A model of combine exposure to whole-body and hand-arm mechanical vibrations in the working environment

The main aim of the project was to develop a model of a comprehensive assessment of workers' exposure to simultaneous whole-body and hand-arm mechanical vibrations. A methodology of investigating whole-body and hand-arm vibrations present at the same time in the working environment was developed within this project. It is based on simultaneous recording of acceleration signals of hand-arm and whole-body vibrations. A methodology of studying the reaction of a worker's body to whole-body and hand-arm vibrations was also developed. Field studies were prepared at selected real workstations (based on the registration of signals of whole-body and hand-arm vibrations) and laboratory tests at special test stands for determining the reaction of the subject to various combinations of vibrations. Considering maximum admissible intensities and the requirements of Standard PN-EN ISO 13090, the kind of simulation exciting vibration signals was determined as well as the value and duration of exposure. Criteria for selecting subjects were developed as were the characteristics of the vibrotactile perception threshold tests; after consultations they were accepted as basic tests. A laboratory test stand was developed for testing whole-body vibrations; it makes it possible to simulate exposure to vibrations acting on a sitting person. A test was also developed for testing exposure to hand-arm vibrations.The test results confirmed that using the proposed method of assessing simultaneous exposure to hand-arm and whole-body vibrations, which is based on summing the energy (in the proposed model, doses proportional to the energy) at workstations where both types of vibrations are present is well-founded.