that make employers responsible for a safe workplace and give workers the right to refuse dangerous work.
Workers' health management
- Health check-ups before starting a job and at regular intervals (hearing tests, lung tests, blood lead levels).
- Exposure limits: e.g. noise of 85 dB averaged over 8 hours; every +3 dB halves the safe time (88 dB → 4 h, 91 dB → 2 h).
- Working hours and rest, especially for night-shift workers.
- Mental health support and fair treatment.
- Return to work after illness with adjusted duties.
Try it: a home or school workplace check
Pick a place where someone works: a kitchen, a shop, your study desk. List one hazard of each type. Then for your top hazard, write one control from each step of the ladder. Measure your desk: is it at elbow height when you sit?
Key formulas and definitions
- Hazard = anything that can cause harm; Risk = likelihood × severity
- 5 hazards: physical, chemical, biological, ergonomic, psychosocial
- Hierarchy of controls: eliminate → substitute → engineering → administrative → PPE
- Noise limit: 85 dB for 8 h = 100% dose
- Safe time T = 8 ÷ 2^((L − 85) ÷ 3) hours
- Dose (%) = hours worked ÷ safe time × 100
Worked examples
1. A worker is exposed to 88 dB. How long can they safely work per day?
88 is 3 dB above 85, so the safe time halves once: 8 ÷ 2 = 4 hours.
2. A machine runs at 91 dB for a full 8-hour shift. What is the noise dose?
91 is 6 dB above 85, so safe time = 8 ÷ 2² = 2 h. Dose = 8 ÷ 2 × 100 = 400%. Four times the limit.
3. Ear plugs cut 15 dB from 97 dB. What is the new safe time?
97 − 15 = 82 dB. That is 3 dB below 85, so the safe time doubles: 16 hours. An 8 h shift is now a 50% dose.
4. A stone-cutting unit has a lot of dust. Suggest one control from each level.
Eliminate: buy pre-cut stone. Substitute: use a less silica-rich material. Engineering: wet cutting and exhaust fans. Admin: job rotation and dust training. PPE: proper dust masks (respirators).
Common mistakes
- Thinking PPE is the best control. It is the last line of defence; removing or blocking the hazard is better.
- Believing noise damage hurts right away. Hearing loss is slow, painless and permanent.
- Treating each +3 dB as a small change. +3 dB means double the sound energy and half the safe time.
- Ignoring stress. Psychosocial hazards like long hours and bullying are real health hazards too.