Elements of Ergonomics Programs A Primer Based on Workplace Evaluations of Musculoskeletal Disorders

NIOSH staff conducted an ergonomic study of soft beverage driver-sales jobs. Such job tasks as handling beverage cases for delivery were problematic for two reasons: the stacking of cases in the truck bay exceeded the normal reach limit of workers, and most of the beverage lifting tasks also exceeded the recommended weight limit of the 1993 NIOSH lifting equation. Heart rate measurements, as an indicator of the physical effort required for this work, were found to be high among the driver-sales workers, especially during peak periods. Estimates indicate that more than 35,000 lb of beverage products were handled daily by these driver-sales workers. The rate of musculoskeletal injuries for the affected workforce, in terms of days lost, was twice that of workers in general manufacturing jobs.

To relieve the above-mentioned problems, the following engineering controls were implemented:

• Pullout platform steps in the bay floors enabling the drivers to step up and work at bay level

• External handles between the bays for workers to grab to give them better mechanical leverage during removal of the beverage product

• Multilevel shelving units that provided compartments for different products, gave easier direct access, and eliminated the problem of having to lift or move different products around to find the ones slated for delivery to a customer

• Lubricated two-wheel hand trucks with proper tire pressure maintained to make pushing and controlling the load easier

• Plastic beverage containers instead of glass ones to reduce package weight

• Improved beverage cartons designed with larger handles and smooth, contoured bases that make them easier to handle when removing stacked cartons from the truck

Changes in work risk factors were documented through videotaping, modeling the stresses imposed on the body by the materials handling tasks, continuous monitoring of heart rate, and analyzing discomfort surveys. Data were compared before, during, and after the ergonomic interventions were implemented.

The benefits of the ergonomic interventions were in proportion to the amount of time such controls were used. Reductions in stressors for the back and shoulders were observed when pullout steps, external handles, and multilevel shelving were used. Heart rates decreased for six of nine driver-sales workers during the study period, despite an increase in the product volume handled. The ergonomic interventions reduced the multiple handling of beverage cases and the awkward postures during beverage handling, resulting in a reduced number of reports of fatigue [McGlothlin 1995; NIOSH 1996].