Hand-Arm Vibration (HAV): When Manufacturer Data Doesn’t Reflect Real Exposure

Hand-arm vibration (HAV) remains a common risk across a wide range of industries, particularly where powered tools are used regularly. Under the Control of Vibration at Work Regulations, employers are required to assess and control exposure to reduce the risk of conditions such as Hand-Arm Vibration Syndrome (HAVS).

In practice, however, exposure is often estimated using manufacturer-provided vibration data and assumed trigger times. While this can be a useful starting point, it does not always reflect how tools are used on site. In many cases, HAV risk assessments are typically based on:

• Declared vibration magnitudes from tool manufacturers

• Standardised or assumed usage times

• Generic exposure calculators

This approach can provide a broad estimate of exposure, but relies heavily on the assumption that tools are being used under conditions similar to those in which they were tested.

Standards and Declared Vibration Data

Vibration magnitudes provided by manufacturers are typically derived from standardised test methods, such as those defined in ISO 5349 and related tool-specific codes including ISO 20643.

While this provides a consistent basis for comparison, these values are obtained under controlled conditions and may not reflect how tools are used in practice.

In addition, older equipment or legacy data may not align with current testing standards, meaning declared values should be treated with caution where working conditions differ.

Where This Breaks Down & Risks

In practice, tools are frequently used outside of their original design specification or test conditions. Examples include:

• Different materials (e.g. softer or composite substrates such as plastics or fibreglass)

• Increased or reduced applied force

• Worn or poorly maintained tooling

• Variations in operator technique

These factors can significantly affect vibration levels, meaning actual exposure may differ substantially from declared values. However, where manufacturer data is relied upon without validation, this can lead to:

• Underestimation of vibration exposure

• Incorrect trigger times

• False assumptions of compliance

• Inadequate control measures

Real-World Assessment: When Exposure Is Overestimated

In some cases exposure may be overestimated, leading to unnecessarily restrictive working practices. In a recent assessment we carried out, hand-held power tools were being used to cut and work materials such as HDPE and fibreglass. The only available vibration data for the tools related to heavier applications, such as metal cutting and grinding.

Based on this information, exposure had been estimated conservatively, resulting in relatively restrictive trigger times. However, when vibration was measured under actual working conditions, levels were found to be lower than the declared values associated with heavier-duty use. This allowed trigger times to be adjusted to better reflect the task being carried out.

In this case, reliance on generic or non-representative data had led to an overestimation of risk. By assessing vibration in practice, exposure could be managed more accurately, while also supporting more efficient working arrangements.

This highlights that while a cautious approach is often appropriate, assessments should still reflect how tools are used in practice to ensure controls are both effective and proportionate.

What a HAV Assessment Involves

A more robust approach to HAVs assessment considers how tools are used in practice. This may include:

• Measurement of vibration under real working conditions

• Task-based exposure assessment

• Review of tool condition and maintenance

• Consideration of operator technique and variability

This allows exposure to be assessed more accurately and control measures to be targeted appropriately. Where higher exposure is identified, control measures may include:

• Limiting exposure duration

• Selecting more suitable tools

• Improving maintenance and condition

• Reviewing working methods

In some cases, adjustments to process or tooling can significantly reduce exposure.

Practical Takeaway

Manufacturer vibration data can provide a useful reference point for standard tool use, but it should not be assumed to represent actual exposure in every case. Where tools are used outside standard conditions, or where exposure is uncertain, further assessment is often required to ensure risks are fully understood and controlled.

At NOHH Ltd, we carry out HAV assessments based on real working conditions, including measurement and task-based exposure evaluation where required. If you’re unsure whether your current assessments reflect how tools are actually used on site, feel free to get in touch.