The difference between hazard and risk is potential versus likelihood. A hazard is anything with the potential to cause harm, such as a wet floor, a chemical or a heavy load. A risk is how likely it is that someone will actually be harmed by that hazard, combined with how serious the harm could be. You cannot always remove the hazard, but you can usually reduce the risk.
Hazard and risk are the two words every risk assessment is built on, yet the difference between hazard and risk gets blurred all the time. This guide gives plain definitions, worked examples from real workplaces, the main types of hazard, and how risk is rated so you can decide what to deal with first.
What is a hazard?
A hazard is something that may cause harm. HSE’s guidance on managing risk tells employers to think about what may cause harm, and says plainly that “these are called hazards”.
A hazard can be an object (a ladder), a substance (bleach), a source of energy (electricity, noise), an activity (lifting), a condition (an icy car park) or the way work is organised (an impossible workload). The hazard exists whether or not anyone is near it.
What is a risk?
A risk is the chance that someone is harmed by a hazard, together with how badly. HSE describes assessing the level of risk as deciding “how likely it is that someone could be harmed and how serious it could be”.
So risk always has two parts:
- Likelihood: how probable it is that harm happens
- Severity: how bad the outcome would be if it did
Risk also depends on exposure. A tub of corrosive cleaner locked in a store that nobody visits is the same hazard as one left open on a kitchen worktop, but the risk is very different.
The difference between hazard and risk
The hazard is the thing that can hurt you. The risk is the likelihood and severity of it actually hurting someone. One describes potential, the other describes probability and consequence.
A simple way to remember it: you identify hazards, but you assess and control risks. That distinction matters because a workplace can be full of hazards and still be low risk if those hazards are well controlled. It also works the other way. A single, ordinary-looking hazard can be high risk if lots of people are exposed to it every day without controls.
Hazard and risk examples
The table shows common workplace hazards, the risk each creates, and a typical way the risk is reduced.
| Hazard | Risk | Example of reducing the risk |
|---|---|---|
| Wet floor in a corridor | Someone slips and is injured, most likely a bruise or sprain, sometimes a fracture | Fix the leak, clean up spills promptly, close the area while it dries |
| Ladder | A worker falls while reaching, with potential for serious injury | Use a mobile tower or podium step for longer jobs; check the ladder before use |
| Electricity | Shock or burns from damaged cables or equipment | Inspect equipment, remove damaged items from use, isolate before maintenance |
| Cleaning chemicals | Skin burns, eye damage or breathing in fumes | Substitute a less harmful product, dilute correctly, provide gloves and eye protection |
| Loud machinery | Permanent hearing damage over time | Quieter equipment, enclosures, limiting time in noisy areas, hearing protection |
| Heavy boxes | Back injury from repeated lifting | Reduce box weight, use trolleys, train staff in safe handling |
| Forklift trucks | A pedestrian is struck, often with serious or fatal results | Separate vehicle and pedestrian routes, trained operators, banksman where needed |
| Excessive workload | Work-related stress, anxiety and absence | Realistic targets, workload reviews, support from managers |
Notice that the hazard column never changes much from site to site. The risk column changes a great deal depending on who is exposed, how often and what controls are already in place. That is why a risk assessment has to look at your workplace, not a generic list.
Types of hazard
Hazards are usually grouped into five broad types. The labels are a convenience rather than a legal list, but they help make sure nothing is missed.
- Physical: slips and trips, work at height, moving machinery, vehicles, noise, vibration, electricity, extreme temperatures and radiation.
- Chemical: substances that can harm through contact, inhalation or ingestion, including dusts, fumes, solvents and cleaning products. These are controlled under the COSHH Regulations.
- Biological: bacteria, viruses and other micro-organisms, such as Legionella in water systems or infections in healthcare settings.
- Ergonomic: manual handling, repetitive tasks, awkward postures and poorly set-up workstations that cause musculoskeletal disorders.
- Psychosocial: aspects of work that affect mental health, including workload, lack of control, poor support, conflict and badly managed change. HSE’s Management Standards for work-related stress cover six areas: demands, control, support, relationships, role and change. Our guide to stress at work covers these in detail.
