NSC Text

1. NSC Text Chapter 4 - Anthropometry & Workplace Stressors SAFE4000; NSC Text Chap 4

2. Anthropometry • Measuring the human • Height, breadth, depth & distance • straight line measurements • Curvatures & circumferences SAFE4000; NSC Text Chap 4

3. Anthropometry • “Average worker” • No worker is average in every physical dimension • Workers in separate workplaces are likely different SAFE4000; NSC Text Chap 4

4. Anthropometry • Workplaces designed to accommodate 90% of population, leave out who? SAFE4000; NSC Text Chap 4

5. Anthropometry • Much of the available data (tables 4-1 & 4-2) is adapted from US military • Such data can help in designing workstations & job tasks SAFE4000; NSC Text Chap 4

6. Military Anthropometric Data • Biased toward younger workers • Close correlation to civilians except for hgt/wgt of females • limited data in figs 4-1 & 4-2 SAFE4000; NSC Text Chap 4

7. Anthropometry - Workstations • Should accommodate varying sizes & reaches • Adjustability is key SAFE4000; NSC Text Chap 4

8. Stressors • Stress results when outside forces exceed person’s tolerance • Results in bodily/mental tension SAFE4000; NSC Text Chap 4

9. Stressors • Sources of stress • Physiological • Biomechanical • Psychological SAFE4000; NSC Text Chap 4

10. Fatigue • No precise definition • Fatigue refers to • General feelings of tiredness • Reduction in work output • Physiological conditions resulting from continued work activity SAFE4000; NSC Text Chap 4

11. Manifestations of Fatigue • Muscular soreness • Aches • Sleepiness • Mental confusion • Muscular tension • General weariness SAFE4000; NSC Text Chap 4

12. Fatigue • Fatigue can result from physical or mental stressors • Mental Fatigue • Tiredness that occurs from mental rather than physical work SAFE4000; NSC Text Chap 4

13. Physiological Stressors • Kinetic stress results when body is subjected to rapid accelerations • One example is vehicular maneuvers SAFE4000; NSC Text Chap 4

14. Rapid Accelerations • Blood flow changes & may cause: • Loss peripheral vision • Illusions of motion • Total loss of vision • Loss of fine motor control • Unconsciousness SAFE4000; NSC Text Chap 4

15. Vibrations & acoustic noise may be considered together because they are both mechanical oscillations SAFE4000; NSC Text Chap 4

16. Both may interfere with other sensory functions & disrupt motor coordination & actual feedback SAFE4000; NSC Text Chap 4

17. Vibrations & Noise • Persistent noise induces anxiety & irritation • Severe V&N may interfere with internal organs & CNS • Discomfort • Disability • Death SAFE4000; NSC Text Chap 4

18. Other Types Of Physiological Stressors • Thermal - heat stroke • Atmospheric - decomp sick, anoxia • Chemical - inhalation/ingestion • Radiation - symptoms range from mild to death SAFE4000; NSC Text Chap 4

19. Other Types Of Physiological Stressors Physical work overload - extreme muscular exertion affects coordination & strength can lead to muscle spasm or collapse SAFE4000; NSC Text Chap 4

20. Other Types Of Physiological Stressors • Glare • annoyance, • discomfort • visual problem • Sleep deprivation - effects performance SAFE4000; NSC Text Chap 4

21. Sleep Deprivation • Can Adversely affect decision making process, may result in: • weariness • decreased strength • irritation • poor vision • hallucinations SAFE4000; NSC Text Chap 4

22. Psychological Stressors • Psychological Stressors may cause mental stress • Because tension may result in physiological problems... • may be unable to differentiate between physiological & psychological stressors SAFE4000; NSC Text Chap 4

23. Psychological Stressors • Ergonomists do not attempt to eliminate all sources of stress • Not all stress is disruptive • Limited amounts of stress serve to motivate workers SAFE4000; NSC Text Chap 4

24. Psychological Stressors • Too much concern or anxiety may cause operator to spend too much time focusing on selected displays & neglect other duties SAFE4000; NSC Text Chap 4

25. Monotony • Monotony results from inactivity, boredom, repetitive tasks • Mind dulling effects of monotony can seriously degrade performance SAFE4000; NSC Text Chap 4

26. Monotony • Uneventful vigilance tasks are examples tasks that produce stress via monotony • Closely aligned with monotony is sensory deprivation • Occurs when person is isolated from any perceptual input SAFE4000; NSC Text Chap 4

27. Excessive Task Speed/Load • …requirements can cause psychological & physical stress • This stress is associated with concern that task be completed successfully within time allotted SAFE4000; NSC Text Chap 4

28. Circadian Rhythm • 24 hr cycle of night & day • Basis for our regulation of eating sleeping, working, socializing • Disruptions can serve as both psychological & physiological stressors SAFE4000; NSC Text Chap 4

29. Circadian Rhythm • Disruptions (changes in work shift) can result in autonomic nervous system changes & neuro endocrine changes that are stressful SAFE4000; NSC Text Chap 4

30. Stress may also be the result of worker’s “life situation” external to the work environment SAFE4000; NSC Text Chap 4

31. NSC Text End Of Chapter 4 SAFE4000; NSC Text Chap 4