Vibrations are rapid back and forth movements of objects.People at work frequently subjected to different types of vibrations that interfere with their work, affect the rate of becoming fatigued and also cause short and long term health problems. Vibrations are very obvious in some equipments such as pneumatic drill used in drilling holes in rocks, or in all kinds of reciprocating equipments. But vibrations of different magnitudes are present in almost every mechanically driven equipment.
Vibrations may affect whole body of an operator or some specific part of the body such as hands and arms.
Vibrations are classifies according to different characteristics. For example:
- Sinusoidal versus random vibrations.
- Direction of vibrations relative to the human body. For example head tail vibration and fore-aft vibration.
- Frequency of vibration.
- Intensity of vibration.
Vibrations affect the performance of the operator by interfering with visual and motor functions of the body. Vibrations also cause a subjective feeling of discomfort and induce fatigue.
Short term exposure to vibrations causes minor physiological effects. This may include increasing in breathing and heart rate and increase in muscle tension., which may be in anticipation of stress conditions. However prolonged exposure to high intensity whole body vibrations has many adverse effect on health. There is an increased risk of spinal and nervous system problems. The digestive system, peripheral veins, female productive organs, and vestibular system may also be affected.
Vibration are effects on human body which are caused by direct contact with work equipment, contact which produces oscillations or collisions (chain saws, pneumatic hammers, etc.).
Vibration at work
Vibrations are present in most environments where mechanical equipment is used.
Types of vibration
• whole-body vibration (produced by excavators, trucks, bulldozers, cars, etc. level.)
• hand-arm vibration (grinding machines, cutting wood, chain saws, hand saws, axes, drilling machines, etc..) Occupations in which the body is affected by vibrations
• Working with chain saws • Construction worker and driller • Automotive Industry and repair tools manufacturers • Welders • Pipeline Construction • Roads and railways • Quarries In assessing the vibrations are taken into account the following aspects:
• Level of vibration, acceleration, frequency, pulse
• Duration, continuity
• vibration radiation (weight gear, power clamping device, hand position, area of exposure)
• Clothing In the absence of appropriate measures is difficult to estimate the level of vibration produced by gear
• Obligations of manufacturers of tools and employers on the measurement of vibration, protection of workers and information concerning the minimum safety and health relating to exposure of workers to risks arising from vibration:
-Daily exposure limit value (8 h) 5 m/s2
-Action-value limit of exp. daily (8 h) 2.5 m/s2
The effects of vibration
• more rapid depletion
• lack of concentration
• worsening vision
• musculoskeletal disorders-in particular problems of the spine
• blood circulation disorders, especially the fingers. Prevention effects of vibration on human body
Smoking and low temperatures are negative effects to be added vibration. • Lowering the minimum exposure
-Improving technical gear
-Minimum exposure time
• Knowledge about the level of vibrations emitted by the new tools used
• Stop smoking
• Periodic medical examinations