HSE’s own list of common workplace risks includes asbestos, confined spaces, display screen equipment, electrical safety, machinery, fire, gas, harmful substances, manual handling, noise, pressure equipment, slips and trips, vibration, working at height, workplace transport and work-related stress.
How is risk rated?
Risk is usually rated by combining likelihood and severity. Many organisations use a simple matrix, scoring each from 1 to 5 and multiplying them, so a score of 1 is very low and 25 is very high.
| Score | Likelihood | Severity |
|---|---|---|
| 1 | Very unlikely | Minor, no first aid needed |
| 2 | Unlikely | First aid injury |
| 3 | Possible | Injury causing time off work |
| 4 | Likely | Major injury or serious ill health |
| 5 | Very likely or almost certain | Fatality or permanent disability |
Illustrative scale. The wording and bands vary between organisations.
The law does not require a matrix or any particular scoring system. What it requires is that you judge the level of risk sensibly and do what is reasonably practicable to control it. HSE explains reasonably practicable as balancing the level of risk against the measures needed to control it in terms of money, time or trouble. A matrix is just a consistent way of showing your reasoning and deciding what to tackle first.
Two scores are worth recording for each hazard: the risk before controls and the residual risk once your controls are in place. If the residual risk is still high, you need better controls, and the hierarchy of control tells you where to look first.
How hazard and risk feed into a risk assessment
A risk assessment is the process of finding the hazards, deciding who could be harmed and how, evaluating the risk and putting sensible controls in place. Under the Management of Health and Safety at Work Regulations 1999, every employer must assess risk, and if you employ five or more people you must record the significant findings.
We cover the full process step by step in our 5 steps to risk assessment guide, the bigger picture in risk assessments: a UK guide, and our risk assessment template gives you a format to work from.
Common mistakes with hazard and risk
- Listing hazards and stopping there. A list of hazards is not a risk assessment. Each one needs a judgement about likelihood, severity and who is exposed.
- Recording risks as hazards. “Falling off a ladder” is a risk. The hazard is the ladder, or working at height.
- Ignoring health hazards. Injuries are obvious; noise, dust and stress cause harm slowly and are easy to miss.
- Forgetting non-routine work. HSE specifically points to maintenance, cleaning and changes in production as times when hazards appear.
- Never revisiting the rating. Risk changes when people, equipment or processes change, or after an accident or near miss.
Frequently asked questions
What is the difference between a hazard and a risk?
A hazard is anything with the potential to cause harm. A risk is the likelihood that someone will be harmed by that hazard, combined with how serious the harm could be. You identify hazards; you assess and control risks.
Is a wet floor a hazard or a risk?
The wet floor is the hazard. The risk is the chance of someone slipping on it and how badly they could be hurt, which depends on how many people walk that way and what controls are in place.
What are the 5 types of hazard?
Hazards are commonly grouped as physical, chemical, biological, ergonomic and psychosocial. The grouping is a practical aid to make sure nothing is missed rather than a legal definition.
How do you calculate risk?
Risk is usually rated by multiplying a likelihood score by a severity score, often on a 1 to 5 scale for each. The law does not require a particular method, only a sensible judgement of the level of risk and reasonably practicable controls.
Can you remove all risk?
Rarely. The legal duty is to reduce risk so far as is reasonably practicable, which means balancing the level of risk against the money, time and trouble needed to control it.
Is stress a hazard?
Work-related stress is a recognised workplace risk, and the hazards that cause it include excessive demands, lack of control, poor support, conflict, unclear roles and badly managed change. These are the six areas in HSE’s Management Standards.
What is residual risk?
Residual risk is the risk that remains after your control measures are in place. If it is still too high, you need to add or improve controls, starting at the top of the hierarchy of control.
Where to learn more
- Risk Assessment Training: hazard identification, risk scoring and choosing controls, using your own assessments
- IOSH Working Safely: hazards and risks for employees at every level
- IOSH Managing Safely: assessing and controlling risk for managers and supervisors
- 5 steps to risk assessment
- The hierarchy of control explained
Talk to KeyOstas
Knowing the difference between hazard and risk is where good risk assessment starts. Our Risk Assessment course takes managers and supervisors from spotting hazards to rating and controlling risk, delivered at your site for up to 12 delegates.
Send an enquiry or call +44 (0)330 056 9534.