Lecture 13 Ergonomics Flashcards
Definition of Ergonomics:
-A discipline concerned with achieving an optimal relationship between
workers and their work environment.
Ramazzini and Ergonomics
- Studied the ill-effects of poor posture and poorly designed tools on the health of workers in early 1700s
-Began the aspect of ergonomics
Ramazzini’s two factors that have potential for harmful effects in worker health:
1)noxious vapors, fine particles and
materials handled
2) violent and
irregular motions and unnatural postures
of the body.
“Noxious vapors” refers to harmful or poisonous gases or fumes that can be inhaled and are potentially dangerous to health
Biomechanics
-study of the forces acting on the body.
* Gravity, skeletal muscle contraction
Anthropometry
study of the dimensions and physical characteristics
of the human body.
* Center of gravity, weights, volumes, lengths
(clothing size and chair size for example)
Work physiology
accounts for the metabolic costs of the workplace,
along with the prevention of work strain
Industrial psychology
a branch of psychology concerned with the
problems and management of the labor force
General Duty Clause
The Clause
In order to include the consideration of ergonomic
hazards in normal work place inspections without
the use of specific standards, OSHA has turned to
the provisions of Section 5 of the OSH Act or the
“General Duty Clause”
Section 5
Each employer must have a place of employment which are free from recognized hazards
that are causing or likely to cause death or serious physical
harm to his employees;
* shall comply with occupational safety and health standards
promulgated under this Act.
Criteria for enforcing ergonomic hazards
-An ergonomic hazard exists
* The hazard was recognized
* The hazard is either causing, or
is likely to cause, serious physical
harm to the employees
* There is a feasible means
available to reduce the hazard
In the United States today, what is the leading cause of work disability and pain?
musculoskeletal disorders
-(especially) Back injuries: chronic lumbar strain, herniated intervertebral disk, abnormal spine curvature (scoliosis, kyphosis, hyperlordosis)
- 80% of all Americans will suffer low back pain sometime during
their lifetime
Causes of back injuries
- Overexertion in lifting, pushing, pulling activities
- Sudden, sharp, rather than smooth lifting movements
- Extreme twisting
- Lifting of objects too far away from the body
- Use of back muscles, rather than leg muscles for lifting
- Poor postures, such as humped back and rounded shoulders,
slumped posture - Reaching above the shoulders, especially during lifting
- Vertical vibrations
Safe lifting
- Bring the load as close to the body as possible
- Lift the load with the back straight and knees bent
- The hold on the load should not be less than knee
height - Tie a rope sling or harness around a load without
handles - Avoid twisting the trunk while lifting
- Use mechanical aids to move objects, when
possible
More ergonomic-related health concerns:
Cumulative Trauma Disorder:
Cumulative Trauma Disorder: musculoskeletal impairments associated with repeated mechanical trauma in the workplace.
- Tendon disorders: tendinitis, tenosynovitis
- Muscle disorders: myalgia, trigger points
- Nerve disorders: Carpal tunnel syndrome, Guyon canal syndrome
- Vascular disorders: hand/arm vibration syndrome
- Bursa disorders: knee, elbow, shoulder
- Bones and cartilage: osteoarthritis
Physical work risk factors for developing CTDs (Cumulative Trauma disorders)
- Posture
- Repetition
- Force
- Compression
- Vibration
Posture
-Want to maintain Neutral body posture (position with least amount of pressure)
-Awkward postures outside of neutral can irritate tendons and compress nerves
-Static posture: holding posture for extended time (problematic because reduces blood flow to muscles
Repetition
- The same motion or group of motions over and over again
- Not typically a problem by itself, but magnifies other risk factors
- Different tasks can still use the same muscle groups, not allowing for
enough rest.
Force
- Amount of physical effort required for a task or motion.
- Tasks or motions requiring high force put a higher mechanical load on
muscles and tissues, leading to fatigue. - Force increasing when other risk factors (e.g. vibration) are present.
Compression
- Concentrated force on a small area.
- Can reduce blood flow or cause tissue injury
Vibration
- Single point vibration: applied to one body part, like the arm.
- Main outcome is decreased blood flow to that part of body
- Whole body vibration: vibration throughout entire body
- Main effect usually to spine, but can cause disorientation and motion
sickness.
Strategies to prevent Cumulative trauma disorders (CTDs)
- Redesign the job
- Minimize vibrations and cold temperatures (minimizes blood flow to hands)
- Change work-rest schedules
- Job rotation
- Tools should have proper grip size, handle length, and cushioned
handles - Gloves to reduce vibration and exposure to cold
- Knee pads for kneeling tasks
Guidelines for workstation design
1) provide easy access: removing obstructions, rearranging
2) Minimize pressure on the forearms: arm rests, padded edges
3) Minimize pressure on legs and feet: changes surface height, floor mats
4) Avoid standing in awkward postures: Eliminate twisting motions and lifting, avoid reaching down into boxes
Is there such thing as an ergonomic tool?
-It depends upon the use of the tool. A tool which is ergonomic in one
situation, may not be in another.
-General guidelines: Minimize forces and movements required, as well
as thermal and vibration exposure
* Use the right tool for the job
What are the different types of home ergonomics?
Cooking, Gaming, handwriting, cleaning (vacuuming, dusting…), Kitchen and bedroom ergonomics (bed length)
