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Course 711 - Introduction to Ergonomics

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

Risk Factors in the Environment

Factors inherent in the environment.
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Heat Stress

Externally generated heat in the workplace can cause an excessive total heat load on the body, which can result in heat stroke, a potentially life-threatening condition.

Heat exhaustion, heat cramps, dehydration, electrolyte imbalance, and loss of physical/mental work capacity can also result from heat stress.

Heat stress is made even more dangerous in the presence of high humidity due to the reduced ability of the body to cool itself.

High-temperature conditions at work may be brought on by:

  • Summer heat;
  • Tropical heat;
  • Heat from engines;
  • Heat from chemical processes and reactions;
  • Body heat;
  • Welding; and/or
  • Friction.

1. Heat stress is made even more dangerous in the presence of _____.

a. high illumination
b. low humidity
c. moderate wind
d. high humidity

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Cold Stress


If the worker is exposed to an environment so cold that the body cannot maintain adequate deep core temperature, hypothermia, which can also be life-threatening, may result. Symptoms brought on by cold stress include:

  • Shivering;
  • Clouded consciousness;
  • Pain in the extremities;
  • Dilated pupils;
  • Reduced grip strength and coordination; and/or
  • Possibly ventricular fibrillation.

Low temperature conditions may be caused by:

  • Winter cold;
  • High altitudes;
  • Refrigerated surfaces; or
  • Cryogenic lines and equipment.

These can result in muscle strain as well as cold "burns," frostbite, and hypothermia.

For more detailed information about staying safe in extreme temperatures, please click here to go to our 602: Heat and Cold Stress Safety.

2. Connie is exhibiting shivering, dilated pupils, clouded consciousness and reduced coordination. Which of the following conditions is indicated by these symptoms?

a. Hyperthermia
b. Dermatitis
c. Heat stress
d. Hypothermia

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Lighting in one workstation may be appropriate, but for another workstation, that same lighting may be potentially harmful. Illumination may be too high, too low, or cause glare. Lighting required for general lighting in general construction areas, warehouses and workplace hallways and corridors is five foot-candles (54 lux). Physical plants, shops, machining areas, equipment and work rooms is 10 foot candles (108 lux), and office areas require at least 30 foot-candles (323 lux) of illumination.

Outside lighting is an important factor to consider. Light for outside work should aid production and, at the same time, be high enough to be safe.

Adequate general and local lighting must be provided for rooms, building, and work areas during the time of use. Below is a list of factors that influence the adequacy of illumination.

Position monitors 90º from windows.
  • The quantity of light as specified in American National Standard ANSI All.1-1965, "American Standard Practice for Industrial Lighting".
  • The quality of light in terms of freedom from glare, diffusion, and distribution. For instance, computer monitors should be placed at a 90º position from windows to prevent glare. Overhead light should be diffuse and indirect.
  • Freedom from shadows and extreme contrasts.

It's interesting to note that lighting has been used to treat depression associated with light deprivation, and may also affect biological clocks and sleep patterns in humans. Although controversial, light has been used to maintain alertness and to increase productivity in shift workers.

3. To prevent excessive glare and eyestrain from an outside window, place the computer monitor _____.

a. facing the window
b. directly in front of the window
c. at a right angle to the window
d. facing 180 degrees from the window

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Noise is any sound that is unwanted. It can be so powerful as to cause pain in the ears, or it may represent only a nuisance. Its pitch may be quite high or very low; its duration, continuous or intermittent; and its onset, sudden or gradual.

Excessive exposure to noise may lead to hearing disorders including:

  • Deafness. A deaf person has little to no hearing. Temporary or permanent hearing loss may occur in one or both ears.
  • Tinnitus. Tinnitus is the hearing of sound when no external sound is present
  • Paracusis. Paracusis is a form of impaired hearing that results in auditory illusions or hallucinations.

The louder the noise and the longer the duration, the greater the risk of injury. Nuisance noise may interfere with a worker's ability to focus or concentrate on the work at hand, and may therefore, actually be the indirect cause of an accident.

Oregon OSHA conducted measurements and found sound levels produced by computer workstations and associated equipment to be consistently below those that damage hearing. However, equipment noise can still be disruptive, annoying, or distracting, and many people are sensitive to the low-level, high-frequency noise that the Central Processing Unit (CPU) may emit. As a result, ambient sound levels should be kept below 55 decibels on the A-scale (dBA). Also, narrow-band tones above ambient sound levels should be reduced. It is good practice to isolate main CPUs and disk drives and provide noise-control covers on high-speed printers.

4. Which of the following disorders involves the hearing of sound when no external sound is present?

a. Deafness
b. Tinnitus
c. Vibration Syndrome
d. Paracusis

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Psychosocial Risk Factors


A healthy ergonomic work environment depends a great deal on the attitudes of those involved. How management handles or responds to problems or concerns relating to ergonomics may determine the development and the severity of many problems in the workplace. To create a healthy, more stress-free work environment, consider these important points:

  • All employees should understand their work roles;
  • End users should participate in the selection of equipment they will use; and
  • Employers should provide adequate operator ergonomics training.

Psychosocial Factors and MSDs

Various studies suggest that perceptions of increased workload, monotonous work, limited job control, low job clarity, and low social support are associated with various work-related musculoskeletal disorders (MSDs). The effects of these factors on MSDs may be, in part or entirely, independent of physical factors.

5. To create a healthy work environment that reduces the risk of ergonomic injuries, management should _____.

a. let end users select equipment and tools
b. discourage employee participation
c. look at employee suggestions annually
d. purchase chairs based on price

Check your Work

Read the material in each section to find the correct answer to each quiz question. After answering all the questions, click on the "Check Quiz Answers" button to grade your quiz and see your score. You will receive a message if you forgot to answer one of the questions. After clicking the button, the questions you missed will be listed below. You can correct any missed questions and check your answers again.


Crazy SAIF

If you like "rap" music, watch this short crazy video by SAIF Corporation on office ergonomics.

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