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Course 750 - Introduction to Industrial Hygiene

Safety guides and audits to make your job as a safety professional easier

Ergonomic Hazards


Ergonomic Risk Factors

The science of ergonomics studies and evaluates a full range of tasks including, but not limited to, lifting, holding, pushing, walking, and reaching.

Many ergonomic problems result from technological changes such as increased assembly line speeds, adding specialized tasks, and increased repetition; some problems arise from poorly designed job tasks. Any of those conditions can cause ergonomic hazards such as excessive vibration and noise, eye strain, repetitive motion, and heavy lifting problems.

Improperly designed tools or work areas also can be ergonomic hazards. Repetitive motions or repeated shocks over prolonged periods of time as in jobs involving sorting, assembling, and data entry can often cause irritation and inflammation of the tendon sheath of the hands and arms, a condition known as carpal tunnel syndrome.

Ergonomic hazards are avoided primarily by the effective design of a job or jobsite and better designed tools or equipment that meet workers' needs in terms of physical environment and job tasks. Through worksite analysis, employers can set up procedures to correct or control ergonomic hazards by:

  • using the appropriate engineering controls (e.g., designing or re-designing work stations, lighting, tools, and equipment);
  • teaching correct work practices (e.g., proper lifting methods);
  • employing proper administrative controls (e.g., shifting workers among several different tasks, reducing production demand, and increasing rest breaks); and,
  • if necessary, providing and mandating personal protective equipment.

Evaluating working conditions from an ergonomics standpoint involves looking at the total physiological and psychological demands of the job on the worker.

Overall, industrial hygienists point out that the benefits of a well-designed, ergonomic work environment can include increased efficiency, fewer accidents, lower operating costs. and more effective use of personnel.

1. The science of ergonomics involves the study and evaluation of a full range of tasks including, but not limited to, _____.

a. memory processing and recall
b. visual acuity and spatial recognition
c. lifting, holding, and pushing
d. verbal production and processing

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Ergonomic Guidelines

A major component of ergonomics is the development of industry-specific and task-specific guidelines to reduce and prevent workplace musculoskeletal disorders (MSDs). These voluntary guidelines are tools to assist employers in recognizing and controlling ergonomics-related risk factors. Employers in other industries for which guidelines have not been developed may find useful information in these guidelines for implementing their own ergonomic programs.

Current Ergonomics Guidelines

OSHA issued the ergonomic guidelines for the shipyards industry on February 28, 2008. OSHA issued the ergonomic guidelines for the poultry processing industry on September 2, 2004. OSHA issued the ergonomic guidelines for the retail grocery stores industry on May 28, 2004. OSHA issued the ergonomic guidelines for the nursing home industry on March 13, 2003. The document was updated on September 12, 2005.

Previously Completed Ergonomic Guidelines

2. OSHA publishes voluntary _____ to help employers in specific industries develop ergonomics programs.

a. guidelines
b. standards
c. rules
d. regulations

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Basic Ergonomic Principles

NOTE: For a more thorough introduction to ergonomics refer to OSHAcademy Course 711 - Introduction to Ergonomics

Ergonomics (er'gõ nom'iks):

  • The study of work and the relationship of work to the physical and cognitive capabilities of people.
  • Fitting the job (tools, tasks, and environment) to the employee, instead of forcing the worker to fit the job.

Ergonomic principles are derived from many areas, including:

  • Biomechanics
  • Physiology
  • Anthropometry
  • Industrial engineering
  • Safety

3. Ergonomics principles are based on _____.

a. fitting the worker to the job
b. fitting the job to the worker
c. designing the job with fewer steps
d. engineering automation into work

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Ergonomic Injuries

Classifications of Ergonomic Injuries

There are two classifications of ergonomic injuries, and they are:

  • Cumulative Trauma Disorders (CTDs) - exposure driven
  • Strains/Sprains - instantaneous (event driven)

Characteristics of Cumulative Trauma Disorders (CTDs) are:

  • Injury to soft tissue caused by prolonged exposure to multiple ergonomic risk factors
  • Typically develop in small body segments (i.e. fingers, wrists, elbows, and neck)

Examples of CTDs

Tendon disorders:

  • Inflammation of tendon and/or tendon sheathing caused by repeated rubbing against ligaments, bone, etc.
  • Lateral epicondylitis (tennis elbow)

Nerve disorders:

  • Compression of nerves from repeated or sustained exposure to sharp edges, bones, ligaments, and/or tendons
  • Carpal tunnel syndrome

Neurovascular disorders:

