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EUROPEAN UNION HUMAN VIBRATION DIRECTIVE AND ANSI S2.70

Introduction

The European Union (EU) adopted its Human Vibration Directive on April 5, 2002. This directive establishes health risk assessment guidelines with respect to human exposure to hand-arm and whole-body vibration. ANSI S2.70, Guide for the Measurement and Evaluation of Human Exposure to Vibration Transmitted to the Hand, was adopted in the U.S. in 2006. The guidelines presented in both of these documents with regard to assessing the health risk associated with worker exposure to hand-transmitted vibration are very similar. The EU Human Vibration Directive carries the weight of law in member nations within the EU and specifies health risk guidelines that must be met. ANSI S2.70 is a voluntary consensus standard within the U.S. It does not have the weight of law. It can only recommend health risk guidelines that should be met. The following presents information that is either implied by or contained within these two documents.

Definition of Hand-Arm Vibration and Hand-Arm Vibration Syndrome

Hand-arm vibration is defined in the EU Human Vibration DIrective as:

the mechanical vibration that, when transmitted to the human hand-arm system, entails risks to the health and safety of workers, in particular vascular, bone or joint, neurological, or muscular disorders.

Hand-arm vibration syndrome (HAVS) is defined in ANSI S2.70 as:

the complex of peripheral vascular, neurological, and musculoskeletal disorders of the hand and arm that are associated with industrial exposure to hand-transmitted vibration.

Daily Vibration Exposure Values

The daily vibration exposure values are to be obtained in accordance to the procedures specified in ISO 5349 Parts 1 and 2. The daily vibration exposure values are obtained from the vibration total values, as specified below.

Figure 1

The quantity used to describe vibration transmitted to the hand is the root-mean-square (rms) acceleration, a_hw(rms) (m/s²), that is given by:

where a_hw(t) (m/s²) is the instantaneous The ISO frequencyus single axis ISO frequency-weighted acceleration value as a function of time, and T (s) is the integration time. The instantaneous ISO frequency-weighted acceleration is obtained by passing the acceleration signal through a filter network that is described by Figure 2.

Figure 2

The vibration total value is obtained from the square root of the sum of the squares of the measured rms ISO-weighted acceleration values in the x, y, and z directions, as shown in Figure 1. In equation form, the vibration total value, a_hv, is given by:

where a_hwx, a_hwy, and a_hwz are the measured rms ISO-weighted acceleration values in the x, y, and z directions, respectively.

If the vibration total value associated with the hand-arm vibration exposure of a worker is made up of several operations, each with different vibration amplitudes, then the vibration total value is obtained from:

where a_hwi is ISO-weighted vector-sum acceleration value of the ith operation, T_i is time duration of the ith operation, n is the total number of operations, and T is total time associated with the n operations.

The daily vibration exposure value, A(8), standardized to an 8-hour reference period is:

where T is the total exposure time associated with a_hv.

Daily Exposure Action and Limit Values

The Human Vibration Directive specifies the following 8-hour daily exposure action and limit values:

Daily Exposure Action Value: 2.5 m/s² standardized to an 8-hour reference period
Daily Exposure Limit Value: 5.0 m/s² standardized to an 8-hour reference period.

With regard to the EU Human Vibration directive, when the daily vibration exposure value exceeds the daily exposure action value, the employer shall institute a program to reduce worker exposure to hand-arm vibration to a minimum and institute worker training and medical surveillance as outlined below. Workers shall not be exposed to vibration above the daily exposure limit value. With regard to ANSI S2.70, when the daily vibration exposure value exceeds the daily exposure action value, it is recommended that the employer institute a program to reduce worker exposure to hand-arm vibration to a minimum and institute worker training and medical surveillance as outlined below. Workers should not be exposed to vibration above the daily exposure limit value.

The permissible vibration total value when the total daily vibration exposure time, T, is different than 8 hours can be written:

The permissible vibration total values for exposure times, T, other than 8 hours that are associated with the EU daily exposure action and limit values are give by:

Daily Exposure Action Value:
Daily Exposure Limit Value:

Figure 3 shows plots of the permissible vibration total values for time periods other than 8 hours that are associated with the 8-hour daily exposure action and limit values. The top curve is the permissible vibration total values associated with the 8-hour daily exposure limit value of 5.0 m/s², and the bottom curve is the permissible vibration total values associated with the 8-hour daily exposure action value of 2.5 m/s². The region between the two curves is referred to as the caution or Health Risk zone. With regard to ANSI S2.70, health risk threshold (beginning of Health Risk Zone) is defined as the dose of hand-transmitted vibration exposure sufficient to produce abnormal signs, symptoms, and laboratory findings in the vascular, bone or joint, neurological, or muscular systems of the hands and arms in some exposed individuals. High health risk (Serious Health Risk Zone) is defined as the dose of hand-transmitted vibration exposure sufficient to produce abnormal signs, symptoms, and laboratory findings in the vascular, bone or joint, neurological, or muscular systems of the hands and arms in a high proportion of exposed individuals.

