Ergonomics

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					Introduction to
  Ergonomics
    PUBH 3310
  November 4, 2011


                     1
    Supplemental Resources
• The Basics of Occupational Safety (course
  text)
  – Chapter 8 “Ergonomic Hazards: Musculoskeletal
    Disorders (MSDs) and Cumulative Trauma
    Disorders (CDTs)”
• Selected Internet websites, as noted in this
  presentation



                                                    2
                   Objectives
• This presentation is as an overview of
  occupational ergonomics
• Students should
  – Understand basics of ergonomics
       • Definitions
       • Diseases/injuries
       • Ergonomic risk factors
  –   Be aware of evaluation tools
  –   Know about controlling ergonomic hazards
  –   Be able to use anthropometry
  –   Know how OSHA deals with ergonomic issues
                                                  3
               Outline
• Definitions
• Recognizing ergonomic
  hazards/injuries/diseases
• Evaluating ergonomic hazards
• Controlling ergonomic hazards
• Regulatory issues (OSHA)

                                  4
                Definitions
• Ergonomics
  – Ergo = work, nomos = natural laws
  – Ergonomics is the science of adapting
    workstations, tools, equipment, and work methods
    for more efficient, comfortable, and error-free use
    by humans
  – Ergonomics incorporates all factors affecting work
    including, job demands, personal characteristics,
    and environmental conditions


                                                      5
                Definitions
• “Human Factors”
  – Essentially a synonym for ergonomics
  – Human factors design, human factors
    engineering, etc.
  – Degree programs available in this field




                                              6
               Introduction
• Ergonomics addresses the mismatch
  between task requirements and worker
  capabilities
• Ergonomic hazards are a serious risk
  – Most common cause of lost-time injuries and
    illnesses in most industries (28% of all injuries,
    according to 2009 BLS data)
• Human factors deficiencies also can cause
  errors, inefficiency and injuries/accidents
                                                         7
Ergonomic diseases/injuries
• Three major types of ergonomic injuries
  and incidents
  – Cumulative Trauma Disorders (CTD's)
  – Acute strains, sprains, and pulls
  – Incidents resulting from a poor human
    factors environment



                                            8
           Human Factors
• Human Factors Design
  – Controls, instruments, etc.
    should be intuitive
  – Displays should be clear
    and unambiguous
  – Learn about Bad Human
    Factors Design
     • http://www.baddesigns.com/   Which knob controls
                                    which burner?



                                                      9
Ergonomic diseases/injuries
•   Cumulative Trauma Disorder, CTD
    – Also known as Repetitive Strain Injury, RSI
    1. Musculoskeletal disorders, MSDs
       – Upper Extremity MSDs
       – Low-Back MSDs
    2. Nerve disorders
    3. Neuro-vascular disorders



                                                    10
Cumulative Trauma Disorders
•   Musculoskeletal disorders, MSDs
    –   Tendinitis
        •   Inflammation of the tendon
    –   Tenosynovitis
        •   Inflammation of the tendon sheath
    –   Ganglionic cysts
        •   Fluid-filled swelling, usually on the hand or foot
        •   “Bible Bumps”
    –   Epicondylitis
        •   Inflammation of the tendon attachment at the elbow
        •    “Golfer's elbow”, “Tennis elbow”
                                                                 11
Cumulative Trauma Disorders
• Nerve disorders
  – Carpal tunnel syndrome
     • Compression of the median nerve in
       the carpal tunnel of the wrist
     • Tingling and numbness of the thumb
       and first three fingers




                                            12
Cumulative Trauma Disorders
•    Neuro-vascular disorders
    – Thoracic outlet syndrome
      •   Compression of shoulder nerves and veins
          – Arm pain, numbness, or impaired circulation to the
            extremities
    – Raynaud's phenomenon
      •   “Vibration white finger”
    – Contact stresses (corners,
      edges, handles, etc.)
                                                             13
             Acute injuries
• Acute strains, sprains,
  and pulls
  – These “acute” incidents
    may actually be result
    of cumulative damage
  – Back injuries account
    for 20% of occupational
    injuries and illness, for
    a cost of 20 to 50
    billion dollars per year.
  – 5 of 6 people injure        14
    backs by age 85
             Acute injuries
• Many minor back
  injuries are muscle
  strains
  – These generally
    respond to rest and
    anti-inflammatory
    drugs
• Disk damage is a
  severe injury
  – May result in long-term
    disability, surgery, etc
                               15
         Ergonomic risk factors
•    Main risk factors
    1.   Force
    2.   Repetition/Duration
    3.   Posture
    4.   Contact trauma
•    Efforts to control ergonomic risk focus on
     these factors
    –    Other factors also are involved
         •   Environmental, personal

