Can humans control vibrations?

Vibration protection: Avoid health hazards in the company

Health hazards in the workplace have many causes. Obvious are always the dangers that act abruptly and quickly and are therefore perceived immediately. But even supposedly gentle effects can cause damage to health in the long term. These less objective hazards also include oscillations and vibrations, which can cause severe damage to and in our bodies. That is why the legislator obliges to take extensive vibration protection measures.

Vibrations and oscillations that arise during the work process in the company have medically relevant consequences for the employees of a company. Vibration triggers general discomfort, headaches and shortness of breath. It is not uncommon for employees to complain of speech and vision disorders, damage to the muscles and impairment of the digestive tract.

These symptoms are often related to vibrations in the workplace. In order to ensure health protection for employees, employers and companies must avoid health hazards from vibrations or reduce them to a minimum.

Whole body and hand-arm vibrations

Vibrations are again differentiated into whole-body and hand-arm vibrations.

Whole body vibrations

With this form of vibration, the vibrations affect standing or sitting people. The causes of

Whole body vibrations are mechanical vibrations. These are transmitted from machines or vehicles at the workplace via the seat or the feet. Whole-body vibrations occur, for example, in vehicles, airplanes or on ships. In addition, the vibrations occur on mobile work equipment such as excavators or drive machines.

Whole-body vibrations have a significant impact on the human body. On the one hand, they can influence performance. On the other hand, the vibrations have a negative effect on general well-being.

In addition, whole-body vibrations can damage the spine. The Federal Institute for Occupational Safety and Health (BAuA) provides a free information sheet on this occupational disease on its website.

Section 9 of the Noise and Vibration Occupational Safety and Health Ordinance (LärmVibrationsArbSchV) specifies the exposure limit values ​​and trigger values ​​for whole-body vibrations.

The exposure limit is:

A (8) = 1.15 m / s2 in (horizontal) X and Y directions

A (8) = 0.80 m / s2 in the (vertical) Z-direction

The trigger value for whole-body vibrations is A (8) = 0.50 m / s2 (for all directions)

The exposure and action value relates to an 8-hour working day.

Note: The exposure limit value defines the maximum value that the employee may be exposed to on the working day. If the action levels are exceeded, employers must take measures to prevent and reduce noise and vibration. Young people, such as apprentices and nursing mothers, must not be engaged in work in which the safety and health is impaired by vibrations.

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Hand-arm vibrations

In most cases, the vibrations are transmitted to the hand-arm system by the tools. The vibrations cause bone and joint damage, circulatory disorders and neurological diseases. Hand-arm vibrations are mainly caused by working with vibrating hand machines, such as working with grinding devices, chisel hammers or power chain saws.

The exposure limit values ​​and the action values ​​are also laid down in § 9 LärmVibrationsArbSchV.

The exposure limit is:

A (8) = 5 m / s2

The trigger value is as follows: A (8) = 2.50 m / s2

Here, too, the exposure limit value and the action value relate to an 8-hour working day.

Activities with hand-arm vibrations that are carried out over a long period of time can lead to various occupational diseases.

These are:

  • BK 2103: "Illness due to vibration when working with compressed air tools or similarly acting tools or machines"
  • BK 2104 "Vibration-related circulatory disorders in the hands"

* The abbreviation BK stands for occupational disease

Health impairments due to vibrations

the fact is: Similar to noise, vibrations have a number of different influencing factors on health.

The stress on the body and health results from various factors:

  • Strength of the vibrations
  • Frequency of vibrations
  • Duration of exposure to the vibrations
  • general way of working
  • activities

The following diseases are specifically caused by vibrations. Hand-arm vibrations and whole-body vibrations are distinguished again:

Whole body vibrations

Whole-body vibrations are often associated with balance disorders and so-called sea and air sickness. In addition, the vibrations are often responsible for impaired vision and impair fine motor coordination and physical performance. For some employees, whole-body vibrations also cause stomach problems and diseases of the spine.

Hand-arm vibrations

Long-term vibration exposure in the higher frequency range can lead to circulatory disorders in the fingers. The consequences are deafness or what is known as Weißfinger's disease. In the low-frequency range, degenerative changes in the hand bones as well as damage to the joints in the hand, the elbow and the shoulders are to be expected.

This is accompanied by pain and restricted mobility. In addition, fatigue fractures are possible. At low temperatures, the risk of these complaints increases.

Vibration protection: risk assessment

If employers know which vibrations cause damage, they can effectively avoid them. In order to record and evaluate dangers in the company, employers must carry out a risk assessment for every workplace. According to Section 5 of the Occupational Safety and Health Act (ArbSchG), they are obliged to do so. As part of the risk assessment, the vibration values ​​are measured for each workplace.

To carry out the risk assessment, measuring methods and devices are used to determine the existing workplace, exposure and action values. In addition, the procedures and devices are used to check the values ​​and whether they are being observed. The measurements are sometimes also carried out on a random basis. As part of the risk assessment, the employer must document the results.

Note: There is a 30 year retention period for the measurement results. A later inspection of the measurement results must be possible at any time.

