Hand-arm vibration exposure occurs when vibration passes from powered equipment, a workpiece or a process into the hands and arms. An assessment determines the vibration magnitude reaching the hand, the time for which that exposure occurs and the resulting daily exposure expressed as A(8). The result is then compared with the applicable action and limit values. The calculation itself is only one part of the assessment. Reliable conclusions depend on representative vibration data, realistic trigger times and an accurate description of every vibrating operation completed during the working day. A precise calculation based on unsuitable magnitude data or estimated exposure times may give a misleading result. Hand-arm vibration assessment is distinct from whole-body vibration assessment, which considers vibration transmitted through a seat, platform or other supporting surface and is addressed separately on the whole-body vibration assessment page.
A(8) is the daily vibration exposure normalised to a reference duration. It allows a relatively high vibration magnitude used for a short period to be compared with a lower magnitude experienced for longer. The calculation uses the vibration magnitude, identified as ahv, and the period during which the hand is exposed to that magnitude.
Under ADOSH-SF CoP 3.1 Vibration, applying within the Emirate of Abu Dhabi, A(8) is calculated as ahv multiplied by the square root of the exposure duration divided by a reference duration of 8 hours, equivalent to 28,800 seconds. The same Code sets the hand-arm vibration daily exposure action value at 2.5 m/s² A(8) and the daily exposure limit value at 5 m/s² A(8).
The magnitude ahv is not a measurement in a single direction. It is the root-sum-of-squares of the frequency-weighted root-mean-square accelerations in the x, y and z directions at the surface in contact with the hand. The measurements use the W_h frequency weighting defined in BS EN ISO 5349-1:2001. Where both hands are exposed, ADOSH-SF CoP 3.1 requires the greater of the two hand magnitudes to be used when determining daily exposure within the Emirate of Abu Dhabi.
The action value is a trigger for managing and reducing risk. It is not a boundary below which vibration can automatically be disregarded. The limit value is a maximum daily exposure value, but an assessment should still identify reasonably practicable reductions rather than treating exposure just below the limit as an acceptable target.
Vibration magnitude data may come from task-specific workplace measurements, information supplied by the equipment manufacturer, the supplier, recognised vibration databases or previous measurements of sufficiently similar equipment and work. The assessor must decide whether the information represents the tool, accessory, workpiece, condition and operating method actually found at the workplace.
Manufacturer declarations are commonly produced under controlled standardised test conditions. They are useful when comparing equipment and may support an initial assessment, but they do not necessarily represent vibration during normal production. HSE research has found that declared emission data can underestimate in-use vibration for some categories of power tool and should be corroborated before being relied upon as the sole basis of an exposure assessment. This HSE material is recognised practice rather than UAE law.
Real-use magnitude is affected by the condition of the tool, maintenance, bearing wear, balance, operating pressure, consumable selection and the sharpness of blades, bits, discs or chisels. A worn consumable may require greater force or longer contact with the workpiece. The hardness, dimensions and support of the workpiece can also alter vibration substantially.
Operator behaviour is another source of variation. Grip force, feed force, posture, tool orientation and the technique used to complete the task can change the magnitude transmitted to the hands. Measurements should therefore represent normal competent operation rather than an artificial demonstration selected only because it produces a convenient result.
Direct measurement is appropriate where reliable representative data are unavailable, the work differs materially from standard test conditions, several operating modes are used or the consequences of uncertainty could affect the control decision. The accelerometer should be mounted as close as reasonably practicable to the hand contact position without materially changing the grip or operation.
Trigger time is the period during which the equipment is operating and transmitting vibration to the hand. It is not normally the full shift duration, the time for which the tool is signed out or the total period spent in the work area. Set-up, marking, inspection, repositioning, changing consumables and other non-vibrating activities may occupy much of the task without contributing directly to hand-arm vibration exposure.
Trigger time is often the weakest part of an assessment because it is easily estimated from memory rather than observed. An employee may describe the tool as being used throughout a task even though actual powered contact occurs intermittently. The opposite error is also possible where numerous short uses are overlooked.
A competent person may establish exposure duration through direct observation, timed task studies, review of production cycles, equipment counters, work records, video review or structured discussion with employees and supervisors. The selected method should capture variation between employees, products, materials and work periods. A single unusually quiet or unusually intensive period should not be treated as representative without justification.
Trigger time should be recorded separately for each tool, operating mode or process associated with a different vibration magnitude. Where a task includes a low-vibration preparation stage and a higher-vibration finishing stage, combining both under a single average duration may obscure the contribution from the more significant operation.
Uncertainty should be handled transparently. Where duration cannot be measured precisely, a cautious realistic estimate can be used and the range of possible exposure considered. The report should explain whether the conclusion would change if the actual trigger time were moderately higher than the selected value.
