1. Electromagnetic Radiation
Prepared by: Dr. Hussain Raufi

2. Contents:
 Electromagnetic Radiation
 Types of Photons in terms of Energy release
 Radiation and its types:
1. Non-ionizing Radiation
a. Ultraviolet radiation
b. Visible light, including lasers
c. Infrared Radiation
d. Microwave radiation
e. Electric and Magnetic Fields
f. Standards for control
2. Ionizing Radiation
a) Types of Exposures:
b) Effects
c) Dose-Response Relationship
d) Natural Background Radiation
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3. Electromagnetic Radiation :
 consisting of electromagnetic waves, including radio waves,
infrared, visible light, ultraviolet, x-rays, and gamma rays.
 Energy is calculated by Electron volt & the frequency is
calculated by Hz.
 Electromagnetic radiation is propagated through space in
the form of packets of energy called photons
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4. And Photons are of three types:
1. lower-energy photons, such as those associated with
electric and magnetic fields, have frequencies of 1–103
Hz
2. Photons in the intermediate-energy range (102–10 eV),
such as those associated with infrared and visible light,
have frequencies of 1012–1015 Hz
3. High energy photons are extremely penetrating and can
have effects far from their source; cosmic rays, x rays,
and gamma rays are the types of such energy
Only intermediate-range electromagnetic radiation can
be detected by the human senses 4

5. Radiation
Radiation: the process in which energy is emitted by something through intervening
medium or space, and absorbed by another body.
 Ionization: is the process of dissolving a particle or energy into ions.
 Radiation Types:
1. Non-ionizing Radiation: such as the lower & medium frequency range of
ultraviolet waves, as well as infrared waves, microwaves, and radio waves, do
not possess sufficient energy to be ionized while passing a medium.
2. Ionizing radiation: Higher-energy photons , such as cosmic rays, x rays, and
gamma rays, have sufficient energy that produces ionization while passing a medium.
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7. Non-Ionizing Radiation:
Ultraviolet radiation
 Source: Sun
 absorbent : atmosphere
 Protective layers: stratospheric ozone
 Artificial sources of UVR: These include the electric arcs used in lights,
welding torches, germicidal lamps, and tanning lamps.
 High short-term (acute) exposures to UVR can produce marked systemic
effects, including fever, nausea, and malaise
 Cumulative (chronic) effects include aging of the skin and premalignant or
malignant changes
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8. Cont..
Visible light, including lasers
 Effects: Direct and Indirect
 Insufficient lighting can result in a fall; excessive lighting, such as the bright
headlights of an oncoming car, can cause a crash.
 Laser used in wide range of applications: such as cutting, drilling, heat
treatment, entertainment (laser light shows), and surgery.
 However a minute quantities of laser light can burn a small hole in the retina
and permanently impair the vision of any person whose eyes are subjected to
the direct beam.
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9. Cont..
Infrared Radiation
 heat produced by a stove or by the radiant heating units used in many
dwellings.
 Infrared radiation does not penetrate deeply into tissues, but if it is not
controlled,
Microwave radiation
 Sources of microwave radiation include radar, radio and television transmitters,
satellite telecommunication systems, and microwave ovens
 Used in: industry to dry ,paint, inks, and synthetic rubber and to control insects
in stored grain. They are used in medicine to provide deep-heat therapy for the
relief of aching joints and sore muscles. 9

10. Cont..
Electric and Magnetic Fields
 Any home appliance that has an electric motor can be a source of a magnetic
field. Typical examples are refrigerators, clothes washers, and vacuum
cleaners
 investigators have claimed to have observed a link between childhood cancer
and electric and magnetic fields
 laboratory evidence in support of these findings has not been confirmed,
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11. Cont..
Standards for control
 primary source of guidelines for limiting exposures from sources of
nonionizing radiation is the International Commission on Nonionizing Radiation
Protection (ICNIRP)
 large uncertainties in knowledge about the health effects of a particular
agent,
 Similar guidance has been provided by the American Conference of
Governmental Industrial Hygienists (ACGIH, 2003). This includes
recommended limits for occupational exposures to lasers, static magnetic
fields, sub-radio-frequency magnetic fields, sub-radio-frequency and static
electric fields, radio-frequency and microwave radiation, light and
nearinfrared radiation, and ultraviolet radiation.
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13. Ionizing Radiation:
 Ionization, which ejects electrons from the atoms in the molecules includes
machine-produced x rays, discovered by Wilhelm Roentgen in 1895, and
alpha, beta, and gamma rays,
 The potential effects of radiation on cells can be divided into three
categories:
(1) at high doses, it can cause death;
(2) at lesser doses it can inhibit mitosis; and
(3) at any dose it can cause alterations in the genetic material of the cell
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14. Cont..
 Units have been developed for expressing the doses that result from exposures
to ionizing radiation
A. equivalent dose, the Sievert and milisievert (Sv, mSv ) express the dose to an
individual. Sv. Since this unit is far in excess of the doses usually encountered in
the workplace and the ambient environment
B. collective dose: it is calculated by multiplying the total number of people
exposed (expressed in units of persons) by their average individual dose.
the concept of collective dose, particularly in terms of assessing the risk to
large population groups who have received very small doses.
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15. Types of Exposures:
 External exposure: cause biological effects and depend on:
(1) The total dose,
(2) The percentage of the dose
(3) And the region of the body exposed
 Internal exposure: result from the presence or deposition of radioactive
materials in the body through ingestion or inhalation.
The potential harms depends on:
1. Type of material
2. Quantity
3. Time that remain in the body
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16. Cont..
 Effects of radiation exposure can be classified as:
1. Deterministic effects are those for which the severity of the effect varies
with the dose: such effects are generally associated with acute exposures
involving doses in the range of a Sv or more..
-Effects may include: cataracts, sterility, and tissue damage (for example,
erythema)
2. Stochastic effects, receipt of low doses over a long period of time and cause,
solid tumors and leukemia, anticipated follow some years.
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17. Dose-Response Relationships
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18. Natural Background Radiation
 For the world as a whole, the average total dose rate per person from natural
background radiation sources is estimated to be 2.2 to 2.4 mSv per year
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19. THANK YOU
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