Introduction to Ergonomics Lecture Notes PDF

lecture 1 Introduction to ergonomics By Dr. Fatma Shehata Important notes Ergonomics code : (PT-326) Total marks /100 Credit hours /2hours Assessment : 60 marks / final exam 20 marks / mid term 20 marks / semester work :-a-10 mar...

lecture 1 Introduction to ergonomics By Dr. Fatma Shehata Important notes Ergonomics code : (PT-326) Total marks /100 Credit hours /2hours Assessment : 60 marks / final exam 20 marks / mid term 20 marks / semester work :-a-10 marks /task analysis b-10 marks / quiz Items: 1- Definition of ergonomics 2- Human machine system 3- Benefits of ergonomics 4- Strategies of ideal human machine system 5- Work-Related Musculoskeletal Disorders 6-Risk Factors Associated with MSDs 7- Prevention of Musculoskeletal Disorders Definintion:- Ergo+ nomics =ergonomics work + rules or laws = “the laws of work Ergonomics defined as : is the scientific study of the people and their work. Ergonomics is the science of fitting workplace conditions and job demands to the capabilities of employees. Applying the ergonomics principles is necessary to improve the FIT between the worker and the workplace. This chart shows how MSDs compare to other hazards based on percentage of injuries and illnesses using statistics from the Bureau of Labor Statistics, FY2014. A practical approach to ergonomics should provide a good match between the human , machine and the work environment. Human – machine interaction:- Human machine interaction occurs through three simple processes includes : Data input output processing Benefits of ergonomics:-  It makes the job more pleasant and decrease turnover. Improper HM fitting leads to….. Work-Related Musculoskeletal Disorders (MSDs) Common MSD disorders includes:- Carpal Tunnel Syndrome Rotator Cuff Tennis Elbow Neuritis Bursitis Reynaud’s Syndrome Ischemia Trigger Finger De Quervain’s Thoracic Outle Syndrome Sciatica Epicondylitis Herniated Discs Back strain/disability Neck strain/disability Tendinitis Musculoskeletal Disorders (MSDs) Affect the muscles, nerves, blood vessels, ligaments, and tendons Symptoms may includes : −Discomfort −Swelling −Pain −Tingling −Numbness −Inflammation −Loss of motion/flexibility −Throbbing −Spasticity −Paralysis −Stiff joints −Burning  Common Work-Related MSDs areas Most commonly affected areas: Back Arms, Elbows, and Shoulders Neck Hands, Wrists, and Fingers Knees, Ankles, and Feet  Risk Factors Associated with MSDs Risk factors of MSD injuries dependent upon: Work positions and postures How often task is performed Level of required effort and duration of task N. B: Pain results from increasing stress on the body structure when there any deviation from neutral position Any deviation from neutral position causes imbalance between external force and internal force because muscles have to exert more force. If the work related stresses increase , the load on the body structure increase and pain will start as a protective mechanism and a sign of overuse. The neutral position is the safest and the most efficient position during work because the joints are most efficient when they operate closest to the mid- range of the joint. Examples of Awkward body postures  Risk factors include: 1-Exerting excessive force Lifting heavy objects/people Pushing or pulling heavy loads Manual pouring materials Maintaining control of equipment or tools 2-Performing same/similar tasks repetitively: job considered highly repetitive if the cycle time is 30 seconds  3-Working in awkward postures or same postures for long periods Squatting Leaning over a counter/bending Using a knife with wrists bent Kneeling Awkward posture place excessive force on joint and overload muscles and tendons around the effected joint. 4- (poor design of the equipment)Localized pressure into the body part Source: OSHA Pressing the body/part of the body against hard or sharp edges Using the hand as a hammer Contact stress on apart of the body interfere with the circulation and nerve function and cause local tissues irritation.. 5-Vibration Whole body Hand-arm 6- environmental factors : (temperatures – lightening , noise , ventilation ) 7-psycho-social issues:- anxiety or job dissatisfaction Preventing Musculoskeletal Disorders: 1.Improved Work Techniques: the best way to complete a job by keeping the goal of decreasing your risk factors in mind. For example, be sure to utilize helpful equipment such as dollies, carts, forklifts and platforms in order to keep you from injuring yourself. 2.Personal Protective Equipment (PPE): PPE is designed specifically to reduce the risk of injury. Wearing shoulder and knee pads and vibration- reducing gloves can really make a difference when working for hours at a job site. 3-Better tools and resources: It’s important to ensure that the hand tool you’re using fits the job you are doing and reduces the applied force. Using the wrong tool can cause discomfort and long-term side effects. 