A hazard is anything that has the potential to cause harm, while a risk is the chance that the harm actually happens, together with how serious it could be. The two words are not interchangeable, and getting them straight helps with both real site decisions and test questions. This article is independent study material and is not affiliated with CSCS or CITB.
Key takeaways
- A hazard is the source of potential harm, such as an open edge, a live cable or a hazardous dust.
- A risk is the chance, high or low, that someone is harmed by a hazard, together with how serious the harm could be.
- The same hazard can carry a low risk or a high risk depending on the conditions and the controls in place.
- You can remove a hazard completely, but you can usually only reduce a risk.
- A risk assessment is the tool used to link the two: it looks at hazards, who could be harmed and what precautions are needed.
What each word means
The everyday definitions are simple. A hazard is anything that may cause harm, such as chemicals, electricity or working from ladders. HSE's risk pages describe hazards as what could cause injury or illness, and risk as how likely it is that someone could be harmed and how seriously.
A useful way to hold the difference in your head is this:
- Hazard answers the question "What could hurt someone?"
- Risk answers the question "How likely is it to happen, and how bad would it be?"
Notice that a risk always has two parts. One is likelihood. The other is severity. A hazard that is very unlikely to cause harm but could kill someone still deserves careful attention, because the severity is so high. A hazard that is very likely to cause a minor scrape is also worth controlling, but in a different way.
Two construction examples
Example 1: an unprotected edge
The hazard is the drop at the edge of a floor slab or roof. The edge itself is not "dangerous" in the way a running saw is. It becomes dangerous because someone could fall from it.
The risk depends on circumstances:
- How often do people work or walk near the edge?
- Is there a guardrail, a barrier or nothing at all?
- How far is the fall, and what is below?
- Is the surface dry, tidy and well lit, or wet and cluttered?
If the edge is fully guarded and no one works near it, the risk of a fall is low. If people carry materials along an open edge in poor light, the risk is high. The hazard is the same in both cases. What changed is the likelihood and the control measures.
Example 2: dust from cutting
The hazard is the dust created when you cut or grind certain materials. Breathing it in can harm health over time.
The risk depends on what is being cut, how long the task lasts, whether it is done indoors or in the open, and what controls are in place, such as water suppression, extraction or suitable respiratory protective equipment. A short job outdoors with good controls carries a lower risk than a long job in a closed room with none. For a fuller look at substances like this, see the articles on hazardous substances and COSHH from the site safety terms overview.
Same hazard, different risk
The table below shows how the same hazard can sit at very different risk levels. It does not use scores, because a numerical rating would need to come from a real assessment of your own site.
| Hazard | Conditions that keep risk lower | Conditions that raise risk |
|---|---|---|
| Unprotected edge | Edge guarded, area restricted, tidy and well lit | Open edge, people passing close by, cluttered or wet surface |
| Trailing cable | Cable routed overhead or along a wall, walkway kept clear | Cable across a busy walkway at night or in a rush |
| Dust from cutting | Water suppression or extraction, good ventilation, right respiratory protective equipment | No controls, enclosed space, long exposure |
| Moving plant | Segregated routes, trained marshaller, clear signs | Pedestrians sharing the route, poor visibility |
Where hazard and risk fit in a risk assessment
A common approach to risk assessment has five steps (a general approach, not HSE's current wording). The first two deal with hazards and people, and the middle ones deal with risk:
- Identify the hazards.
- Decide who might be harmed and how.
- Evaluate the risks and decide on precautions.
- Record your findings and put them into practice.
- Review the assessment and update it if needed.
So you spot the hazard, then judge the risk, then decide what to do. If a hazard can be removed entirely, the risk from it disappears. If not, you reduce the risk with controls. The wider process on a live site is covered in risk assessment on site.
Worked exercise
Try this original question before reading the answer. It is written for practice and is not taken from any official test.
Question: A scaffold lift has a missing toe board, and a worker is about to carry bricks along it. Which option correctly describes the situation?
- A. The missing toe board is the risk, and the worker is the hazard.
