Understanding Hand Arm Vibration Syndrome Exposure Limits

UNDERSTANDing HAVS EXPOSURE LIMITS: EAV AND ELV

The prevention of Hand Arm Vibration Syndrome (HAVS) is governed by two exposure limits under the Control of Vibration at Work Regulations. To protect your employees, and prevent compensation claims that could permanently damage your company’s reputation, you need to understand and apply these two limits across your entire arsenal of hand-held and hand-guided power tools.

 

What is hand arm vibration syndrome?

Hand Arm Vibration Syndrome or HAVS (white finger) is a serious health condition in which the nerves, blood vessels and joints of the hand, wrist and arm are permanently damaged from overexposure to vibration. Damage from HAVS often occurs slowly over a period of time, making it hard to spot, which is why ensuring all employees work within the exposure limits outlined in the Control of Vibration at Work Regulations. 

 

HAVS Exposure limits

There are two legal exposure limits that determine how much vibration your employees can be in contact with each day. The limits are:

• Exposure Action Value (EAV)
• Exposure Limit Value (ELV)

Before looking at each of these limits in more detail, it is important to understand that both exposure limits are measured over an average eight-hour period (the length of a standard working shift), but even someone working longer than this, must remain within the eight-hour exposure limit. 

In other words, if one employee is working for eight hours, and another employee is working for ten hours, the same eight-hour exposure limit applies. 

This average of eight hours is displayed as A(8) in each exposure calculation.

Over those eight hours, the vibration intensity is measured in meters per second squared and this is displayed as m/s2.

 

understanding eav (exposure action value)

The Exposure Action Value is 2.5m/s2 A(8). This is the limit at which you must take action. Put simply, if your team uses tools that exceed 2.5m/s2 A(8), then action is required to protect them from HAVS.

Tool manufacturers clearly display the vibration output on each hand-held and hand-guided power tool, but often these numbers seem alarmingly high. Many drills for example will show vibration outputs like 15.5 m/s2, which many professionals misinterpret as being immediately over the ELV limit. 

The important thing to notice is that the A(8) is missing, which means this number isn’t averaged out over an eight-hour shift time. Once you complete the HAVS calculation, you see that in fact, you can use that tool for ten minutes at a time without risking overexposure but using it for 15 minutes does put you over the limit. 

Measuring vibration exposure over an average of eight hours is complicated, but there are plenty of free online calculation tools that make it fast and accurate. 

 

taking action if a power tool exceeds eav

The Control of Vibration at Work Regulations states: “Where it is not reasonably practicable to eliminate risk at source(…) 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 most effective way to reduce vibration is by regularly testing and maintaining all hand-held and hand-guided power tools. We’ll look at how to achieve this in more detail at the end.

Other action points include scheduling breaks or job rotation, limiting the length of time tools are used, or using PPE to protect from weather conditions that increase the risk of HAVS.

 

understanding elv (exposure limit value)

ELV is the most exposure an employee is legally allowed to experience in an average eight-hour shift. Under the Control of Vibration at Work Regulations, the ELV is 5m/s2 A(8). If the limit is reached, work must stop.

To support employers in maintaining legal exposure levels, the guidance states:

• Employers will ensure employees are not exposed to vibration levels above an exposure limit value
• If an exposure limit value is exceeded, the employer will reduce exposure to below the limit, identify why the limit was breached, and modify measures to prevent it from being exceeded again

If we use the same common example as before and consider a power tool with a vibration output of 15.5m/s2, it will take 49 minutes to reach the ELV of 5m/s2 A(8). Again, there are many free online calculators that can work this out for you in an instant before you begin working.

combined exposure

Throughout the course of a standard eight-hour shift, many workers will use more than one hand-held or hand-guided power tool. It’s important that they consider their HAVS exposure across all the equipment they use. 

For example, a worker using a drill for 20 minutes will have used a considerable amount of their vibration exposure allowance, but they may need to use a power saw to complete the job. They must calculate the combined exposure across both tools and ensure they remain below the limit.

 

maintaining equipment to keep vibration minimal

By using the vibration output of a tool, you can work out how many minutes a worker can use that tool safely. But if your equipment is poorly maintained that vibration output level will not be accurate. 

Poorly maintained tools omit higher levels of vibration, making it almost impossible to calculate exposure and protect employees from HAVS.

Best practice HAVS testing should happen annually for all hand-held or hand-guided power tools. You can read more about HAVS testing, as well as the risk of compensation claims and more about the effects of HAVS in our previous HAVS blog.

 

a three-in-one service: havs, acoustics, and health checks

Our specialist team of tool testers offer a comprehensive value-add service designed to offer an efficient all-round health check, acoustic check, and HAVS testing service. Using one service provider for all these essential tool health checks reduces tool downtime and keeps your teams working at full capacity.

Our service is provided on-site, either line side (on the shop floor), in our van, or in a designated testing area within your premises. Hand-held and hand-guided tools are tested for vibration issues and acoustic problems at the same time – with both results recorded on the certificate. 

In addition, we provide a full tool health check and repair any faults straight away, followed by a full re-calibration if required. 

Vibration and acoustic testing are best conducted annually, but for tool health checks too, a 3-6 month interval plan is best practice.