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  1. 1. RADIATION A natural phenomenon you shouldn’t be afraid of!!
  2. 2. SOME QUICK FACTS TO HELP YOU DRIVE OUT YOUR RADIATION FEAR <ul><li>THINGS YOU SHOULD KNOW </li></ul><ul><li>Radiation is a natural phenomenon. </li></ul><ul><li>Not all types of radiations are harmful. </li></ul><ul><li>The harmful radiations harm us only if we are in contact with them for a long period of time and that too when they are in excess. </li></ul><ul><li>The world has the technology to control and cope up with the effects of radiation. </li></ul><ul><li>CAUSES OF DEATH </li></ul>Death Risk - Cause Death Risk – 40 Year Old All causes 1 per 500 Smoker –10 a day 1 per 2,000 Road accidents 1 per 5,000 Home accidents 1 per 10,000 Work accidents 1 per 20,000 All radiations 1 per 27,500 Medical Radiations 1 per 240,000
  3. 3. WHAT IS RADIATION? <ul><li>Radiation is a process in which a body emits energy that propagates through a medium, or through empty space, to be absorbed by other bodies. </li></ul><ul><li>A body which emits radiation is said to be a radioactive body. </li></ul>Radiation is everywhere around us.
  4. 4. TYPES OF RADIATION <ul><li>IONIZING RADIATION </li></ul><ul><li>This kind of radiation, on interaction with matter can produce charged particles called ions. </li></ul><ul><li>Some of these rays in excess can be harmful. These are even used for medical purposes. </li></ul><ul><li>Examples include X-rays, cosmic rays, gamma rays. </li></ul><ul><li>NON-IONIZING RADIATION </li></ul><ul><li>This kind of radiation cannot produce ions. </li></ul><ul><li>These rays aren’t directly harmful. In fact , our lives depend heavily on these for survival </li></ul><ul><li>Examples include infrared waves, radio waves, ultraviolet waves etc. </li></ul>
  5. 5. LOCATION OF THESE RADIATIONS IN THE ELECTROMAGNETIC SPECTRUM ELECTROMAGNETIC SPECTRUM 10 -14 10 -12 10 -10 10 -8 10 -6 10 -4 10 -2 1 10 2 10 4 10 6 10 8 Wavelength in Meters 10 10 10 8 10 6 10 4 10 2 1 10 -2 10 -4 10 -6 10 -8 10 -10 10 -12 10 -14 Broadcast Short wave TV FM Radar Infrared Near Far Visible Ultraviolet X Rays Gamma Rays Cosmic Rays Power Transmission Ionizing Radiation Non-ionizing Radiation Energy - Electron Volts High Low
  6. 6. NON-IONIZING RADIATION <ul><li>SOURCES- </li></ul><ul><li>Ultraviolet light </li></ul><ul><li>Visible light </li></ul><ul><li>Infrared radiation </li></ul><ul><li>Microwaves </li></ul><ul><li>Radio & TV </li></ul><ul><li>Power transmission </li></ul>Radiant energy of the sun is due to visible light
  7. 7. Ultraviolet radiation <ul><li>SOURCES </li></ul><ul><li>Sun light </li></ul><ul><li>Fluorescent lamps </li></ul><ul><li>Electric arc welding </li></ul><ul><li>Germicidal lamps </li></ul><ul><li>EFFECTS OF IT </li></ul><ul><li>High ultraviolet – kills bacterial and other infectious agents. </li></ul><ul><li>High dose causes - sun burn – increased risk of skin cancer. </li></ul><ul><li>Pigmentation that results in suntan . To prevent this, we can use suntan lotions which contain chemicals that absorb UV radiation. </li></ul><ul><li>Reaction in the skin to produce Vitamin D that prevents rickets. </li></ul><ul><li>Strongly absorbed by air – thus the danger of hole in the atmosphere. </li></ul>This image of the sun was taken with a filter which shows radiation only in the extreme ultraviolet (UV) range of the spectrum, shown as blue
  8. 8. <ul><li>Visible Light </li></ul><ul><li>Energy between 400 and 750 nm </li></ul><ul><li>High energy – bright light produces of number of adaptive responses esepecially vision. </li></ul><ul><li>Standards are set for the intensity of light in the work place </li></ul><ul><li>Infrared Radiation </li></ul><ul><li>Energy between 750 nm to 0.3 cm </li></ul><ul><li>(1 nm (nanometer)= 10 -9 meters) </li></ul><ul><li>The energy of heat – Heat is the transfer of energy. </li></ul><ul><li>Radiated in the form of heat </li></ul>Visible light helps us to see the world around us A cat when seen through an infrared camera
  9. 9. IONIZING RADIATION <ul><li>DEFINITION </li></ul><ul><li>Radiation capable for producing ions when interacting with matter – in other words enough energy to remove an electron from an atom. </li></ul><ul><li>SOURCES </li></ul><ul><li>X-rays </li></ul><ul><li>Radioactive material produce alpha, beta, and gamma radiation </li></ul><ul><li>Cosmic rays from the sun and space </li></ul>A diagram showing how ionizing radiations produce ions.