Calculate daily vibrations at the workplace

The risk assessment is in turn stipulated in the Noise and Vibration Occupational Safety and Health Ordinance Employers must record possible dangers for both hand-arm vibrations and whole-body vibrations.

If the vibration effect of the machine used and the associated exposure times are known, the daily vibration can be calculated. The Institute for Occupational Safety and Health of the German Social Accident Insurance (IFA) provides a free computer for this on its website.

In addition, the IFA provides a checklist for risk assessment.

Measurements for whole-body vibrations

Whole-body vibration measurements are usually carried out directly on the driver's seat of the vehicle to be measured or on the vibrating surface. A triaxial accelerometer measuring cushion is used for this, which is mounted on the seat and fixed with adhesive tape.

All three spatial directions are taken into account in this measurement. Therefore it must be on the correct alignment of the measuring pad

  • x = chest-back direction,
  • y = shoulder-shoulder direction,
  • z = direction of the spine / vertical

and the correct weight setting on the driver's seat must be ensured.

The measurement duration takes into account the distance to be traveled during the work process. This should be at least 15 minutes. Measurements are always carried out during normal operation and include any existing boundary conditions such as loads or loads.

The largest effective value of the frequency-weighted acceleration in the three measuring directions is used to assess the whole-body vibrations. The acceleration values ​​in the horizontal directions (x and y direction) must be multiplied by a correction factor of 1.4 in advance. The conversion to the daily vibration exposure value is then carried out taking into account the actual effective exposure duration.

Calculations of exposure values ​​can be simplified by using the characteristic value calculator from the Internet. These exposure calculators also calculate the mean value and present some of the results clearly in the form of a traffic light model: Results below the trigger values ​​are marked in green, results above the limit values ​​are in the red area.

Determination of the risk of whole-body vibrations

To determine and evaluate the hazards of whole-body vibrations, employers proceed as follows:

  1. Check the lanes in operation (factory premises or factory halls) and eliminate potholes and breakouts. The vibration load is reduced and accidents are prevented by flat roadways.
  2. Pay attention to low vibration values ​​when purchasing new vehicles.
  3. Work processes should be organized in such a way that effective driving times (exposure times) can be achieved.
  4. Pay attention to employees who work in relevant vehicles. Employers should regularly check the seated position of employees.
  5. Employees should avoid a twisted posture. If possible, anti-vibration seats should be fitted to the vehicles, correctly adjusted and serviced at regular intervals.
Note: The daily vibration exposure should not exceed the value A (8) = 0.5 m / s2.

After the hazard assessment of whole-body vibrations, employers must inform employees about the hazards as well as the trigger and limit values. Companies should offer regular preventive examinations in the event of regular vibration exposure.

Carrying out measurements of hand-arm vibrations

Hand-arm measurements are always carried out on the handles of the machine. A triaxial accelerometer is attached to the handle with a clamp or collar and serves as a measuring device.

For the assessment of hand-arm vibrations, the total vibration value (ahv) determined from the frequency-weighted accelerations of all three vibration directions. Companies and employers must ensure that the typical work process for the workplace is always measured.

Determination of the risk of hand-arm vibrations

  1. For every workplace it must be checked whether hand-held and hand-guided work equipment and tools that put stress on the joints can be replaced. During this test, high-speed work equipment and tools with frequencies of 20 to 100 Hz must be given special attention, as they lead to high stress on the hands.
  2. Check work equipment whether it is equipped with handles, damping and cushioning. When purchasing new equipment, employers must ensure that they have a low vibration level. As a rule, the tool manufacturers provide information on this value and advise their customers on it.
  3. Review of organizational options, such as process changes to eliminate or reduce high exposures. Above all, employers have to pay attention to high gripping and pressing forces. These can be avoided through suitable working methods or technical aids. Employees should wear special vibration protection gloves, especially when working outdoors or in cold weather.

General risk assessment in seven steps

  1. Recognition of potential hazards in the workplace
  2. Summary of individual groups of employees with comparable activities
  3. Determination of the daily exposure value A (8)
  4. Assessment of the hazard
    4.1 Is the exposure limit exceeded?
    4.2 Has the trigger value been exceeded?
    4.3 Has the trigger value been reached?
    4.4 Is the trigger value undershot?
  5. Implementation of vibration measurements
  6. documentation
  7. Control and renewed risk assessment
Note: The risk assessment is the first and safest step in the inventory and assessment of hazards caused by vibrations in operation. In a second step, the program of measures for vibration protection will be developed.

Exposures that occur can only be identified and reduced at an early stage with a risk assessment.

In order to fully include all hazards, the assessment should be carried out as follows:

  • job-related
  • machine-related
  • job-related
  • personal

Risk assessment is based on either empirical values ​​or specific measurements, which can usually only be carried out with specific specialist knowledge and expensive measuring devices.

However, companies do not have to identify hazards individually. In most cases, typical vibration loads can be taken from catalogs, (online) databases or from manufacturer information such as operating instructions without a great deal of measurement effort.

Information from accident insurance carriers or supervisory authorities also helps to assess which work activities and workplaces involve high levels of vibration and are therefore to be assessed as dangerous.