                                                  16
         Evaluation tools
• Ergonomists have a number of “tools” to
  evaluate work situations
   – NIOSH Revised Lifting Equation
   – Ohio Lifting Guidelines
   – Rapid Upper Limb Assessment (RULA)
   – And many more



                                            17
           Evaluation tools
• Online resources
  – OSHA e-tool for computer workstations
     • http://www.osha.gov/SLTC/etools/computerworkstations/i
       ndex.html
  – Analysis Tools for Ergonomists (Thomas E.
    Bernard, U of S Florida)
     • http://personal.health.usf.edu/tbernard/ergotools/index.ht
       ml
  – Washington State “WISHA” Ergonomics tools
     • http://www.lni.wa.gov/Safety/Topics/Ergonomics/Service
       sResources/Tools/default.asp

                                                                18
Controlling Ergonomic Hazards
• Recommendations
  – Perform job screening
     • Monitor ergonomic injuries
     • Identify high-risk jobs
  – Perform job analysis
     • Ergonomic evaluation tools
  – Prioritize and implement controls
     • Controls emphasize risk factors:
        – Force, Repetition/Duration, Posture, Contact


                                                    19
Controlling Ergonomic Hazards
• Control examples (hierarchy of controls)
  – Substitution
  – Engineering controls
     • Workstation layout, improved tools
  – Administrative controls
        –Job rules
           »Avoid “piece work” and incentives
            that increase risk
        –Worker rotation
        –Training, etc.
  – PPE                                       20
Controlling Ergonomic Hazards

• Examples
  – Improved hand tool design
     • Increased grip diameter
     • Tools that allow “neutral” joint posture
  – Padded or high-friction gloves
  – Adjustable benches


                                                  Pliers
 Adjustable                                         21
 work bench                      Scissors
Controlling Ergonomic Hazards
• Examples:
  – Office ergonomics
     •   Padded wrist rests
     •   Adjustable chairs
     •   Foot rests (for short people)
     •   “Ergonomic” keyboards




                                         22
Controlling Ergonomic Hazards
• Examples:
  – Lifting
     • Adjustable height pallets
     • Vacuum lifting devices




                                   23
            Anthropometry
• Anthropometry is the science of measuring
  the human body and incorporating this
  information into designs.
• The enormous variation between people can
  present challenges for designers.
• Designers must decide if they will:
  – Design for the extreme
  – Design for the average
  – Design for adjustability
• Recommended:
  – Design for 5% female to 95% male
                                              24
Anthropometry

  Body segment
  lengths expressed
  as proportion of
  body stature,
  useful for
  workplace design.




                      25
  Anthropometry
  example: What
  is the elbow
  height of the
  average 6-foot
  tall worker?



         Elbow = 0.630→
72 inches x 0.630 =
45.4 inches


                          26
    Ergonomics and OSHA
• Congress overruled OSHA’s new ergonomic
  standard in 2000
  – Now, ergonomic hazards are cited under the
    “General Duty Clause”
  – OSHA is expected to push for a new ergonomics rule
    under the Obama administration
• OSHA has provided much online information
  – Ergonomics web page
     • http://www.osha.gov/SLTC/ergonomics/index.html
  – Ergonomic e-tools
     • http://www.osha.gov/SLTC/ergonomics/outreach.html#etools
  – Etc.                                                  27
  Ergonomics and Workers
      Compensation
• Cases are carefully reviewed
• Generally require a period of exposure
  time to treat it as a chronic injury (e.g.
  can’t claim carpal tunnel after a week on
  the job)
• Your workers compensation company is
  a resource to help analyze problem and
  recommend solutions
                                          28
                Conclusions
• Ergonomics deals with humans and the work environment
• Human factors problems can lead to errors and accidents
• Cumulative Trauma Disorders (CTDs) include MSDs,
  nerve, and neuro-vascular disorders
• “Acute” injuries may be caused by cumulative damage
• Ergonomists use evaluation tools to asses hazards
• Ergonomic hazards are controlled by designing the task to
  match the human capabilities
• OSHA currently does not have an ergonomics standard
• Deal with these issues early to minimize them
         Acknowledgement
• Much of this presentation is based on material
  provided by Don Bloswick, PhD, Department of
  Mechanical Engineering, University of Utah,
  http://www.mech.utah.edu/people/faculty/bloswick.html.




                                                     30

				
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