Physical Agents

1. © 2008 by Nelson, a division of Thomson Canada Limited. 1 Chapter 4 Physical Agents

2. © 2008 by Nelson, a division of Thomson Canada Limited. 2 Learning Outcomes After reading this chapter, you should be able to: Define the numerous terms relating to physical agents Explain the human relations to the various agents, particularly noise and radiation

3. © 2008 by Nelson, a division of Thomson Canada Limited. 3 Learning Outcomes Discuss the management of physical agents Outline the actions of these agents on human physiology With the use of the chapter appendix, understand the methods of calculating noise levels and exposures

4. © 2008 by Nelson, a division of Thomson Canada Limited. 4 OH&S Important Terms Physical Agents: sources of energy that may cause injury or disease Ambient: all encompassing condition associated with a given environment; usually a composite of inputs from sources all around us Early Warning Change: a deterioration of hearing in the upper frequency – the earliest detectable sign of noise induced hearing loss

5. © 2008 by Nelson, a division of Thomson Canada Limited. 5 Noise Noise is defined as unwanted sound. The human hearing range of frequencies is approximately 20 to 20,000 Hz. The term threshold of hearing refers to the envelope or range of sound that the human ear can perceive or hear.

6. © 2008 by Nelson, a division of Thomson Canada Limited. 6 Noise The standards for the measurement of noise use the unit of a decibel (dB). Human hearing response is conditional on three characteristics: Frequency Duration Loudness

7. © 2008 by Nelson, a division of Thomson Canada Limited. 7 Types of Hearing Loss Noise can affect humans in three ways: physiologically, sociologically and psychologically. Physiologically there are two types of hearing loss: Conductive Sensorineural (most prevalent type)

8. © 2008 by Nelson, a division of Thomson Canada Limited. 8 Types of Hearing Loss Gradual hearing loss is known as temporary threshold shift (TTS). Permanent threshold shift (PTS) identifies a hearing disability that is permanent and may not be correctable.

9. © 2008 by Nelson, a division of Thomson Canada Limited. 9 Types of Hearing Loss Sociological Effects include: Vasoconstriction Hyper-reflexia

10. © 2008 by Nelson, a division of Thomson Canada Limited. 10 Types of Hearing Loss Human Psychology Effects: may include day to day noises often known as: selective hearing

11. © 2008 by Nelson, a division of Thomson Canada Limited. 11 Noise Exposure Standards The standards are based on worker exposure during a defined time frame. This relationship is known to as a dose (describing the amount of noise absorbed on an organ). Ontario allows for an 8 hour exposure of 90db(A).

12. © 2008 by Nelson, a division of Thomson Canada Limited. 12 Noise Exposure Noise exposure tests can be done utilizing a: Sound pressure level meter Octave band analyzer Dosimeter Audiometer

13. © 2008 by Nelson, a division of Thomson Canada Limited. 13 Noise Control The process for control follows the source-path-human strategies. The first strategy used to reduce noise is to make the source quieter. The second strategy or the path involves moving the worker away from the source or erecting sound barriers between the noise and worker, or both.

14. © 2008 by Nelson, a division of Thomson Canada Limited. 14 Noise Control The third strategy – human – involves the use of personal protective equipment. Least costly and is most commonly used.

15. © 2008 by Nelson, a division of Thomson Canada Limited. 15 Vibration Vibration refers to the oscillating motion of a particle or body moving about a reference position. Vibration is a health hazard for three reasons: It can cause whole body vibration (whole body) Segmental vibration (only parts of the body) Resonance (object reacts strongly to some frequency)

16. © 2008 by Nelson, a division of Thomson Canada Limited. 16 Thermal Stress Thermal stress conditions involve cold and hot temperature extremes usually coupled with high humidity. The human body takes in chemical energy (food) and converts it to mechanical energy (muscles) and heat known as homeostasis.

17. © 2008 by Nelson, a division of Thomson Canada Limited. 17 Thermal Stress Three methods of heat transfer that apply to the body: Conduction Convection Radiation

18. © 2008 by Nelson, a division of Thomson Canada Limited. 18 Radiation Radiation is divided into two distinct groups: Ionizing Nonionizing

19. © 2008 by Nelson, a division of Thomson Canada Limited. 19 Summary This chapter has focused on four physical agents commonly encountered in industry – noise, vibration, thermal stress and radiation. In most situations, however, simple prevention policies and programs are adequate for reducing and controlling worker exposure to physical agents.

20. © 2008 by Nelson, a division of Thomson Canada Limited. 20 Learning Outcomes After reading this chapter, you should be able to: Define the numerous terms relating to physical agents Explain the human reactions to the various agents, particularly noise and radiation Discuss the management of physical agents

21. © 2008 by Nelson, a division of Thomson Canada Limited. 21 Learning Outcomes Outline the actions of these agents on human physiology With the use of the chapter appendix, understand the methods of calculating noise levels and exposures