In practice, manufacturer information is the easiest available basis for risk assessment. Because with the EC Machinery Directive, the manufacturers of machines are obliged to provide specific information on the vibrations that occur on the machines.

Vibration risk assessment

In addition to the risk assessment, companies and employers must carry out a risk assessment. This determines the health risk for employees from whole-body and hand-arm vibrations.

For an assessment and evaluation of the overall health risk, however, additional influencing factors must be taken into account in individual cases:

  • Unfavorable working conditions such as an unnatural work posture or outdated work equipment can lead to increased exposure.
  • Higher gripping and pressing forces increase the exposure.
  • Cold influences. They have an unfavorable effect on the exposure effect.

Characteristic values ​​for the effect of these influences can also be taken from the existing online databases. One example is the KarLa database of the Brandenburg State Office for Occupational Safety and Health.

The purpose and result of the risk assessment is to assess whether there is such a major health risk that further measures must be taken to protect employees. The limit values ​​for this are given in the following table:

Development of an action plan

If the exposure and action values ​​are exceeded, employers must take technical and organizational measures to protect employees from the exposure to vibrations and to reduce health hazards.

Examples of suitable measures are:

  • Alternative working methods
  • Exchange of work equipment
  • Limitation of the duration and intensity of the exposures

Protective measures according to the stop system

The measures for vibration protection should be based on the so-called Stop system be planned.

S - Substitution: Measures that change the work process in such a way that there are no harmful vibrations.

T - Technical solutions: retrofitting or replacement of machines, tools and vehicles

O - Organizational measures: Vibration-intensive activities should be limited in time. For example, you can set maximum working hours for the employees concerned at the workplace.

P - Personal protective measures: If no other measures are possible, it is the turn of the personal protective measures. However, they are only suitable for hand-arm vibrations with higher frequency vibration components. These measures include, for example, the provision of personal protective gloves.

Additional measures

  • Occupational medical check-up for employees.
  • Documentation of all measures for vibration protection. This also includes the employee briefing including the signatures of the workforce.
  • Regular review of the measures for their effectiveness.
Note: Instructions for action for preventive measures to protect employees from exposure to vibrations are provided by the employers' liability insurance association and the accident insurance institutions.

Primary measures for vibration protection

The primary measures are all measures that reduce the vibrations at the source. Primary measures also reduce all other negative effects of the vibrations. Low-vibration technology is often used in the area of ​​hand-arm vibrations.

Here, employers must pay attention to the following points, among other things:

  • Use of press riveting tools for the production of riveted joints
  • Use of torque wrenches instead of impact wrenches to assemble screw connections
  • Use of rotary hammers compared to impact drills
  • Use of vibration-damped impact and demolition hammers in road construction and mining
  • Use of chisel hammers with vibration-damping grip sleeves for working stone and steel
  • Use of chain saws with vibration-damped handles in forestry
  • regular sharpening of tools
  • regular balancing of tools and machines
  • Use of adhesives instead of rivets

In the case of whole-body vibrations, there are three areas in which measures must be taken to protect against vibrations.

Removal of road impurities

Here companies must pay attention to the following:

  • Straightening unpaved roads and construction sites
  • Inspection of factory roads and gate entrances
  • Avoidance of thresholds and transverse grooves
  • Mending damage such as potholes

Elimination of vibrations

This is about reducing vibrations in rail and crane vehicles. Connection points of rails must be welded well and joints must be regularly repaired. These primary actions require regular inspection and maintenance of the rails.

Use of suitable technologies

Here employers can equip driver's or driver's cabs with spring-loaded seats. In addition, companies should point out to their employees that every driver must adjust the seat to their own body weight.

Excessive travel and the use of rubber dampers at the top and bottom of the travel. Axle suspensions should be equipped with hydraulics and level controls.

Secondary measures for vibration protection

These are measures that help reduce the transmission and spread of vibrations. Secondary vibration protection measures can also help reduce vibrations.

In the area of ​​whole-body vibrations, secondary measures must be taken to isolate machines or workplaces from vibrations, for example using vibration foundations or vibration isolators. In addition, the machine must be decoupled from building or other machine parts.

Note: Secondary measures are not applied in the case of hand-arm vibrations.

Organizational measures for whole-body and hand-arm vibrations

The risk of vibration can also be reduced by reducing the exposure time by changing the work organization.

Valid for both forms of vibration

  • Rotation of employees when working with hazardous equipment in order to reduce the exposure time of each individual employee
  • Planning longer breaks and thus reducing dangerous working hours

Personal protection against hand-arm vibrations

If no other measures are considered, the vibration exposure can be reduced through personal protective measures.

The change in behavior of the affected employee can improve with hand-arm vibration through regular training of an appropriate posture under medical supervision. This is the only way to ensure that the holding and pressing forces are reduced when using devices.

In addition, employers must provide employees with personal protective equipment in the form of vibration protection gloves in the event of high-frequency vibrations. Gloves should be worn on grinding machines.

Note: Personal protective measures are not considered in the case of whole-body vibrations.

Author: Editorial Team Safety Xperts