| There is a growing evidence that the domain of work demands (e.g., physical demands, mental demands) as characterized through work factors (e.g., weight of load, frequency, horizontal distance, height of lift, work duration, and twisting angle for physical lifting demands) can interact to precipitate hazardous conditions which may potentially result in injuries and illnesses. Research efforts to date have largely focused upon one or a few aspects of the domain of work demands with reference to human effort and injury/illness risk assessment. The synergistic effects of the entire set of work demands on risk outcome measures have also been ignored. The objective of this dissertation is to develop a foundation for a comprehensive work system model, therefore enabling occupational health and safety professionals to understand and evaluate how the complete spectrum of work demands (i.e., physical and mental demands, physical environment and non-physical environment) interact to influence human effort, become hazards, and affect perceived and actual risk.; The dissertation is presented through five parts to describe the work demands classification hierarchy. A review of the scientific literature in each component area found no work analysis instrument adequate to characterize the respective demands for the purpose of hazard and risk assessment in an industrial application.; Part I, the overview, provides the Basic and Expanded Work System Models and descriptions of their components and relationships. Part II characterizes the physical demands component, the domain of complex muscular work. Part III characterizes mental workload which has recently been recognized as playing a significant role in the determination of job performance. Part IV characterizes the non-physical environment (e.g., role in organization, job characteristics) and the home-work interface factors that impact worker performance. The Integrative Work System Model introduced in Part I is updated to include the effects of culture and the home-work interface. Part V details the physical work environment demands which include physical working conditions (e.g., noise, illumination) and work hazards (e.g., fire, mechanical, chemical). For physical and mental demands, checklist and sequence model approaches to evaluation are detailed. For non-physical and physical environment demands, checklists are provided. |