  • Compression of blood vessels and/or nerves from repeated exposure to vibration or cold temperatures
  • Raynaud's phenomenon (white finger syndrome)

Characteristics of Strains & Sprains

  • Injury to connective tissue caused by single forceful event: lifting heavy objects in awkward position
  • Common to large body segments (i.e. back, legs, and shoulders)
  • Risk of injury increases with the presence of multiple risk factors

4. Which of the following is an example of a strain or sprain?

a. White finger syndrome from using a hydraulic jack
b. Carpal tunnel syndrome from typing
c. Tennis elbow from chopping produce
d. Back injury when lifting an object

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Early Reporting of Ergonomic Issues

It is critical for employees to understand the importance of reporting ergonomic issues sooner rather than later to help prevent serious injuries from occurring.

Proactive Reporting

  • Report suspected ergonomics risk factors to your supervisor and safety committee representative

Early Reporting Process

  • Report pain or discomfort associated with work to your supervisor and Occupational Health Services

Benefits to Early Reporting

  • Leads to early care and quicker healing, preventing chronic problems
  • Leads to quicker identification of the root cause of the injury
  • Will initiate an ergonomics evaluation by trained personnel

5. What leads to early care and quicker healing, preventing chronic ergonomic problems?

a. regular supplementation
b. root-cause assessment
c. early reporting
d. careful analysis

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Stretching Basics

Stretching helps reduce the likelihood of ergonomic injury from occurring in the workplace. An effective stretching program in the morning can help to reduce the likelihood and severity of ergonomic injuries during the rest of the workday. Some employers give incentives to their employees for voluntarily participating in stretching programs because they know stretching benefits both the worker and the company.

The Benefits of Stretching

  • Increases flexibility/elasticity of muscles
  • Increases circulation to warm the muscles, improving mental alertness, reducing fatigue
  • Decreases muscle tension and stress

When to Stretch

  • Prior to starting your day
  • During short breaks (at least once per hour)
  • After breaks or lunch to prevent fatigue
  • If tension or stress is apparent
  • After a lengthy task duration or an extended awkward posture

Proper Stretching Techniques

  • Relax and breathe normally. Do not hold your breath.
  • Hold each stretch for a count of 15, or as long as comfort is maintained.
  • Use gentle, controlled motions. Do not bounce!
  • Keep the knees slightly bent for better balance.
  • Stretch until a mild tension is felt, then relax.
  • Stretch by how you feel and not by how far you can go.

6. An effective stretching program in the morning can _____.

a. reduce the number of OSHA inspection during the year
b. help to reduce the likelihood and severity of ergonomic injuries
c. keep the employer in compliance with OSHA ergonomics rules
d. control employee work practices during the workday

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Ergonomic Risk Factors
(Figure 1)
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Ergonomic Risk Factors

The risk of MSD injury depends on work positions and postures, how often the task is performed, the level of required effort and how long the task lasts. Risk factors that may lead to the development of MSDs include:

  • Exerting excessive force. Examples include lifting heavy objects or people, pushing or pulling heavy loads, manually pouring materials, or maintaining control of equipment or tools.
  • Performing the same or similar tasks repetitively. Performing the same motion or series of motions continually or frequently for an extended period of time.
  • Working in awkward postures or being in the same posture for long periods of time. Using positions that place stress on the body, such as prolonged or repetitive reaching above shoulder height, kneeling, squatting, leaning over a counter, using a knife with wrists bent, or twisting the torso while lifting.
  • Localized pressure into the body part. Pressing the body or part of the body (such as the hand) against hard or sharp edges, or using the hand as a hammer.
  • Cold temperatures. In combination with any one of the above risk factors may also increase the potential for MSDs to develop. For example, many of the operations in meatpacking and poultry processing occur with a chilled product or in a cold environment.
  • Vibration. Both whole body and hand-arm, can cause a number of health effects. Hand-arm vibration can damage small capillaries that supply nutrients and can make hand tools more difficult to control. Hand-arm vibration may cause a worker to lose feeling in the hands and arms resulting in increased force exertion to control hand-powered tools (e.g. hammer drills, portable grinders, chainsaws) in much the same way gloves limit feeling in the hands.
  • Combined exposure to several risk factors. May place workers at a higher risk for MSDs than does exposure to any one risk factor.

7. Which of the following ergonomic risk factors may cause a worker to lose feeling in the hands and arms, resulting in increased force exertion to control hand-powered tools?

a. Awkward positions
b. Vibration
c. Cold temperatures
d. Excessive force

Check your Work

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