Many employees use more than one vibrating tool or complete several operations during a working day. These exposures cannot be assessed by taking the highest individual A(8) result alone or by adding the vibration magnitudes directly.
Under ADOSH-SF CoP 3.1, applying within the Emirate of Abu Dhabi, multiple hand-arm vibration operations are combined through the partial-exposure calculation. Each operation's squared vibration magnitude is multiplied by its exposure duration, the contributions are added, and the total is normalised to the 8-hour reference duration before the square root is taken.
This approach means that several apparently modest tasks can produce a significant combined daily exposure. The assessment should therefore include all regular vibrating activities, including brief operations repeated frequently and tasks completed away from the employee's normal workstation.
Where tools are held in both hands, measurements or suitable data should represent each hand position where the magnitudes may differ. ADOSH-SF CoP 3.1 requires the greater hand magnitude to be used within the Emirate of Abu Dhabi rather than averaging the two hands.
The assessment should also consider foreseeable variation. Different attachments, materials, maintenance conditions or production demands may create several exposure profiles for the same job title. A representative assessment may therefore require more than one daily scenario rather than a single result presented as universally applicable.
Hand-arm vibration syndrome is a collective term covering vascular, sensorineural and musculoskeletal effects associated with repeated hand-transmitted vibration. Its clinical presentation varies between individuals, and similar symptoms may have other causes.
The vascular component is commonly described as vibration white finger. Episodes involve disturbance of the blood supply to parts of the fingers, often producing temporary blanching followed by changes in colour or sensation. Cold conditions may make vascular symptoms more noticeable.
Sensorineural effects may include tingling, numbness, altered touch sensation and reduced ability to distinguish temperature or handle small objects. Hand-transmitted vibration is also associated with carpal tunnel syndrome in some exposed workers. These conditions should not be diagnosed from an exposure calculation or workplace questionnaire alone.
Under ADOSH-SF CoP 3.1, applying within the Emirate of Abu Dhabi, employees exposed or likely to be exposed at or above the 2.5 m/s² A(8) action value must be placed under appropriate health surveillance in accordance with ADOSH-SF CoP 5.0 Occupational Health Screening and Medical Surveillance. The programme includes medical evaluation by a physician experienced in vibration-related injury who understands the work environment, documentation of links between exposure and identifiable effects, review of job duties and consideration of alternative or light duties following diagnosis.
Employees reporting finger blanching, persistent tingling, numbness, reduced grip, loss of dexterity or other relevant symptoms should be referred to occupational health. The workplace assessment supplies exposure information, but it does not replace clinical evaluation.
Construction work is where most hand-arm exposure arises, and a construction-specific treatment covers which site tools drive exposure and why trigger time dominates.
ADOSH-SF CoP 3.1 Vibration, Version 4.0 dated 15 July 2024, applies to all employers within the Emirate of Abu Dhabi. Codes of Practice form the mandatory layer of ADOSH-SF, provide minimum mandatory OSH technical requirements and apply to entities regardless of risk classification. The responsible authority is the Abu Dhabi Public Health Centre. Under ADOSH-SF CoP 3.1, and only within the Emirate of Abu Dhabi, the hand-arm vibration action value is 2.5 m/s² A(8) and the limit value is 5 m/s² A(8). Exposure monitoring and medical surveillance records must be retained for the period of employment plus 30 years, while training and compliance records must be retained for five years. Medical records must remain confidential.
No separate federal UAE occupational vibration instrument and no Dubai Municipality occupational vibration instrument have been identified for this resource. The separate Occupational Standards and Guideline Values document is recorded by ADPHC as suspended and is not the source of any figure on this page. Foreign regulations, standards and HSE guidance may inform recognised practice but do not create UAE legal duties.
It may be sufficient where it clearly represents the equipment, accessory and work method being assessed and is supported by information about likely vibration during real use. Where the declared value comes from a standardised test that differs materially from the workplace task, representative workplace data or another corroborated source should be used.
Not necessarily. Trigger time is the period during which vibration is being transmitted to the hand. Time spent carrying, positioning, adjusting or inspecting an inactive tool normally does not contribute directly, although the assessment must reflect how the equipment actually operates.
Yes. The contact position, handle design and operating force can create different magnitudes at each hand. Under ADOSH-SF CoP 3.1, applying within the Emirate of Abu Dhabi, the greater of the two hand magnitudes is used to establish daily exposure.
Anti-vibration gloves are not a substitute for eliminating or reducing vibration at source. ADOSH-SF CoP 3.1 treats gloves and anti-vibration mats as personal protective equipment of last resort, and their effectiveness must be evaluated under ADOSH-SF CoP 2.0 Personal Protective Equipment.
The employee should be referred to occupational health for appropriate evaluation. The employer should preserve the exposure information, review the employee's work and controls, and act on any occupational health recommendations without attempting to diagnose the condition through the vibration assessment.