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15th November, 2018

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

If you work with vibrating equipment, even occasionally, then you need to know about HAVS and the exposure limits that are in place to protect you. Knowing what the legal exposure limits are can help you stay within the law, and most importantly, protect your health.

HAVS stands for Hand Arm Vibration Syndrome, which is a painful, disabling and serious condition that's permanent once it develops. The problem with HAVS is, the symptoms can creep up gradually, but the damage cannot be reversed, so early, preventative action is important if you work with vibrating equipment.

Exposure Limits

There are two exposure limits when it comes to HAVS, and these are legal limits as to the amount of vibration you can be in contact with on a daily basis. These limits are defined in the Control of Vibration at Work Regulations. There are two limits for hand-arm vibration, the exposure limit value (ELV) and the exposure action value (EAV).

Exposure limit values and action values

4.—(1) For hand-arm vibration—

(a)the daily exposure limit value is 5 m/s² A(8);

(b)the daily exposure action value is 2.5 m/s² A(8)

The Control of Vibration at Work Regulations 2005

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 for.

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, it should become much clearer once we go on to look at what each of the HAVS exposure limits means 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 that after which you must take action.

The EAV is 2.5 m/s² A(8)

Does that mean that if you use a tool, for example, a Makita rotary hammer drill to drill into concrete, with a vibration output of 15.5 m/s², that you are immediately over the exposure action value? 15.5 is a way bigger number than 2.5 after all!

Actually, it doesn't mean that. Don't forget that the exposure limits in the regulations are averaged over 8 hours. If you are only going to use it for 10 minutes you would be under the EAV, but if you use it for 15 minutes you would be over the EAV. Calculating the time-weighted average over 8 hours 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.

6.—(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 Control of Vibration at Work Regulations 2005

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, ensuring maintenance and visual checks check equipment condition and keep tools sharp, strict limits on the duration tools can be used for, breaks and job rotation, training and 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)

6.—(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–
    1. reduce exposure to vibration to below the limit value;
    2. identify the reason for that limit being exceeded; and
    3. modify the measures taken in accordance with paragraphs (1) and (2) to prevent it being exceeded again.
The Control of Vibration at Work Regulations 2005

The regulations are quite 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 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.

Back to our Makita rotary hammer drill being 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. So, you can use this tool for 49 minutes before reaching the ELV. You can find out how to calculate the ELV here, and also use our free HAVS calculator.

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.

vibration levels
MAKITA HR2470 Manual

One last thing to remember. You might use multiple vibrating tools throughout a day, and 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, and need to take this into account before you use any more vibrating equipment.

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.

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This article was written by Emma at HASpod. Emma has over 10 years experience in health and safety and BSc (Hons) Construction Management. She is NEBOSH qualified and Tech IOSH.

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