4-Training: Learning about Musculoskeletal Disorders should not happen on the job, but rather before the job. Workers must learn about the risk factors of MSD’s and how to make ergonomic changes in order to prevent them 5-Proper Stretching: Suggest a work site stretch and flex program. This presents a great opportunity for team bonding and communication while preparing each employee’s body for the work ahead of them. 6- improve Environmental factors: Taking care of the work climate, noise and temperature ,( extreme heat increased fatigue , extreme cold constricts blood vessels and reduced sensitivity) so employee should work in a good temperature. 7- Rest breaks and recovery pauses : Breaks at launch time and afternoon are important part of allowing employees time to recover from the demands both mentally and physically. Recovery pauses : breaks (2-3minute/one hour) in addition to usual breaks may help to reduce discomfort while improving productivity. Prevention of Musculoskeletal Disorders in the Workplace: Ergonomic Control Examples  Awkward body postures - hazards Working with the neck or back bent forward more than 30° for more than 2 hours per day Source of graphics: OSHA  Squatting for more than 2 hours per day Source of graphics: OSHA  Kneeling for more than 2 hours per day Source: OSHA  Awkward body postures - solutions Raise and/or tilt the work for better access Use a stool for ground-level work Source: OSHA Source: NIOSH Source: OSHA  Awkward body postures - solutions Use tools with longer handles Alternate between bending, kneeling, sitting, and squatting Source: OSHA Source: NIOSH Source: OSHA  Awkward grips - hazards Gripping 10 or more pounds or force for 2 or more hours per day Source of graphics: OSHA  Awkward grips - hazards Pinching 2 or more pounds of weight or 4 or more pounds of force for 2 or more hours per day Source of graphics: OSHA  Awkward grips - solutions Design work layout to reduce hand-carrying Reduce amount of items carried at one time Use non-pinch grip postures Use ergonomically designed tools/aids Use job/task rotation “C” shaped posture Source of graphics: OSHA  Repetitive motions - hazards Repeating same motion for more than two hours per day with hands, wrists, elbows, shoulders, or neck  Repetitive motions - hazards Intense keying for more than 4 hours per day Source: OSHA  Repetitive motions - solutions Arrange work to avoid unnecessary motions Let power tools and machinery do the work Spread repetitive work out during the day Take stretch pauses Rotate task with co-workers if possible Change hands or motions frequently Source of graphics: OSHA  Localized pressure on body part - hazards Pressing the body/part of the body against hard or sharp edges Standing/kneeling for prolonged periods on hard surfaces Using tools with hard handle surfaces or short handles Source of graphics: OSHA  Localized pressure on body part - hazards Using hands/knees as a hammer more than 10 times in 1 hour or more than 2 times per day (long-term) Source of graphics: OSHA  Localized pressure on body part - solutions Use tools with longer handles Use tools with padded grips Alternate between bending, kneeling, sitting, and squatting; use sit/stand stools or tables Source of graphics: OSHA  Localized pressure on body part - solutions Pad table edges or use tables/desktops with rounded edges Use wrist rests, anti-fatigue mats, knee pads, shoe inserts or other items that reduce stress on body parts Source of graphics: OSHA  Lifting objects - hazards Lifting more than 75 lbs. once/day 55 lbs. ten times/day 10 lbs. more than twice/minute or for more than 2 hours/day 25 lbs. above shoulders, below knees, or at arms length more than 25 times/day Source of graphics: OSHA  Lifting objects - hazards Heavy, frequent, and awkward lifting  Lifting - solutions Managing for safer lifting Plan lifts Minimize lifting distances Position materials to power zone levels Avoid manually lifting/lowering loads to/from floor Identify/reduce unstable or heavy loads Reduce frequency of lifting and duration of lifting tasks Provide clear access Source of graphics: NIOSH  Lifting - solutions Employee guidelines for safer lifting Stretch before lifting Check for tags on loads Test load for stability and weight Plan the lift Use proper lifting techniques – grip; two hands; smooth, even motions; load close to body; legs to push up and lift load; avoid twisting; alternate with less physically demanding tasks; rest breaks Get assistance when necessary  Lifting - solutions Use proper lifting techniques Caution: This technique may be effective only if loads are small, light- weight, and can easily fit between the knees. Keep the load close to your body and lift by pushing up with your legs. Source: NIOSH Vibration – hazards Moderate – more than 2 hours per day High – more than 30 minutes per day Prolonged Source of graphics: OSHA Vibration – solutions Use low-vibration tools and devices that may reduce vibration (tool balancers, extension handles, vibration isolators, damping techniques) Adequate rest periods Rotate jobs Maintenance PPE Source of graphics: OSHA  Case study: A computer programmer referred to the physiotherapist with complaints of numbness and loss of strength in both of his hands. He is required to use his keyboard at work for along time. Apply ergonomic principles to relieve pain Answer: using adjustable keyboard tray with wrist rest Ask him to take short breaks in addition to usual breaks and make stretching exercises for his hand muscles.