9. Backrest height adjustment
- Many chairs have backrests that are fixed and do not raise or lower.
- When the backrest is not height adjustable, the lumbar support cannot be placed at the proper height on the employee’s back. Without lumbar support, the vertebrae and discs of the back do not stack properly on top of each other, increasing risk for stress and strain of tissues.
- The backrest must be fully adjustable in height within a range of at least 5”.
10. Backrest height adjustment with proper lock
- Some chairs have height adjustment that is supposed to lock the backrest in place, but the mechanism is faulty and the backrest slides down (e.g. chairs where you lift the backrest up and it is supposed to stay up on its own)
- When the backrest does not lock properly, the lumbar support cannot be placed at the proper height on the employee’s back resulting in problems as described above.
- The backrest must have a locking lever (a knob can be substituted, but it requires extra force to tighten and can loosen with wear).