The Influence of Lifting Horizontal Distance Measurement Error on NIOSH Lifting Equation Assessment Outcomes

Low back injuries are becoming increasingly costly due to the compensation costs and lost days of work. Most of these injuries are linked to manual material handling (MMH) activities. Several ergonomic assessment methods are available to assess the risk factors and determine the risk level for a given MMH job. The National Institute for Occupational Safety and Health (NIOSH) Lifting Equation is the most popular and frequently used ergonomic assessment method to assess MMH jobs. The load weight and horizontal distance are the most significant low back pain risk factors in such jobs. Errors in the measurements of load horizontal distance may influence the risk level obtained from the NIOSH Lifting Equation assessment method depending on the weight of the load being handled. Measurements of the horizontal distance variable measured by novice college students were used to examine NIOSH Lifting Equation sensitivity to the horizontal distance measurement errors with respect to the load weight. The results showed that even though errors in the horizontal distance measurements influenced the resulted lifting index values, that did not influence the resulting NIOSH Lifting Equation risk assessment outcomes for almost all lifting conditions.