Four assessment tools of ergonomics interventions: case study at an electric utility's warehouse system.

An ergonomics program was developed in a Midwestern electric utility warehouse system. Tasks problematic with respect to work-related musculoskeletal disorders (WMSDs) affecting both the back and upper extremities were identified and engineering controls were implemented. Quantitative analysis was performed on each task before and after ergonomics intervention to evaluate exposure to the risk of WMSDs. Four methods were used to evaluate the risk of exposure to injury before and after ergonomics intervention: the 1991 National Institute for Occupational Safety and Health (NIOSH) lifting equation, the Static Strength Prediction Program, the Lumbar Motion Monitor, and the Borg psychophysical assessment of effort. Results from applying these four methods to the reengineered tasks showed that the probability of low-back disorder risk factors was reduced by as much as 29%, the percentage of people capable of performing tasks was increased by as much as 90%, the NIOSH Lifting Index was reduced from above 2.0 to less than 2.0, and the psychophysical assessment of effort was consistently reduced from the "heavy or strong" range to the "light or moderate" range.