Refers to those electromagnetic radiation
which are not energetic enough to cause
ionization in matter.
• Non-ionizing radiation refers to any type of
electromagnetic radiation that does not carry
enough energy per quantum to ionize atoms or
molecules—that is, to completely remove an
electron from an atom or molecule.
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• Non-Ionizing radiation (NIR) refers to radiative
energy that, instead of producing charged ions
when passing through matter, has sufficient energy
only for excitation.
• The NIR spectrum is divided into two main regions,
Optical Radiations and Electromagnetic Fields.
• The Optical can be further sub-divided into ultraviolet,
visible, and infra-red
• The Electromagnetic Fields are further divided into
radiofrequency (microwave, very high frequency and low
frequency radio wave)
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Non Ionizing Radiation source
• Non-ionizing radiation originates from various
• Natural origin (such as sunlight or lightning
discharges etc.) And
• Man-made (seen in wireless communications,
industrial, scientific and medical applications).
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• The optical radiations are centred around visible light;
those with higher energies are termed UV radiation
and those with lower energies IR radiation.
• Sources of UV radiation are the sun, arc welding, oxy-
gas welding, sun lamps, lasers (UV), sterilization
(germicidal) lamps, low pressure gas discharge lamps,
high pressure discharge lamps.
• Sources of IR radiation are from hot processes such as
steelmaking, glassmaking, welding, and also lasers (IR).
The application of laser as a coherent light source is
• Medical applications include UV and neonatal
phototherapy, surgical and therapy lasers,
physiotherapy heat lamps
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• Microwaves are used in telecommunications,
radar/satellite links, mobile phones, microwave ovens,
• RF is used in radio communications, visual display
units, television sets.
• Extremely low-frequency (ELF) electric and magnetic
fields (EMFs) surround electrical machinery, home
appliances, electric wiring, and high-voltage electrical
transmission lines and transformers.
• Medical applications include: microwave
hyperthermia, therapeutic and surgical diathermy, and
magnetic resonance imaging (MRI).
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NIR Biological Effects
• The basics of biological effects seen with NIR
relevant to human health is reviewed,
including the optical cause biological effects of
photochemical and heating; the
electromagnetic fields leads to surface
heating, electrical burn and shock.
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Electromagnetic Spectrum and
associated Biological Effects
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The Electromagnetic Spectrum
• Energy is proportional to frequency and is inversely
proportional to wavelength
• Inherent energy defines the transition between
ionizing and non-ionizing radiations
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The Electromagnetic Spectrum
Wavelength in Meters
Cosmic Rays Power
Ionizing Radiation Nonionizing Radiation
Energy - Electron VoltsHigh Low
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What is Non-ionizing Radiation?
Non-ionizing radiation is radiation that does
not "ionize an atom"
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Waves01:45:57 PM 14
• Ultraviolet light
• Visible light
• Infrared radiation
• Radio & TV
• Power transmission
• Ultraviolet – Black light – induce fluorescence in
• Vision – very small portion that animals use to
process visual information
• Heat – infrared – a little beyond the red
• Radio waves – beyond infrared
• Micro waves
• Electrical power transmission – 60 cycles per
second with a wave length of 1 to 2 million
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• Sun light
Most harmful UV is absorbed by the atmosphere
– depends on altitude
• Fluorescent lamps
• Electric arc welding - can damage the eye
Sources: Sun, mercury lamps, welding, lasers, pest
control (fly lamps), fluorescent lighting
• Target organs: Skin, Eyes, Immune System
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• The near Ultraviolet is absorbed very strongly in the surface
layer of the skin by electron transitions. As you go to higher
energies, the ionization energies for many molecules are
reached and the more dangerous photoionization
processes take place.
• Sunburn is primarily an effect of UV, and ionization
produces the risk of skin cancer.
• The ozone layer in the upper atmosphere is important for
human health because it absorbs most of the harmful
ultraviolet radiation from the sun before it reaches the
• The higher frequencies in the ultraviolet are ionizing
radiation and can produce harmful physiological effects
ranging from sunburn to skin cancer.
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Biological Effect [UV]
• Aging of the skin
• Reddening of the skin (erythema)
• Skin cancer upon prolonged exposures
• Corneal injury
• Photosensitization (with some chemicals)
• Benefits – Induces production of Vitamin D in
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• The quantum energy of infrared photons is in the range 0.001
to 1.7 eV which is in the range of energies separating the
quantum states of molecular vibrations.
• Infrared is absorbed more strongly than microwaves, but less
strongly than visible light. The result of infrared absorption is
heating of the tissue since it increases molecular vibrational
• Infrared radiation does penetrate the skin further than visible
light and can thus be used for photographic imaging of
subcutaneous blood vessels.
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• SOURCES: most are thermal sources (plasma
torches, halogen lamps)
• Target Organs: skin and eyes
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Infrared Radiation Effects
Energy between 750 nm to 0.3 cm
The energy of heat – Heat is the transfer of energy
Can damage – cornea, iris, retina and lens of the eye
(glass workers – “glass blower’s cataract”)
Primarily thermal in nature
Skin: heats/burn surface of the skin and tissues
Eyes: Can damage retina and cornea, cause
Easiest to avoid: you can see it & feel it
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– Heating and drying
– Air traffic control
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Microwaves & Radio Waves
• Energy between 0.1 cm to 1 kilometer
• Varity of industrial and home uses for
heating and information transfer (radio, TV,
• Produced by molecular vibration in solid
bodies or crystals
• Health effects – heating, cataracts
• Long-term effects being studied
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The quantum energy of microwave photons is in the range
0.00001 to 0.001 eV which is in the range of energies
separating the quantum states of molecular rotation and
The interaction of microwaves with matter other than metallic
conductors will be to rotate molecules and produce heat as
result of that molecular motion. Conductors will strongly
absorb microwaves and any lower frequencies because they
will cause electric currents which will heat the material.
Most matter, including the human body, is largely transparent to
microwaves. High intensity microwaves, as in a microwave
oven where they pass back and forth through the food millions
of times, will heat the material by producing molecular
rotations and torsions.
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• The wavelength of microwave radiation
ranges from about 10 microns to 1 meter
• Microwaves have very low energies and very
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• Microwave radiation has many
– Cellular phones
– Highway speed control
– Food preparation
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WHY EMF IS HARMFUL?WHY EMF IS HARMFUL?
A. Alters permeability of the blood brain barrier thus
allows the transfer of toxins from blood to brain.
B. Enhances the appearance of many diseases.
C. Alters biological cycles.
D. Alters hormone levels,
E. Cause chromosomal damage, infertility.
F. Causes cataracts and eye problems.
G. Alters moods.
H. Alters learning ability
I. Release of more adrenaline in most people within 15
J. Increases rate of cancer-cell division
K. Leukemia and other cancers increase greatly among
people living near overhead power cables