- B. The possible fall of materials or people is the hazard, and the chance and seriousness of someone being hurt is the risk.
- C. Hazard and risk mean the same thing, so either word is fine.
- D. There is no hazard until someone is actually injured.
Answer: B.
Why: The thing that could cause harm, such as materials or people falling, is the hazard. The risk is the chance of that happening and how serious the result could be, and it is higher here because a protective feature is missing and people are working on the lift. Option A reverses the words and wrongly calls a worker a hazard. Option C is wrong because the terms have different meanings. Option D is wrong because a hazard exists whether or not harm has yet happened, which is why we assess and control it beforehand.
Quick checklist for spotting the difference
- [ ] Can I point to the thing that could cause harm? That is the hazard.
- [ ] Have I thought about how likely harm is in these conditions?
- [ ] Have I thought about how serious the harm could be?
- [ ] Are there controls in place, and are they working?
- [ ] Has anything changed that makes the risk higher than planned?
More practice on this and other terms is available on the free practice questions page. Practice scores are not an official result.
A worked example: a delivery morning on a small site
Here is how the two words work together on an ordinary morning. A lorry is due to deliver plasterboard to a site where a few trades are already working.
Step 1, spot the hazards. Walking the route from the gate to the storage area, you notice moving vehicles, a pile of offcuts near the path, a cable running across the yard and a stack of board that must be carried upstairs by hand. Each one is something that could cause harm. At this point you are only naming them.
Step 2, think about who could be hurt. Delivery drivers, people on foot near the gate, and the workers who will carry the board are all exposed in different ways.
Step 3, judge the risk. The vehicle hazard has a low likelihood of harm if pedestrians are kept clear and someone guides the lorry, but the harm if it goes wrong would be serious. The offcuts have a higher likelihood of a trip but usually a less serious result. The hand carrying depends on the load, the distance and the stairs, so you would look at it separately.
Step 4, decide the precautions. Keep walkers out of the vehicle area, clear the offcuts, reroute or cover the cable, and agree how the board will be moved. These are examples of general practice, not a full plan.
Step 5, check it works. Look again once the lorry arrives. If the weather changes or another trade moves in, the risk may have changed even though the hazards have not.
Notice that nothing here needed a score. The thinking is what counts: name the hazard, judge likelihood and severity, then act.
Wording traps in test-style questions
In practice questions like the ones on this site, small differences in wording often decide the answer. These are the traps to watch for:
- Swapped words. An option that calls the person the hazard and the unguarded edge the risk has the terms the wrong way round.
- "No hazard until someone is hurt." A hazard exists before any harm happens. That is why we assess in advance.
- "The hazard is the chance of harm." The chance is the risk, not the hazard.
- "Removing the hazard leaves the risk." If you remove the hazard completely, the risk from it goes too.
- Ignoring severity. A rare event that could be very serious still needs attention.
When you read a scenario, ask the two questions from earlier in this article: what could hurt someone, and how likely and how bad would it be? Then pick the option that keeps the two meanings apart. For wider vocabulary, see the site safety terms overview and the guide to risk assessment on site.
FAQ
What is the simplest way to explain hazard vs risk?
A hazard is what could cause harm, and a risk is how likely that harm is and how bad it would be. A slippery floor is the hazard. The risk is the chance someone slips and the injury that could follow.
Can a hazard have no risk?
A hazard can carry a very low risk if it is well controlled or if no one is exposed to it, but you cannot say there is no risk while the hazard and a person are both present. If a hazard is removed completely, the risk from that hazard goes with it.
Which comes first in a risk assessment, the hazard or the risk?
You identify the hazard first and then judge the risk. The five steps start with identifying hazards and deciding who might be harmed, then move on to evaluating the risks and choosing precautions.
Do I need to calculate a risk score for the CITB test?
Understanding the idea does not need a score. This site cannot say what the official test contains, so check the CITB pages. Check the official CITB pages for the current test format, as this site is independent.
Sources
Independent guide, not affiliated with, authorised by, approved by or endorsed by CSCS or CITB. Last updated 2026-10-08.