Using Process Control Concepts to Model Conditions Required for Sudden-Onset Occupational Injuries

Abstract

Sudden-onset injury results from a momentary energy exchange between an agent and host, producing immediately discernible tissue damage. These injuries are common in both occupational and nonoccupational settings; typical causes include falls, mechanical contact/crushing, exposure to temperature extremes, and exposure to electrical current. We review epidemiologic and engineering approaches to injury prevention and propose a process control model for describing risk-of-exposure to injury agents during the Pre-event phase of sudden-onset injury. Process control is a proactive approach to quality engineering that is based on the premise of preventing defective products from being manufactured in the first place, instead of relying on reactive inspections to detect defects at the end of the manufacturing process. Principles of process control can be applied by occupational health and safety professionals to prevent workplace injury. The proposed model describes how work activities (process inputs) cause risk-of-exposure to injury agents to fluctuate over the course of a work shift. Risk-of-exposure is a complex function with many input factors including: the nature/magnitude of hazards, the presence and effectiveness of engineering controls, safety climate, management attitudes and practices, the surrounding work environment, the physical and mental states of the worker, and the quality and quantity of supervision and training. Injury can occur only when this function crosses a certain threshold and the host is exposed to injurious energy via physical contact. Certain factors that contribute to risk-of-exposure are stable for extended time periods (weeks, months, years), whereas other factors are transient (durations of minutes or seconds). The model extends classical work by Haddon and others, provides preliminary insights to designing epidemiologic studies and developing fault-tolerant work systems, and illustrates how interdisciplinary approaches can improve our understanding of the etiology of sudden-onset injuries and advancing injury research.

Keywords:

• epidemiology
• energy transfer
• occupational injury
• process control
• safety engineering

ACKNOWLEDGMENTS

The authors would like to acknowledge assistance from Ragnar Andersson, Theodore Courtney, David Lombardi, Glenn Pransky, and Gary Sorock who provided helpful comments. Dr. Keyserling was supported by the Liberty Mutual Visiting Scholars Program.