  10. 10. Penetration powers of different radiations Paper Wood Concrete Alpha Beta Gamma Energy Low Medium High
  11. 11. <ul><li>ALPHA RADIATION </li></ul><ul><li>Two neutrons and two protons </li></ul><ul><li>Charge of +2 </li></ul><ul><li>Emitted from nucleus of radioactive atoms </li></ul><ul><li>Transfer energy in very short distances </li></ul><ul><li>Penetrating power is very low, so, can be shielded by paper or layer of skin </li></ul><ul><li>Not an external hazard </li></ul><ul><li>Internal exposure (upon consumption) can cause accumulation in bone, kidney, liver, lung, spleen tissues causing local damage </li></ul><ul><li>BETA RADIATION </li></ul><ul><li>Small electrically charged particles similar to electrons </li></ul><ul><li>Charge of -1 </li></ul><ul><li>Ejected from nuclei of radioactive atoms </li></ul><ul><li>Emitted with various kinetic energies </li></ul><ul><li>Penetrating power is moderate, so can be shielded by wood, body penetration 0.2 to 1.3 cm. </li></ul><ul><li>If allowed to remain on skin for a long time, these may cause skin injuries. Clothing can protect us from this. </li></ul>
  12. 12. <ul><li>GAMMA RADIATION </li></ul><ul><li>Electromagnetic photons or radiation (identical to x-rays except for source) </li></ul><ul><li>Emitted from nucleus of radioactive atoms – spontaneous emission </li></ul><ul><li>Produced from radioactive materials. </li></ul><ul><li>X-RAYS </li></ul><ul><li>Overlap with gamma-rays </li></ul><ul><li>Electromagnetic photons or radiation </li></ul><ul><li>Produced from orbiting electrons or free electrons – usually machine produced </li></ul><ul><li>Discovered in 1895 by Roentgen </li></ul><ul><li>These are highly penetrating, thus, require extensive shielding </li></ul><ul><li>These are electromagnetic radiations, visible like light, the only difference being in the energy possessed </li></ul><ul><li>These act as external radiation hazards </li></ul>This image shows an X-ray image of the hand of wife of W. Roentgen, the discoverer of X-ray.
  13. 13. EFFECTS OF RADIATIONS ON HEALTH <ul><li>Only ionizing radiation has effects on health, that too, when someone is excessively exposed to them. </li></ul><ul><li>HOW DOES IONIZING RADIATION HARM US? </li></ul><ul><li>Ionising radiation can kill or change the nature of living cell due to its ionizing nature. </li></ul><ul><li>FACTORS EFFECTING RADIATION EFFECTS- </li></ul><ul><li>The type of radiation. </li></ul><ul><li>The type of body tissue or body organ that absorbs the radiation. </li></ul><ul><li>The total amount of energy absorbed. </li></ul>
  14. 14. FREQUENTLY ASKED QUESTIONS <ul><li>QUESTION ONE- </li></ul><ul><li>Does the body have no mechanisms to repair the damage? </li></ul><ul><li>Answer- Since we have evolved with a certain level of naturally occurring ionizing radiation from cosmic radiation, radioactive materials in the earth, we do have mechanisms to repair damage. </li></ul>
  15. 15. <ul><li>QUESTION TWO- </li></ul><ul><li>Does radiation cause cancer? </li></ul><ul><li>Answer- The mechanisms for cancer occurring are poorly understood at the moment. One theory is that the ionising radiation affects the DNA material within us – our genetic make-up. Our DNA contains genetic instructions which control the operation and reproduction of the cells. If ionisations caused by ionising radiations alter these instructions in the DNA, there is a “chance “ that cancer will develop . However, it is a fact that genetic damage is caused by a large exposure to radiation. </li></ul>
  16. 16. <ul><li>QUESTION THREE- </li></ul><ul><li>In what units is radiation measured? </li></ul><ul><ul><li>Answer- </li></ul></ul><ul><ul><li>Radioactivity (no. of radiations per second)- Bequerel (Bq) </li></ul></ul><ul><ul><li>Amount of Exposure – X (coul/kg) </li></ul></ul><ul><ul><li>Absorbed Dose (amount of energy absorbed)– Gray (Gy) </li></ul></ul><ul><ul><li>Equivalent Dose (makes different sources of radiation equivalent)– Sievert (Sv) </li></ul></ul><ul><li>QUESTION FOUR- </li></ul><ul><li>What is background radiation? </li></ul><ul><li>Answer- Background radiation is radiation that is naturally occurring. </li></ul>
  17. 17. <ul><li>QUESTION FOUR- Tell me the natural sources of radiation </li></ul>Source Annual Dose (  Sv) Radon and thoron gas from rocks and soil 800 Gamma rays from ground 400 Carbon and potassium in your body 370 Cosmic rays at ground level 300 Total = 1870
  18. 18. <ul><li>QUESTION FOUR- Tell me the man-made sources of radiation </li></ul>Annual Dose (  Sv) Medical uses – x-rays, etc. 250 Chernobyl 50 Fall-out from weapons testing 10 Job (average) 5 Nuclear industry (e.g. waste) 2 Others (TV, aeroplane trips, etc.) 11 Total = 328
  19. 19. <ul><li>QUESTION FIVE- What is meant by quality factor? </li></ul><ul><li>Different types of radiation have different effects on living cells </li></ul><ul><li>Even though the same type of tissue may receive the same dose, the biological effects of different radiations will be different. To take this into account, a quality factor is assigned to all types of radiation. </li></ul><ul><li>The quality factor, Q, allows the effects that different radiations have on living cells to be compared. </li></ul>The quality factor for each type of radiation is shown below: From this it can be seen that alpha radiation is the most ionising radiation out of the three types. Radiation Quality Factor (Q) Alpha particles 20 Beta particles 1 Gamma rays 1