April 14, 1998

Engineers' Work to Reduce Back Injury in Home Building Industry

Two of Dr. Gary Mirka's graduate students, Jennie Psihogios and Daniel Kelaher, illustrate the use of a Lumbar Motion Monitor at a construction site to quantify low back stress during construction work activity.

Springtime brings the sweet perfume of flowers and the soft colors of budding trees, but in the burgeoning Triangle, there's something else in the air -- the sound of hammering nails and sawing boards from new home construction. The recent surge in home building is a result of the booming economy, but with increased construction comes a surge in construction-related low back injury. At NC State University, Dr. Gary Mirka, assistant professor of industrial engineering, and Dr. Leonard Bernold, associate professor of civil engineering, are working with epidemiologists to reduce the risk of low back injury in the home construction industry.

To conduct this research, Mirka has enlisted the help of the North Carolina Home Builders Association, the Raleigh-Wake County Home Builders Association and Raleigh and Wake County contractors. Epidemiologists from Duke University surveyed workers from three trades--masonry, framing and drywall hanging--identified as high risk based on injury records. From the survey results, the researchers create a baseline of workers' health and comfort.

In addition to assessing risk using the survey's anecdotal information, Mirka is developing tools that will provide biomechanical data to indicate risk factors. To produce a biomechanical measurement model, Mirka initially selected three local builders to conduct on-site studies. He uses tools, such as a lumbar motion monitor, a device that measures and records back movements, and other methods to design a model that can be applied to construction work and can pinpoint the activities that can lead to injury. From the information collected, Mirka can calculate the risk of lower back injury for any particular activity.

"Once we have isolated the activities that can cause injury, we will look at ways to reduce those risks by modifying equipment or changing processes," says Mirka. "For example, we are aware that repetitive motion can cause damage to the lower back, so we are developing ways to reduce repetitive movements on the work site. The activities that we are looking at as specific high-risk activities include those that involve awkward postures, such as using nail guns for flooring installation, handling heavy loads, such as moving lumber or dry wall, and repetitive bending and twisting activities, such as those required while laying brick," says Mirka. "These activities seem to be the most likely to produce the greatest risk of injury."

Funded by the National Institute for Occupational Safety and Health (NIOSH), the three-year project is in its second year. The thrust of the project in the second year is to design tools and aids that can reduce the stress on the lower back. This work is being done under the direction of Bernold. His goal is to modify equipment and activity to reduce risk while maintaining cost efficiency. His proposals include rearranging raw materials and redesigning tools to reduce stress on the spine. Mirka and Bernold have focused on small home builders because they are the most vulnerable to injury problems due to their often limited resources. The results of the study will help them illustrate the importance of low cost, effective improvements that can reduce low back injury risk factors. They also see this project as an opportunity to educate the work force.

"The challenge is to develop tools that reduce load without reducing productivity," says Mirka. "We don't want to create a situation in which the modification is cost prohibitive for the employer or the construction worker. If the cure is too costly, it will not be used and the risk will continue to exist."

The knowledge gained from this research will be usable in commercial construction and a variety of other industries. Mirka suggests that the warehousing industry, in particular, could benefit from his findings.

"It is our hope that we can bring some of our knowledge of ergonomics to this low-tech industry and improve the longevity of the construction worker," says Mirka. "Currently, a construction worker may suffer from low back pain after only a few years on the job. We would like to prevent that from happening so that workers do not end up injured and unable to work."

Technical Contact: Dr. Gary Mirka, (919) 515-6399, mirka@eos.ncsu.edu

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