Load and capacity behavioral aspects of job safety are discussed in relation to a conceptual model on accident causation. A large proportion of accidents are seen as stemming from one or more initiating incidents, all involving human action or inaction. Factors leading to such incidents are grouped into three categories: improper activities and procedures (unsafe practices conducted without knowledge or awareness of the potential consequences); incompatibility (a factor which exists when the dissimilarity or disparity between human and equipment or task characteristics are such that safe performance is jeopardized); and overload (a factor which becomes apparent when the task load momentarily or chronically exceeds the work capacity of the individual). When overload occurs, the worker selects from a limited number of possible compensating behaviors in an attempt to deal with the work overload. All compensating behaviors are assumed to compromise performance and create initiating incidents. Influences on worker capacity are listed as natural endowment, physical condition, fatigue, drugs, pollutants, and environmental stresses, training, motivation, and arousal. The author recommends that improvements in industrial safety include proper worker and task compatibility, training, minimization of adverse environmental load factors, and fail safe task design.
Occupational Safety and Health Symposia 1978, Division of Technical Services, NIOSH, Cincinnati, Ohio