| Summary: | Hand-arm vibration syndrome because of working with hand-held vibrating machines, is increasing in the work environment and have in the last decade contributed to an increasing number of people with irreversible injuries. Risk assessment is legally required by the employer and an important part of the risk assessment is to calculate the daily vibration dose, A(8), for the workers. Knowledge of the validity of different methods for measuring the daily vibration dose A(8) and exposure time of hand-held vibrating machines is lacking. To investigate the validity of different methods, a field study was performed on 12 construction workers, at a construction site in Northern Sweden. Measurement methods included were: self-assessment questionnaire, field observation and a vibration clock. The study showed descriptively and visually indications, and statistically significant differences between all measurement methods. Compared to observation (golden standard), the self-assessment questionnaire overestimated vibration dose A(8) and exposure time. As a result of the overestimation in the self-assessment questionnaire for exposure time, more participants exceeding both input and limit value for vibration dose A(8). The vibration clock agreed better on average to observation than self-assessment questionnaire, with fewer participants above the input value and none above the limit value. Over- or underestimation of A(8) can result in uncertainties of a risk assessment according to AFS 2005:15 of hand-arm vibration. Increased use of observation may increase the risk of injuries being misjudged, since today´s input and limit value are based self-assessments. Further studies of the validity of different methods are therefore necessary.
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