Assessment and design of industrial manual handling to reduce physical ergonomics hazards – use and development of assessment tools

Despite efforts of reducing harmful physical ergonomics exposures related to manual handling operations, the occurrence of hazardous exposures such as heavy or repetitive manual handling, non-neutral postures and hand-arm and whole-body vibrations is high in many occupational sectors. These physical ergonomics exposures are considered to substantially contribute to a large proportion of work related musculoskeletal disorders and occupational diseases in many industrial sectors such as the manufacturing industry. To reduce these harmful exposures (risk factors), interventions and job design strategies can utilize risk assessment, which is also a requirement for jobs involving manual handling operations or hazardous exposures. Despite several observation-based tools to support risk assessment of manual handling jobs, a need was identified of an observation-based tool which supported occupational health and safety practitioners with detailed assessments of a broad range of risk factors related to manual handling and which supported each step in a systematic work environment management. The aim of this thesis was to explore the use and important usability-related aspects of observation-based assessment tools among professional ergonomists employed in Sweden. Furthermore, to develop new research based assessment and screening tools, to present their scientific basis and to evaluate their reliability and usability. A web-based questionnaire was employed to gain knowledge on the use of risk assessment tools among professional ergonomists in Sweden and which usability-related aspects they considered important of such tools. To develop the new assessment tools (i.e. RAMP I and RAMP II), literature searches were performed to identify quantitatively described risk factors related to manual handling and important task parameters affecting the workers capacity in manual handling. The tools were developed in an iterative process with input from more than 80 practitioners, including more than 30 ergonomists, and with expert group judgments. The two tools were evaluated concerning their inter-rater reliability using assessment made by professional ergonomists and engineers of videotaped industrial manual handling jobs. A paper-based questionnaire was employed to evaluate the tools usability among 20 occupational health and safety practitioners, and the ease of use of the parts of RAMP II among 22 professional ergonomists. The thesis points to a low proportional use of several internationally spread assessment tools among professional ergonomists in Sweden, and a relatively higher use of tools promoted by the Swedish Work Environment Authority. Several usability-related aspects for assessment tool were identified as important for this population. In particular, these aspects were related to the tools being easy and quick to use, the tools’ ability to communicate and visualize the results, and the tools’ ability to facilitate improvement measures. The developed screening and assessment tools support assessment of a broad range of risk factors related to industrial manual handling. The thesis supports that assessments with acceptable reliability can be achieved for the majority of items of the two developed tools, and improvement areas have been identified. The thesis supports that the two developed tools are usable in supporting risk assessments targeting musculoskeletal disorder risk factors related to industrial manual handling.