Non-Ionizing Radiation CHEM 605 Fall 2005

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Non-Ionizing RadiationCHEM 605Fall 2005

• Mary J. Handy
• Health Physicist, Laser Safety Officer
• Dept. of Radiological and Environmental Management

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Topics

• Definitions
• Types of Non-Ionizing Radiation Sources
• Lasers
• Radiofrequency/Electromagnetic Energy (RF/EME)
• Magnets

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Definitions

• Electromagnetic radiation
• Energy which consists of waves of electric and
  magnetic energy moving together (i.e., radiating)
  through space at the speed of light. Taken
  together, all forms of electromagnetic energy are
  referred to as the electromagnetic "spectrum.
• Non-Ionizing Radiation
• Radiation without sufficient energy to strip
  electrons from the orbit of an atom (unlike
  ionizing radiation), yet enough energy to excite
  orbital electrons.

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Definitions

• Threshold Limit Values (TLVs)
• Time Weighted Average (TLV-TWA) exposure limit
  at which a worker can be exposed for 8-hr. work
  days over a 40-hr. work week with no expected
  adverse effect.
• Short-Term Exposure Limit (TLV-STEL) short term
  exposure limit at which a worker can be exposed
  with no expected
• Irritation
• Chronic or reversible tissue damage, or
• Narcosis of significant() degree.
• Ceiling (C) exposure limit at which
  concentration should not be exceeded at any part
  of the working exposure.

as stated in ACGIH Publication TLVs and BEIs
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Laser Awareness
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What is a LASER?

• LASER
• Light Amplification by Stimulated Emission of
  Radiation

Optical Cavity
Lasing Medium
Emitted Wavelength
Partially Reflecting Mirror
Fully Reflecting Mirror
Pumping System
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Some laser applications

• Research/Teaching (e.g. spectroscopy, LIDAR)
• Entertainment (e.g. light shows, cd players)
• Medical (e.g. lasik surgery, retinal
  phototherapy)
• Manufacturing (e.g. welding, cutting,
  lithography)
• Construction (e.g. laser levels)
• Military (e.g. Airborne Laser, Tactical
  High-Energy Laser)
• Office (e.g. laser printers, laser pointers)

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Laser Hazard Classification Scheme

• Class 1 normally cannot produce a hazard.
• Class 2 may present some potential for hazard if
  viewed directly for extended periods of time.
• Class 3a normally would not produce a hazard if
  viewed for only momentary periods with the
  unaided eye.
• Class 3b can produce a hazard if viewed
  directly or specular (i.e. mirror-like)
  reflection.
• Class 4 can produce a hazard not only from
  direct or specular reflections, but also from a
  diffuse reflection. In addition, such lasers may
  produce fire hazards and skin hazards.
• Class 3b and 4 lasers are required to register
  with laser safety program.

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Can I be in a room with a Class IIIb or IV laser
if I havent had Laser Safety Training?

• Yes, as long as
• The laser is not in operation, OR
• The laser system is totally enclosed (where the
  Nominal Hazard Zone (NHZ) is the laser system, OR
• The laser system is surrounded by barriers (which
  would be the NHZ) and you are on the outside of
  the NHZ, OR
• You are authorized to be in the NHZ, are wearing
  the appropriate laser safety equipment, AND are
  NOT operating the laser.

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Controlled area posting
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Beam Hazards

• Eye Damage
• Thermal
• Photochemical
• Photoacoustic
• Skin Damage
• range from mild reddening (erythema) to
  blistering
• depend upon exposure dose rate, exposure dose,
  and conduction of heat away from the site of
  absorption
• possible carcinogenic effects

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Eye Protection
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Eye Protection (continued)

• All laser safety eyewear should be stamped with
  the optical density (OD) at a particular
  wavelength.
• Standard laboratory goggles will not provide the
  protection needed.
• Laser safety eyewear for one laser system does
  not necessarily protect you from the laser of
  another system.

