Manual Material Handling PreventionControlTask Analysis SMU SAFETY FAIR

Manual Material Handling Prevention/Control/Task Analysis SMU SAFETY FAIR JULY 18, 2003

Session Objectives ® Discuss determining factors for “how much is too much” in manual handling jobs ® Discuss popular and practical approaches to controlling low back pain and disability ® Present engineering and administrative control strategies to eliminate or reduce low back pain and disability risk factors ® Overview of the 1991 revised NIOSH Lifting Equation and acceptable workload criteria ® Examples

Frequency/Cost

Low Back Pain Cause % Claims Manual Materials Handling 32 36 Slips and Falls-Same Level 13 11 Slips and Falls-From Elevation 10 % Cost 5

Low Back Pain Demographics - Gender ® Female 25. 9% ® Male 74. 1%

Anatomy of Back ® The back and torso provide the human form with a vertical support structure. The back/torso region contains several components, which include: l l l Vertebrae Discs Ligaments Muscles Spinal Cord Foramen

Anatomy of Back Each vertebra of the spine is separated from its neighboring vertebrae by the intervertebral discs. The discs provide cushioning between the vertebrae and allow for some degree of mobility, which enables the vertebrae to twist and bend in relation to one another. The overall structure of the discs and vertebrae is held together by ligaments, and moved through the action of muscles. The muscles also provide stability to the torso and allow for posturing of the back. The vertebrae themselves offer protection to the spinal cord, which passes between vertebrae via the foramen. Foramen is the space between vertebrae.

Acceptable Workloads ® Definition ® One that a worker can handle without triggering or aggravating Low Back Symptoms (Snook)

Occupational LBP Risk Factors *Snook, Campanelli & Hart 1978

Excessive Weights & Forces How Much Is Too Much? ® Determining Factors: ®Weights handled ®Task frequency & duration ®Distances Hand distances ® Pushing/pulling distances ® Carrying distances ® ®Undesirable body motions (bending, reaching, twisting) ®Initial & sustained forces (pushing/pulling)

Solution Categories ®Popular ®Practical

Popular Solutions ®Selection ®Training ®Back Belts ®Exercise

What is the right way to lift?

Correct Lifting

What is the right way to lift? ® Keep ® the load close to the body Worker brings object into contact with his body before lifting ® Avoid twisting Worker faces storage position squarely before lifting or placement ® Worker keeps shoulders and hips in alignment during lift ® During manual movement, the object stays over the worker’s feet ®

Back Belts ® No proof of effectiveness ® Because 50% of the population will feel uncomfortable wearing a belt, use should be voluntary, if at all ® Use of belts, braces and supports as prescribed by a physician for treatment of LBP may be beneficial

Exercise Programs ® Positive subjective findings ® Studies with reduced injury/claim reporting also have engineering and/or additional administrative controls ® U. S. Dept. Of Labor (Ergo. Program Mgt. Guidelines for Red Meatpacking Plants) says active exercises should be supervised by an occupational health nurse or physical therapist and that “exercises that involve stressful motions or that reduce rest periods may actually be harmful. ”

Exercise Programs ® Exercises should not be embarrassing or disruptive or cause work backlogs ® Exercises should be tailored to the problematic tasks ® Workers should be screened for preexisting medical conditions to avoid exercises which may be contraindicated

Practical Solutions Job Redesign Can Reduce Back Injuries by up to 1/3

Redesign of Strenuous Tasks Can Reduce Back Injuries by up to 2/3

Eliminating/Reducing Risk Factors ® Minimize weights and forces ® Minimize body motions ® Bending ® Reaching ® Twisting ® Minimize handling frequency of handling/re-

Controls ®Engineering ®Administrative

Minimize Weights and Forces ®Controls: ®Increase weight and handle mechanically ®Mechanize ®Decrease weight ®Convert to Push/Pull ®Reduce friction

Increase Weight & Handle Mechanically

Mechanizing Heavy Jobs

Minimize Bending ® ® ® Increased disk pressure Upper body weight Load Shifts center of gravity Moves load further away Leg muscles at a disadvantage 12% from bending alone

Minimize Bending "The work must be brought to the man waist-high. No worker must ever have to stoop to attach a wheel, a bolt, screw or anything else to the moving chassis. “ Henry Ford

Minimize Bending ® Controls: ®Lift mechanically ®Keep item off floor ®Provide lift table ®Store items between knuckle and shoulder height

