Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)


Engineering Science (Interdepartmental Program)

First Advisor

Fereydoun Aghazadeh


The objectives of this research were to determine the most important risk factors in VDT workstations associated with physical symptoms and to investigate the interrelationship among these risk factors. A conceptual model was first developed to describe the interrelationship among the basic components in a VDT workstation system and their possible health effects. A research model was then proposed to describe the hypothesized relationships among the following categories of variables: demographic, task, workstation design, work environment, psychosocial factors, work posture, psychological stress, musculoskeletal symptoms, visual symptoms, and general physical symptoms. A method which consisted of a questionnaire, measurement and posture analysis was then developed. A field study was conducted among daily computer users in a local industry. Ninety three VDT operators participated in the study. Factor analysis was applied to the physical symptoms to help identify the underlying factors. Multiple regression was used to determine the most important factors related to the physical symptoms and the effect of interactions among the risk factors. The four factors identified among physical symptoms are: ocular discomfort, general musculoskeletal symptoms, upper extremity symptoms, and other physical symptoms. Ocular discomfort is significantly related to screen glare; both general musculoskeletal symptoms and other physical symptoms are related to fatigue; and upper extremity symptoms are related to awkward upper body posture. Many interactions between the risk factors and their effects are identified, such as, psychosocial factors and demographic, and workstation factors and working posture. Psychosocial factors are found to interact with other variables and contribute to psychological stress. The implication of this research is that both physical and social environment need to be evaluated and the interactions among the components of a VDT workstation system need to be understood in order to determine physical symptom risk factors.