IE 331

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IE 331 Non-Ionizing Radiation and Lasers

• Carter J. Kerk, PhD, PE, CSP, CPE
• Industrial Engineering Program
• South Dakota School of Mines Technology

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Introduction

• Read Chapter 21 Non-Ionizing Radiation
• Radiation Control for Health Safety Act of 1960
• Several government standards
• OSHA
• CPSC
• FDA
• Consensus standards

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Non-Ionizing Radiation

• There are many sources of radiant energy sun,
  fire, microwaves, radio transmissions, atomic
  reactors, lamps, lasers.
• It takes 10 12 eV or more to break the bond of
  molecular elements. Sources of radiant energy
  below this level are considered non-ionizing.
• Sources above this level are considered
  ionizing (See Chapter 22). Ionizing radiation
  is any electromagnetic or particulate radiation
  capable of producing ions when it interacts with
  atoms or molecules.

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Types of Non-Ionizing Radiation

• Microwaves
• Ultraviolet Radiation
• Infrared Radiation
• High Intensity Visible Light
• Lasers
• VDTs
• Low Frequency Electric and Magnetic Fields
• lt 60 Hz ELF (Extremely Low Frequency), normally
  near high voltage transmission lines
• Cell Phones

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Electromagnetic Spectrum
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Hazards of Non-Ionizing Radiation

• Although energy levels do not affect molecular
  structure, non-ionizing radiation can affect
  biological tissue by changing energy levels in
  tissue molecules, often producing heat
• Heat easily effects certain tissue
• Eye has little blood circulation and little
  ability to remove heat through blood flow

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Absorption properties of the eye for
electromagnetic radiation
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Microwaves

• Uses Communication, navigation, medical
  diathermy, microwave ovens, drying equipment
• Frequencies 30 MHz 300 GHz
• Wavelengths 1 mm 10 m
• Waves lt 3 cm are absorbed in outer skin
• 3 10 cm penetrate from 1 mm 1 cm
• 25 200 cm penetrate to deeper tissues organs
• gt 200 cm, human tissue is transparent
• Absorbed radiation is primarily converted to
  heat, possibly to hazardous levels
• Greatest danger eyes cataracts, some
  pacemakers

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Microwave Controls

• Limit exposure and/or intensity
• Distance from source
• Shielding

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MicrowaveMeasurement Standards

• Measure microwaves with thermal or electrical
  detector instruments
• OSHA 29 CFR 1910.97
• Limit power density to 10 mW/cm2 for exposures gt
  0.1 hr
• For lt 0.1 hr, limit energy density to 1 mW-hr /
  cm2

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Microwave Standards

• ACGIH publishes limits

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Lasers

• LASER acronym for Light Amplification by
  Stimulated Emission of Radiation
• Intense, coherent, directional optical radiation
• Consists of an energy source, resonant cavity,
  and an active laser medium
• An assembly of electrical, mechanical, and
  optical components
• Becoming increasingly common welding,
  machining, measuring, alignment, checkout
  scanners, printers, medical applications, etc.

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Laser Hazards

• Some lasers are very dangerous and others not at
  all
• Hazard depends on intensity, wavelength, duration
  of exposure, and body part exposed
• With high energy levels, heat builds causing
  combustion

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Laser Hazards

• Lasers can fall in visible, ultraviolet and
  infrared ranges
• Greatest danger is visible range

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