Aids to Reduce Bending

Lifting and Lowering ® Associated with 49% of LBP ® Often involves bending ® Key sub factors: ® ® Heavy weights Frequent handling High or low lifts Long vertical travel

Minimize Reaching ® ® ® Shifts the load CG forward Increased difficulty in handling 3 x the force at full arm ext. Often forces a bend Additional risk factor for shoulder injury

Minimize Reaching ® Controls: ® Redesign workstation ® Store items between knuckle and shoulder height ® Keep objects close to body ® Reduce sizes

Minimize Twisting ® ® ® Increased disk pressure Increased torsional forces Asymmetrical loading Often performed under pressure or in a confined space 18% of all Low Back claims

Minimize Twisting ® Controls: ® Position all materials and tools in front of the worker ® Use conveyors, chutes, slides or turntables to change the direction of material flow ® Provide sufficient work area for whole body to turn ® Provide swivel chairs for seated workers ® Improve workstation layout ® Behavior modification

Pushing and Pulling “Assumed” to be easy ® Resistance, not weight is critical ® Key sub factors: ® ® ® High resistance levels Long distances Inclines Obstructions / surface cond.

Minimize Pushing and Pulling ® Controls: ®Use powered equipment ®Use as large a caster as practical ®Select casters based on floor surface ®Maintain casters and bearings

Minimize Pushing and Pulling

Carrying Slightly easier than lifting ® Usually associated with lift & lower ® Key Sub Factors: ® ® ® Heavy weights Frequent handling Long horizontal travels Walking with awkward load

Carrying ® Controls: ®Provide conveyor ®Provide cart ®Reduce distance

Minimize Frequency ® Controls: ®Automate duties ®Go to bulk handling ®Use carts/conveyors to reduce frequency of carrying ®Expand job scope

1991 NIOSH Lifting Equation ® Only lifting and lowering ® Quite a few limitations ® 8 hour shifts ® No carrying, etc. ® “Smooth” 2 -handed lifting ® Looks easy on paper, but more difficult in workplace ® Used by OSHA

1991 NIOSH Lifting Equation ® Lift/Lower ®Where object leaves surface ® Lift/Lower ®Where ® NIOSH Origin Destination object is set down equation only “looks” at these 2 discrete positions/postures

NIOSH – Angle of Asymmetry

NIOSH - Coupling ® Coupling refers to the quality and design of the handobject interface ® Coupling can be rated using the decision tree provided

NIOSH - Distance ® Distance is how far the load is lifted or lowered ® Subtract vertical location at origin from vertical location at destination for lifts ® Subtract vertical location at destination from vertical location at origin for lifts

NIOSH - Duration ® Short ® 1 hour or less followed by recovery time of 1. 2 times work time ® Medium ® 1 -2 hours followed by recovery time of 0. 3 times task time ® Long ® Durations between 2 -8 hours

NIOSH - Frequency ® Frequency is measured in lifts/lowers per minute ® Frequency is measured over a 15 minute period ® For multiple component tasks, frequency is for EACH task, not the overall frequency ® This frequency has different units than frequency for using psychophysical data

NIOSH - Horizontal/Vertical Location

NIOSH - Significant Control (Y/N) ® Enter a Yes if any of the following occur: ® The worker regrasps the load at the destination ® The worker momentarily holds the object at the destination ® The worker positions or guides the load at the destination

NIOSH - Object Weight ® Record maximum and average weight for lifts and lowers ® Use weight on object, scale in facility, or portable scale

Administrative Controls ® Administrative Controls: Early symptom reporting ® Rotation ® Job enlargement ® Exercise programs ® Breaks/interruptions ® Overtime control ® Controlled work hours ® Training including lifestyle training ® Participative ergonomics ®

Controlling Fatigue ® Fatigue Prevention Have a workscheduling policy ® Optimize stimulation during work ® Minimize the fatigue dose ® ® Fatigue Reduction Use “working” breaks ® Use frequent short breaks ® Maximize the recovery rate ® Increase recovery/work ratio ®

Summary ® Eliminate the need for manual handling ® Reduce task demands with mech. assists ® Available when needed, ® Suitable for the job and for the workers ® Control the risk factors ® Bending, Reaching, Twisting ® Lifting & Lowering ® Pushing & Pulling ® Carrying ® Analysis Tools ® Tools such as NIOSH Lifting Equation can help identify root causes and develop solutions