environmental

Using the Hierarchy of Controls to Address Manual Lifting

Man lifting a box

When it comes to ergonomics and musculoskeletal disorder (MSD) risk factors, force plays the biggest role. This issue has been clearly reflected in workplace injury data throughout the United States. In 2021, Liberty Mutual reported that "disabling workplace injuries cost businesses more than $58 billion every year," with the number one contributing category being overexertion involving outside sources, i.e., handling objects.

Overexertion can result from different activities like pushing, pulling, lifting, or carrying objects. Identifying and quantifying the risk associated with these types of activities is step one in the job improvement process and can easily be analyzed using assessment tools like the NIOSH lifting equation and the Snook and Ciriello Push/Pull/Carry tables. These results should be evaluated, and a root cause analysis completed to truly understand where the underlying risk stems from. The second and often most difficult step in the job improvement process is identifying and implementing improvements to address and reduce the risk associated with the task.

When brainstorming and prioritizing ergonomics improvements, the hierarchy of controls should be utilized to reduce risk as much as feasibly possible, while still maintaining the highest return on investment.

For manual lifting, consider the following solutions.

In a perfect world, you could entirely eliminate MSD risk.

To eliminate risk, operator involvement in the task should be minimized and high forces engineered out. This can be accomplished with solutions such as:

  • Equipment like automatic palletizers
  • Bulk ordering of supplies like super sacs to eliminate handling of smaller bags
  • Lift assists – vacuum, pneumatic, hoists

But, if you can't eliminate risk, you can change equipment to reduce risk.

When eliminating the risk just isn't possible, equipment and workstation set up should be modified to reduce force and allow for manual lifting within the most optimal positions. This can be done through changes such as:

  • Raise conveyors and pallets so that items are handled within the optimal hand working height zone
  • Tool balancers to offset the weight of heavy tools
  • Lift and tilt tables or fixed angled stands for pallets and bins to minimize horizontal reach during item retrieval

Use administrative controls to help reduce risk in the meantime. 

Administrative controls should only be used temporarily while engineering solutions are being developed and implemented. Some examples of administrative controls include:

  • Job rotation – ideally the jobs being rotated through should allow operators to utilize varying muscle groups
  • Provide more frequent breaks

Establish work practices to reduce MSD risk to supplement your other improvements.

Work instruction and coaching have a relatively low return on investment and risk reduction compared to the previously listed controls and rely on individuals to make a conscious effort to change their behavior, making them an unreliable solution. Methods of instruction and coaching may include:

  • Advising operators to perform team lifts on objects over a certain weight
  • Coaching operators on proper lifting technique

To recap, solutions that will eliminate MSD risk from the job activity will have the greatest level of risk reduction as well as return on investment. Controls further down the list of the hierarchy of controls will not provide a reliable, significant, or consistent level of risk reduction and should only be used temporarily until engineering solutions can be implemented. For more information on addressing manual material handling risk in job activities check out the following resources:

 

2021 Workplace Safety Index: the top 10 causes of disabling injuries (business.libertymutual.com)