Figure 3

Vibration Measurements

Vibration measurements on work equipment shall be conducted in accordance to the procedures specified in ISO 5349 Parts 1 and 2. When vibration measurements are conducted:

the methods used may include sampling, which must be representative of the personal exposure of a worker to the hand-arm vibration in question. The vibration transducers and related transducer adaptors used must be compatible with the particular characteristics of the vibration to be measured, to ambient factors, and to the characteristics of the transducers themselves.
on equipment that must be held with two hands, vibration measurements will be made for both hands. The daily vibration exposure values related to both hands will be reported. The daily vibration exposure will be determined by the higher of the two reported daily vibration exposure values.

Obligations of Employers

When workers are exposed to hand-arm vibration, the EU Human Vibration Directive requires employers to determine and assess the risks of their employees to potential health effects related to hand-arm vibration. The potential risk associated with exposure to hand-arm vibration may be assessed by:

Measuring the actual vibration values to which workers are exposed and then calculating the corresponding vibration total values and the related daily exposure values.
Analytically estimating the potential vibration total values and the related daily exposure values based on the observation of work practices and using equipment vibration values that are supplied by equipment manufacturers or other credible sources.

Risk Assessment

When a risk assessment related to worker exposure to hand-arm vibration is conducted, attention must be given to:

the level, type and duration of hand-arm vibration exposure, including any exposure to intermittent or repeated shocks;
the exposure limit values and the exposure action values specified by the EU Human Vibration Directive;
any effects with regard to the health and safety of workers that are particularly at risk;
any indirect effects on worker safety resulting from the interaction between mechanical vibration and the workplace or other work equipment;
information provided by the manufacturers of work equipment in accordance with other appropriate EU directives;
the existence of replacement equipment designed to reduce the levels of hand-arm vibration exposure;
specific working conditions, such as low temperature;
appropriate information that is obtained from health surveillance of workers exposed to hand-arm vibration.

Provisions Aimed at Avoiding or Reducing Hand-Arm Vibration Exposure

When the daily vibration action limit is exceeded, the employer shall establish and implement a program of technical and/or organization measures that are designed to reduce to a minimum the exposure of workers to hand-arm vibration. Particular attention should be given to:

other working methods that require less exposure to hand-arm vibration;
other appropriate work equipment of good ergonomic design, taking into account the work to be done, that produce the least possible vibration;
the use of auxiliary equipment that reduces the risk of injuries caused by vibration, such as handles that reduce the vibration transmitted to the hand-arm system;
appropriate maintenance programs designed to keep equipment that cause vibration in good working order;
the design and layout of workplaces and work stations;
adequate information and training to instruct workers on the proper use of equipment to increase safety and to reduce potential exposure to hand-arm vibration;
limitation of the duration and intensity of hand-arm vibration exposure;
appropriate work schedules with adequate rest periods; and
appropriate clothing to protect workers from exposure to cold and dampness.

Whenever possible, hand-arm vibration levels should be reduced at the source, or at least reduced to a minimum. Personal protective equipment, such as antivibration gloves that meet the requirements of ISO 10819, may be used in conjunction with the procedures specified above to reduce vibration directed into the hand-arm system.

Worker Training

When a risk assessment associated with hand-arm vibration is conducted, the employer shall ensure that workers who are exposed to risks from hand-arm vibration and/or their representatives receive information and training related to the outcome of the risk assessment. The information and training should present information on:

the measures taken to implement the EU Human Vibration Directive in order to eliminate or reduce to a minimum exposure to hand-arm vibration;
the daily exposure action and limit values published in the directive;
the results of the risk assessment study and the potential risk of injury arising from the use of vibrating equipment at work;
why and how to detect and report signs of injury related to hand-arm vibration;
why and how to detect and report signs of injury related to hand-arm vibration;
the circumstances in which workers are entitled to health surveillance; and
safe working practices to minimize exposure to hand-arm vibration.

Health Surveillance

When the results of the risk assessment indicate worker vibration exposure exceed the daily exposure action level, a health surveillance program shall be implemented. Such surveillance shall be appropriate where:

the exposure of workers to hand-arm vibration is such that a link can be established between that exposure and an identifiable or harmful effects on worker health;
it is probable that the illness or the effects related to hand-arm vibration exposure occur in a worker's particular working conditions; and
there are proven techniques for the detection of the illness or the harmful effects on health related to hand-arm vibration exposure.

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