Explain the segmental vibrations with different examples and physiological effects?This question is related with ergonomics topics Whole body Vibrations
Vibrations affecting people working on various types of industrial environments and work are classified in two broad types, whole body vibrations and segmental body vibrations. The whole body vibrations affect the body of the operator. I contrast segmental vibrations affect some specific segments of the body such as hands and arms, or foot and legs. An example of full body vibration is a person driving a truck. An example of segmental vibration is the impact of pneumatic drill, which primarily transmits its vibration to hand and arms of operator.
Segmental vibrations can relate to any part of the body, but mostly often part of the body affected by vibrations are arms and the body. These vibrations cause several damage to the affected body parts. Most common problems of segmental vibrations are Reynaud's decease, also called white finger disease, and Dart's disease.
In Reynaud's decease involves constriction of muscles of blood vessels in hands and fingers leading to white fingers caused by a reduction in blood flow to the hand and fingers. It then leads to permanent damage to nerves and blood vessels in the hand.
Dart's disease symptoms are opposite to those of white finger disease. Blood collects in the hand which then become blue, swollen and painful.
The hand-tools which , during the operation, cause vibrations, are the factor which triggers Reynaud's disease and Dart's disease.
In the Reynaud's disease, which is also known as the disease of white fingers, nerves and blood vessels from the hand that operating the vibrating tool, are injuried permanently. The symptoms are the loss of muscle control of the injuried hand, the affected person presenting difficulties in manipulating things. The feeling is similar with hand numbness while sleeping (pains, numb, tickles).
Dart's disease is not so common as Reynaud's disease and the level of vibrations which can produce it is higher than the frequency of 100Hz.Effects of the disease are opposite to Reynaud's syndrome, where the blood flow was interrrupted and the hands became white. In this case, the blood floods the hands which are becoming painful and blue.
There are some guidelines in order to help designing of such as hand tools which are working and producing vibrations, these guidelines having the aim to reduce the undesirable effects of using vibrating handtools.