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NON-BEAM HAZARDSIndustrial Hygiene Hazards

• Compressed Gases
• Laser Generated Air Contaminants (LGACs)
• Cryogenic Materials
• Toxic and Carcinogenic Materials
• Noise
• Ionizing Radiation
• From high voltage power supplies (gt15kV)
• Adequate Ventilation

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NON-BEAM HAZARDSOther Hazards

• Explosion Hazards (e.g. high pressure arc lamps,
  capacitor banks)
• Optical Hazards (e.g. plasma)
• Electrical Hazards (e.g. capacitor banks, high
  voltage power supplies)
• Fire Hazards (e.g. beam enclosures, components in
  electrical circuits, LGACs)

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LASER LABORATORY SAFETYANSI Z136.1-2000

• Engineering Controls
• Incorporated into laser design or system
• Preferred over procedural and administrative
  control measures
• Administrative and Procedural Controls
• Methods or instructions which specify work
  practices

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RF/EME Awareness
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RF Sources

• Communication (radio TV broadcasting, cell
  phone, pagers, satellite, amateur, etc.)
• Microwave ovens
• Power lines
• Physical therapy (RF Diathermy)
• Lasers

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Biological Effects

• Radiofrequency Ranges (10 kHz to 300 GHz)
• Effects only possible at ten times the
  permissible exposure limit
• Heating of the body
• Cataracts
• Developing fetus is at no greater risk than
  mother
• Two areas of the body, the eyes and the testes,
  are particularly vulnerable to RF heating because
  of the relative lack of available blood flow to
  dissipate the excessive heat load.
• Cancer? Conflicting studies, no delectable
  studies.

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FCC Limits for Occupational/ Controlled Exposure
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Power Density Example
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Postings
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NOTICEGUIDELINES FOR WORKING IN RADIOFREQUENCY
ENVIRONMENTS

• All personnel should have electromagnetic energy
  (EME) awareness training.
• All personnel entering this site must be
  authorized.
• Obey all posted signs.
• Assume all antennas are active.
• Before working on antennas, notify owners and
  disable appropriate transmitters.
• Maintain minimum 3 feet clearance from all
  antennas.
• Do not stop in front of antennas.
• Use personal RF monitors while working near
  antennas.
• Never operate transmitters without shields during
  normal operation.
• Do not operate base station antennas in equipment
  room.

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Magnet Awareness
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Topics

• Definitions
• Types of Magnets
• Potential Biological Effects
• Exposure Limits (source 2005 ACGIH TLVs and
  BEIs)
• Protective Measures
• Postings
• REM Contact List

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Types of Magnets

• Electromagnets magnets where the magnetic field
  is generated by the flow of electric current
• Permanent Magnets magnetic without electric
  current

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Electromagnets (examples)

• MRIs (magnetic resonance imaging) formally
  known as NMRs (nuclear magnetic resonance)
• Cathode ray tubes
• Charged particle beams
• Mass spectrometers
• Solenoid valves
• Magnetic levitation trains
• Doorbells

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Potential Biological Effects

• Could effect electromagnetic devices (e.g.
  cardiac pacemakers)
• Attracts ferrous objects, both inside and outside
  body (i.e. flying metal objects!)
• Occurring at 2 T or greater (static magnets)
• Nauseousness, vertigo, magnetophosphenes (i.e.
  flickering light in eyes)
• Induction of electrical potential within blood

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Static Magnetic Fields TLVs (Exposure Limits)
1 tesla (T) 104 gauss (G)
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Protective Measures

• Exposure Reduction
• Time reduce time around significant magnetic
  fields
• Distance inverse square law applies, a little
  more distance goes a long way!
• Shielding can be expensive, not typically
  cost-effective.
• Safety
• Heed warnings regarding pacemakers or other
  electromagnetic devices, metallic implants
• Eliminate loose paramagnetic objects

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Postings
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REM Contact List

• REM Main Number- 46371
• Jim Schweitzer- 42350
• Radiation Safety Officer and Director, REM
• Mary Handy- 42721
• Laser Safety Officer / Health Physicist
• Mark Pflug- 42693
• Health Physicist
• Deb Smith- 40205
• Health Physicist