Residual Risk: How To Manage The Risks You Can't Stop

If you have done a good job creating a risk assessment for your work and you've put health and safety controls in place, then you should be totally safe and risk-free - right?

Not quite. Because of residual risk.

What is residual risk?

Residual risk can be defined as the risk that remains when the rest of the risk has been controlled.

residual [adjective]
remaining after most of something has gone.

Residual risk is the risk that remains after most of the risks have gone. And most of the risks have gone because you have put control measures in place to remove them (usually during a risk assessment process).

But if you have done a risk assessment, then why is there still a remaining risk? Shouldn't that all be handled by the risk assessment?

Well - risk can never be zero. Hopefully, you were able to remove some risks during the risk assessment. The best way to control risk is to eliminate it entirely. No risk. No problem.

But you can't remove all risks. You'll need to control any risks that you can't eliminate. And that means reducing the risk. If you reduce the risk, you make it lower, but there is still a risk (even if it's really low).

There's no job on earth with no risks at all. Even if you only read books - you could get a papercut when you flip the page.

There will always be some level of residual risk.

You are not expected to eliminate all risks, because, quite simply it would be impossible.

For example, you can't eliminate the risks from tripping on stairs. But just for fun, let's try.

To start, we would need to remove all the stairs in the world. Let's imagine that is possible - would we replace them with ramps? Now we have ramps, is the risk zero? But even then, people could trip up the ramp simply because the floor level is rising. Even if we got rid of all stairs and ramps, and only had level flooring. People could still trip over their shoelaces. We could remove shoelaces, but then they could trip when their loose shoes fall off.

Sometimes, removing one risk can introduce others. And things can get a little ridiculous too!

As you can see, there will always be some level of residual risk, but it should be as low as reasonably practicable. As in, as low as you can reasonably be expected to make it.

As low as reasonably practicable is a legal health and safety phrase, find out more in the ALARP principle with 5 real-world examples.

How to calculate residual risk

Residual risk can be calculated in the same way as you would calculate any other risk. A risk is a chance that somebody could be harmed. And so you can measure risk by:

Likelihood x Severity = Risk

The result from your calculation should tell you if the risk is residual, or if it's a risk that needs to be controlled.

If it is highly likely that harm could occur, and that harm would be severe, then the risk is high. This wouldn't usually be an acceptable level of residual risk.

But if the remaining risk is low (it is unlikely to harm anyone and that harm would be slight) then this could be an acceptable level of residual risk (based on the ALARP principle).

Comparison of option with best practice, and confirmation that residual risks are no greater than the best of existing installations for comparable functions.

It's important to calculate residual risk, especially when comparing different control measures. If you are planning to introduce a new control measure, you need to know that it will control the hazards and reduce the residual risk as low, or lower than any current controls you have in place.

For example, if you reduce the risk of fire by eliminating flammable substances, but replace them with toxic substances, you've introduced a new health hazard for your workers. The residual risk of fire may be lower, compared to the existing fire safety controls you have, but it's created a higher overall risk by introducing new toxic substances instead.

Need help calculating risk? You can use our free risk assessment calculator to measure risks, including residual risk.

How to control residual risk

Residual risk isn't an uncontrolled risk. Don't confuse residual risk with inherent risks.

An inherent risk is an uncontrolled risk. It's the risk level before any controls have been put in place to reduce the risk.

A residual risk is a controlled risk. It's the risk level after controls have been put in place to reduce the risk.

Residual risk should only be a small proportion of the risk level that would be involved in the activity if no control measures were in place at all.

In health and safety, you can look at residual risk as being the risk that cannot be eliminated or reduced further. This could be because there are no control measures to prevent it. Or that to reduce that risk further you would introduce other risks. Or that it would be grossly disproportionate to control it.

To control residual risk to its lowest possible level, you need to pick the best control measure, or measures, for a task.

The option or combination of options, which achieves the lowest level of residual risk should be implemented, provided grossly disproportionate costs are not incurred.

While you are not expected to eliminate all risks, you are expected to reduce risk, as much as is reasonable. So, this means, when evaluating or deciding on controls, you should look at how you can get the lowest level of residual risk.

Remember, if the residual risk is high, ALARP has probably not been achieved.

Examples of residual risk

Think of any task in your business. You will find that some risks are just unavoidable, no matter how many controls you put in place. And that remaining risk is the residual risk.

Here are some real-world examples.

The staircase

The staircase example we gave earlier shows how there is always some level of residual risk. We can control it, by installing handrails and making sure that the stairs are kept clear and in good condition. Not allowing any trailing cables or obstacles to be located on the stairs. But some risk remains.

If you have stairs in your workplace, there is a small chance that someone could trip up, or down the stairs. Hopefully, they will be holding the handrail and this will prevent a fall.

Using ladders

Another example is ladder work. Ladders are not working platforms, they are designed for access and not for work at height. Ladders don't have full edge protection, and it is difficult to carry out tasks safely from them.

However, for some short-duration work, it may not be possible, or practical, to bring in other, safer work at height equipment. Scaffolding to change a lightbulb? Not likely!

But there is a residual risk when using a ladder. Your risk assessment should assess if that residual risk is reasonable for your task, or if other equipment would be more suitable.

Knives and blades

Working with sharp edges like scissors, knives, or blades will always carry some elements of residual risk. If you can cut materials, you can slice your skin. But if your job involves cutting by hand, you need them.

You can reduce the risk of cuts with training, supervision, guards and gloves, depending on what is appropriate for the task. But at some level, risk will remain.

Manual handling

You can control the risks from manual handling by making sure people don't lift more than they can handle, that the loads are safe and routes are clear. But that doesn't make manual handling 100% safe.

There's still a chance that someone could drop the item they are carrying, even if you provide gloves that improve grip.

---

Some risks are part of everyday life. If you try to eliminate risks entirely, you might find you can't carry out a task at all.

But you should make sure that your team isn't exposed to unnecessary or increased risk. Control risks so that the residual risk remaining is low enough that no one is likely to come to any significant harm.

Make sure you communicate any residual risk to your workforce. You can do this in your risk assessment.

Need help measuring risk levels? Use the free risk assessment calculator to list and prioritise the risks in your business.