HAVS Exposure Limits (EAV, ELV And What They Mean)

If you work with vibrating equipment, even if it's occasionally, you need to know about HAVS. HAVS stands for Hand Arm Vibration Syndrome. HAVS is a painful, disabling, and serious condition, that's permanent once it develops.

The problem with HAVS is, that the symptoms can creep up gradually. You might not know you are getting HAVS at first. But the damage cannot be reversed. And once you start getting problems with your hands, it's too late to fix it.

So early preventative action is important if you work with vibrating equipment.

And thats why there are exposure limits in place to protect people who work with vibration. Knowing what the legal exposure limits are can help you stay within the law, and most importantly, protect your health.

What are the HAVS exposure limits?

HAVS exposure limits are defined in the Control of Vibration at Work Regulations. This set of regulations covers the health and safety requirements for vibration exposure at work.

There are two exposure limits, and these are legal limits as to the amount of vibration you can be in contact with daily. The two limits for hand-arm vibration are the exposure limit value (ELV) and the exposure action value (EAV).

4.—(1) For hand-arm vibration—

1. the daily exposure limit value is 5 m/s2 A(8);
2. the daily exposure action value is 2.5 m/s2 A(8),

Before we go into more detail about what each exposure limit means, let's break down those values so you understand how vibration exposure is calculated.

m/s² = metres per second squared. This is a measure of the intensity of vibration exposure, as in the level of vibration.

A(8) = average over 8 hours. This is a measure of the duration of vibration exposure, as in, how long you are exposed.

So, the 'A(8)' part of the exposure limits defined in the regulations is telling us that the limits are for an average over 8 hours. The 'm/s²' part tells us the level of vibration you can be exposed to.

If you're still confused, don't worry - it should become much clearer once we look at what each of the HAVS exposure limits means with some examples below.

It's also important to remember that these are daily exposure limits. They are averaged over 8 hours because that is a standard work shift, but it doesn't mean that every 8 hours you can restart your vibration allowance. If you are going to be exposed for 10 hours, you still need to stay below the 8-hour average limit.

EAV (Exposure Action Value)

The first exposure limit you will hit is the exposure action value (EAV). It's not a limit in the sense that you cannot go through it, but it is a value after which you must take action.

So, if your vibration exposure exceeds the action value, you need to take action.

The EAV is 2.5 m/s² A(8)

What if a tool is over the EAV?

If I use a tool, for example, a Makita rotary hammer drill to drill into concrete, with a vibration output of 15.5 m/s², am I immediately over the exposure action value?

That's actually a common misunderstanding. And it's easy to see why you would come to that kind of conclusion. 15.5 is a way bigger number than 2.5 after all!

But actually, it isn't the case.

Don't forget that the exposure limits in the regulations are averaged over 8 hours. If you are only going to use the tool for 10 minutes, then averaged over 8 hours you would be under the EAV.

But, since it has quite a high vibration output, if you use that same drill for 15 minutes you would be over the EAV.

How is the 8-hour average calculated?

Calculating the time-weighted average over 8 hours is a little bit complicated. We use a points-based system to do it, which is the subject of another post.

We cover calculating the EAV in more detail here if you want to find out how to do it, or you can use our free HAVS calculator to measure your vibration exposure.

It's important to calculate your vibration exposure because where it is likely to be reached, you must take action to reduce exposure.

What actions do you need to take?

(2) Where it is not reasonably practicable to eliminate risk at source pursuant to paragraph (1) and an exposure action value is likely to be reached or exceeded, the employer shall reduce exposure to as low a level as is reasonably practicable by establishing and implementing a programme of organisational and technical measures which is appropriate to the activity.

The regulations require employers to take appropriate organisational and technical measures to reduce exposure.

These actions to reduce the risk of HAVS from vibration exposure might include:

• changing the way you work or the equipment used to produce lower vibration levels,
• visual checks on equipment condition
• keeping tools sharp and maintained
• replacing tools
• limits on the duration tools can be used for
• breaks and job rotation
• training
• clothing to protect from cold and damp (as these conditions can increase the risk of HAVS)

ELV (Exposure Limit Value)

The upper HAVS exposure limit is the exposure limit value (ELV). This one really is a limit, you are legally not allowed to exceed it*.

The ELV is 5 m/s² A(8)

(4) Subject to regulation 3(2) and (3) and paragraph (5), the employer shall–

1. ensure that his employees are not exposed to vibration above an exposure limit value; or
2. if an exposure limit value is exceeded, he shall forthwith–
   • reduce exposure to vibration to below the limit value;
   • identify the reason for that limit being exceeded; and
   • modify the measures taken in accordance with paragraphs (1) and (2) to prevent it being exceeded again.

What happens when you reach the ELV?

The regulations are clear that the exposure limit value (ELV) must not be exceeded, and if it is, work should stop and action should be taken to prevent the limit from being exceeded again.

*The only exception is where an employee is usually below the EAV and may occasionally exceed the exposure limit value, however, there are extra legal requirements for this. The average vibration exposure over the week must still be below the ELV, there must be evidence to show the risk is lower than constant exposure, and there must be increased health surveillance.

What if a tool is over the ELV?

Back to our Makita rotary hammer drill used to drill into concrete, 15.5 is a way bigger number than 5 still, so are you prevented from using this tool because it is over the ELV?

Well, just like the EAV, the ELV is also calculated based on an average over 8 hours. Although the drill has a vibration output of 15.5, you can use this tool for 49 minutes before reaching the ELV.

Find out how to calculate the ELV here and use our free HAVS calculator.

Vibration exposure in the real world

Getting exposure levels from the manufacturer is a good way of knowing the approximate vibration output for a tool. But it's important to be aware that the vibration levels you are exposed to can be impacted by both the tool, and what you do with it.

The hammer drill we used for our examples has a vibration output of 15.5 m/s² when hammer drilling concrete, but a much lower vibration output of 4.5 m/s² when drilling metal.

So think about the tool, the condition it's in, and the materials you are working with when you consider vibration exposure.

And in the real world, you probably don't just use one tool each shift. You might use multiple vibrating tools throughout the day.

Since exposure limits apply to your total exposure, you need to calculate your combined exposure to see if you hit either of the HAVS exposure limits.

For example, if you used the drill for 30 minutes, you will have already used the majority of your vibration allowance. You'll need to take this into account before you use any more vibrating equipment.

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To help you calculate vibration exposure and stay within the HAVS exposure limits, you can use our free HAVS calculator for one or multiple tools.