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NIOSH Equation

The NIOSH equation determines the recomanded weight limit for lifting tasks, load ports, manual handling without movement. In the case where the load handled is less than the recomanded weight limit, the operators do not run any risk of occurrence of low back pain.

The Recommended Weight Limit defines the maximum weight that can be lifted by nearly all healthy employees during an 8-hour shift without increasing the risk of a musculoskeletal disorder in the lower back.

Drawing NIOSH Equation


NIOSH equation PDF
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Niosh PDF

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Automate your ergonomic analyses with Nawo Live, with access to multiple methods and ergonomic standards.


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The NIOSH equation can be used to assess two-handed lifting and lowering tasks, including their impact on the back.

It is especially useful in the case of workers who lift loads whose weight is always the same.It can be useful in any work environment where workers perform tasks of lifting or lowering inert loads (i.e. excluding handling living things) with both hands.

The equation takes into account biomechanical, environmental factors and duration.

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Restrictions and limitations

The NIOSH equation does not take into account whole-body vibration or the risks of MSDs that are not associated with raising or lowering.

The method cannot be used in the following cases:

  • Lifting or lowering with one hand, on slippery floors or in unfavorable conditions (tight spaces …), in a seated or kneeling position, of unstable objects, people or animals;
  • Tasks performed for more than eight hours;
  • Transport, push or pull tasks (including using a wheelbarrow or shovel).

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Apply the NIOSH Equation with Nawo Live

Nawo Live is your physical activity risk assessment tool for identifying risk factors for musculoskeletal disorders (MSDs).

In Nawo Live, automate and evaluate all biomechanical risk factors using reference methods (RULA, REBA, NIOSH, etc.).

Nawo Live guarantees you a reliability of the measurements acquired by our systems, including :

  • Automation of MSD risk factor calculations
  • Reliability of acquired data
  • Time saved by analysing thousands of postures
  • Exportable statistics in Excel format providing decision support