How To Measure Vibration Exposure To The EAV

We've already looked at how to calculate vibration exposure to the ELV. The Exposure Limit Value (ELV) is an important value that must not be exceeded. It's the law. But this isn't the only value you need to know about when measuring vibration exposure.

The Control of Vibration at Work Regulations has another exposure limit for vibration at work that you must be aware of, the Exposure Action Value (EAV).

Where an employee is exposed to vibration levels over and above this value, you should look for ways to control vibration. This could be done through elimination or reduction of exposure, or exposure for shorter periods.

What is the Exposure Action Value (EAV)?

The Control of Vibration at Work Regulations set an exposure action value (EAV) of 2.5m/s²A(8).

But how do we calculate when the EAV is reached?

Well, the EAV (2.5) is half the ELV (5), so it would be reached in half the time, right?

Wrong!

Unfortunately, it's not that simple to work out the EAV.

But the good news is that you can follow a similar principle to the steps we followed in the previous blog post to calculate the ELV, to calculate the EAV.

Or you can cheat and use our free havs calculator (we won't tell anyone!).

Before we go into how to calculate the exposure action value (EAV), let's take a moment to discuss what the EAV means. It's not a limit, like the higher exposure limit value (ELV).

Unlike the ELV, you can exceed the EAV.

So why do you need to know about it?

Well, because you need to take ACTION. The EAV is an action value. Any vibration exposure over this value increases the risk of hand-arm vibration syndrome (HAVS), which is painful and irreversible, so it's best avoided!

Actions could include:

• Changing work methods to reduce vibration
• Selecting alternative work equipment to reduce vibration
• Improving maintenance to keep equipment efficient and reduce vibration
• Planning work to reduce exposure
• Limiting the time employees are exposed to vibration
• Rotating work patterns to reduce exposure
• Using additional protective clothing
• Using anti-vibration accessories and attachments to reduce vibration
• Additional training and monitoring to enforce vibration procedures and policies

Your duties are to reduce the risks from vibration to the lowest level reasonably practicable and to reduce exposure to as low as is reasonably practicable if it is above the EAV.

For exposure above the EAV, you should also provide health surveillance to look for signs and symptoms of HAVS.

Calculating the Exposure Action Value (EAV)

Before you can take action, you need to know when the EAV is reached. And before you can calculate exposure levels, you need to know the vibration output of your tools and equipment.

You can get this information from several sources:

• Product information manuals
• Product sales literature
• Manufacturers websites
• Vibration measurement devices

We already covered some of the ways you can find out vibration output in our post how to calculate vibration exposure to the ELV. You can check out that post for more information (under the section 'Finding out vibration levels').

Once you have the vibration output for your tasks or activities, you can calculate the EAV.

EAV in the points-based system

We will be using a points-based system, as this is the easiest way to calculate exposure once we take into account that operatives may be using various vibrating tools throughout a day.

The EAV (or 2.5m/s²A(8)) in our points-based system is 100 points.

If you read the post on calculating the ELV, you may remember that under our points-based system, we were allowed 400 points a day to reach the ELV. This is the limit value, or the maximum exposure, so those 400 points are the maximum you can use in a day.

Even though the EAV at 2.5m/s²A(8) is half the ELV at 5m/s²A(8), you are only allowed a quarter of the points before you reach the EAV. That means you are allowed 100 points a day before we reach the action value.

Are you wondering why you don't get 200 points, since the EAV is half the value of the ELV?

The difference is all to do with how points are calculated and how vibration exposure is measured. Since the ² in m/s² means squared, we multiply the number by itself, and 2.5x2.5=6.25. The ELV is 5x5=25. And 6.25 is a quarter of 25.

You will see another example of this below in the increase between a 5m/s² tool and a 10m/s² tool.

The exposure action trigger in a day in our points-based system is 100 points, which equals the EAV of 2.5m/s²A(8). This means that once you have used 100 points, you must take action to control vibration and reduce the risks.

5m/s² tool example

Next, we will give each tool a number of points per hour. This is how many points you use up for each hour on the tool.

(Output x Output) x 2 = Points

We multiply the vibration value by itself (Output x Output) and then double it. Ok, let's look at a 5m/s² tool.

(5 x 5) x 2 = 50

So that's 50 points per hour when using our 5m/s² tool.

We know we only have 100 points per day before we reach the EAV, so if we divide our 100 points by the points per hour, this tells us how long we can use the tool for.

100 / 50 = 2

2 hours.

Once this time is up, you have reached the EAV, and you need to take action. Your legal duties are to reduce the risks from vibration to the lowest level reasonably practicable and to reduce exposure to as low as is reasonably practicable if it is above the EAV.

10m/s² tool example

Let's look at another example, this time with a higher vibration output. Let's look at a tool with an output of 10m/s².

(10 x 10) x 2 = 200

That's 200 points per hour when using our 10m/s² tool. Note how the vibration output has doubled, but the points per hour have actually quadrupled.

This is because vibration output is squared (multiplied by itself).

Now we divide our 100 points by the points per hour, which tells us how long we can use the tool for.

100 / 200 = 0.5

0.5 hours (half an hour / 30 minutes). Once this time is up, you have reached the EAV, and you need to take action.

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Remember, there is another limit (the Exposure Limit Value or ELV), which must not be exceeded... we talk about calculating the ELV value here.