Vibration - Occupational Risk Prevention

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Definitions and effects of vibrations on health

Many workers are exposed to vibrations in their workplaces, caused by tools and machines or by vehicles such as grinding machine, Jackhammer or driving etc.

Vibration transmitted to the hand-arm system is the mechanical vibration, when transmitted to the human hand and arm system, poses risks to the health and safety of workers, in particular, vascular, bone or joint problems, nervous or muscular. For example, a worker using a grinder machine would be exposed to Hand-arm vibration (HAVS).

Whole-body vibration is mechanical vibration, when transmitted to the entire body, carries risks to the health and safety of workers, in particular low back pain and spinal cord injuries. For example, a truck driver would be exposed to whole-body vibration.

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The effects that they can cause in the body of an exposed person depends on their frequency and if they act on the whole body or on the hand-arm system:

Very low-frequency vibrations (less than 1 Hz) that affect the whole body can cause loss of balance, dizziness or vomiting, such as those caused by the transport.

Vibrations of frequencies between 1 and 80 Hz that affect the whole body can cause low back pain, hernias, impingement discs and spinal injuries, as well as neurological symptoms such as difficulty in maintaining balance. They can be observed, for example, in the workplace vehicle drivers.

Vibrations of frequencies between 20 and 1,500 Hz are typical of rotary or alternative hand tools and their effects are concentrated in the hand-arm system. They can cause bone lesions of the wrist and elbow and alterations in the nerves of the hand that can cause cramps or disturbances of sensation. One of its possible manifestations is the white finger.

Vibration exposure standard:

The daily exposure limit value is:

vibration magnitude measure in m.s² and duration of exposure in hours and minutes 

5.0 m.s² A(8) for hand-arm vibration

115 m.s² A(8) for hand-arm vibration

The effects of Vibration

Effect of vibration
Vibration frequency	Origin of vibrations (machine, tool, vehicle, etc.)	Effects on the body	Vibration frequency
Very low frequency <1 Hz	Transportation: plane, car, boat, floating platforms, train (swinging).	They stimulate the labyrinth of the left ear. They can cause dizziness and vomiting (a bad characteristic of transport). They cause disorders in the central nervous system.	Very low frequency <1 Hz
Low Frequency 1-20 Hz	Transport vehicles for passengers and/or goods. Tractors and agricultural machinery. Industrial vehicles, forklifts, elevators, etc. Earthmoving machinery and vehicles (excavators, bulldozers, etc.) Forestry, mining and quarrying machinery.	Low back pain, hernias, disk impingement. Neurological symptoms: variation in brain rhythm, difficulty in balance. Resonance vision disorders. They aggravate minor spinal injuries and affect disorders typical of poor posture.	Low Frequency 1-20 Hz
High-frequency 20-1000HZ	Rotary, alternative or percussive hand power tools such as polishers, sanders, grinders, chainsaws, pneumatic hammers, choppers, breakers and perforators. Equipment with vibrating parts: column grinding, lawnmowers, road compactors.	Osteo-articular disorders detectable radiologically: Hyper-supporting osteoarthritis of the elbow. Wrist injuries Angino-neurotic conditions: Increased incidence of stomach diseases. Angioneurotic conditions of the hand such as cramps.	High-frequency 20-1000HZ

Vibration characteristics

To define the exposure to vibration to which a person is subjected, the exposure time must be taken into account. Vibration consists of the movement of a solid body around its equilibrium position without there being a net displacement of the vibrating object.

Classification of vibrations

Vibrations are defined by their intensity and by their frequency.

In occupational risk prevention, two differentiated vibration models are studied:

• Whole-body vibrations, which occur when much of the human body's weight rests on a vibrating surface and is generally transmitted through the seats or feet.

• Vibrations transmitted to the hand-arm system, which are transmitted by the worker's hands generally through the grip of mechanical tools and usually affect the hand-arm system.

Whole-body vibrations are, for example, those transmitted by vehicle or machine seats or the vibration of a platform or floor. The vibrations of the hand-arm system are, for example, those transmitted by hand tools, such as drills or grinders, or by elements of the work equipment that are held with the hands, such as the control levers or the steering wheel of a vehicle.

Control measures

Taking into account technical advances and the availability of risk control measures at their source, the risks arising from exposure to mechanical vibrations should be eliminated at their source or reduced to the lowest possible level by taking into account:

• Other working methods.

• Choosing the right work team.

• The provision of auxiliary equipment reduces the risks of injury from vibrations.

• Appropriate maintenance programs for work equipment, workplace and workstations.

• The conception and arrangement of places and jobs.

• Adequate information and training for workers on the correct and safe handling of work equipment, in order to minimize exposure to mechanical vibrations.

• The limitation of the duration and intensity of the exposure.

• Proper organization of working time.

• The application of the necessary measures to protect exposed workers from cold and humidity, including the provision of adequate clothing.

• Regarding personal  protective equipment against vibration transmitted to the hand-arm system, they  can contribute to the program of technical and/or organizational measures aimed at minimizing exposure to mechanical vibrations and the risks derived from it.

Personal protection equipment against vibrations is very scarce and its effectiveness has not been fully demonstrated. Thus, anti-vibration gloves, the use of which can help to avoid the damaging effects of vibrations, but should always be considered as a complementary element within technical measures.

In the case of exposure to hand-arm vibrations in cold environments, the use of gloves is recommended to keep hands warm, since low temperatures are one of the factors that can contribute to the appearance of white finger syndrome.

The employer will ensure that workers exposed to risks derived from mechanical vibrations in the workplace and/or their representatives receive information and training regarding the result of the risk assessment, in particular on:

Measures are taken to eliminate or minimize the risks derived from mechanical vibration.

• Exposure limit values ​​​​that lead to action.

• Convenience and way of detecting and reporting signs of damage to health.

• Circumstances in which workers have the right to have their health monitored.

• Safe work practices, to minimize exposure to mechanical vibrations