RADIATION A natural phenomenon you shouldn’t be afraid of!!
SOME QUICK FACTS TO HELP YOU DRIVE OUT YOUR RADIATION FEAR
THINGS YOU SHOULD KNOW
Radiation is a natural phenomenon.
Not all types of radiations are harmful.
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.
The world has the technology to control and cope up with the effects of radiation.
CAUSES OF DEATH
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
WHAT IS RADIATION?
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.
A body which emits radiation is said to be a radioactive body.
Radiation is everywhere around us.
TYPES OF RADIATION
This kind of radiation, on interaction with matter can produce charged particles called ions.
Some of these rays in excess can be harmful. These are even used for medical purposes.
Examples include X-rays, cosmic rays, gamma rays.
This kind of radiation cannot produce ions.
These rays aren’t directly harmful. In fact , our lives depend heavily on these for survival
Examples include infrared waves, radio waves, ultraviolet waves etc.
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
Radio & TV
Radiant energy of the sun is due to visible light
Electric arc welding
EFFECTS OF IT
High ultraviolet – kills bacterial and other infectious agents.
High dose causes - sun burn – increased risk of skin cancer.
Pigmentation that results in suntan . To prevent this, we can use suntan lotions which contain chemicals that absorb UV radiation.
Reaction in the skin to produce Vitamin D that prevents rickets.
Strongly absorbed by air – thus the danger of hole in the atmosphere.
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
Energy between 400 and 750 nm
High energy – bright light produces of number of adaptive responses esepecially vision.
Standards are set for the intensity of light in the work place
Energy between 750 nm to 0.3 cm
(1 nm (nanometer)= 10 -9 meters)
The energy of heat – Heat is the transfer of energy.
Radiated in the form of heat
Visible light helps us to see the world around us A cat when seen through an infrared camera
Radiation capable for producing ions when interacting with matter – in other words enough energy to remove an electron from an atom.
Radioactive material produce alpha, beta, and gamma radiation
Cosmic rays from the sun and space
A diagram showing how ionizing radiations produce ions.
Penetration powers of different radiations Paper Wood Concrete Alpha Beta Gamma Energy Low Medium High
Two neutrons and two protons
Charge of +2
Emitted from nucleus of radioactive atoms
Transfer energy in very short distances
Penetrating power is very low, so, can be shielded by paper or layer of skin
Not an external hazard
Internal exposure (upon consumption) can cause accumulation in bone, kidney, liver, lung, spleen tissues causing local damage
Small electrically charged particles similar to electrons
Charge of -1
Ejected from nuclei of radioactive atoms
Emitted with various kinetic energies
Penetrating power is moderate, so can be shielded by wood, body penetration 0.2 to 1.3 cm.
If allowed to remain on skin for a long time, these may cause skin injuries. Clothing can protect us from this.
Electromagnetic photons or radiation (identical to x-rays except for source)
Emitted from nucleus of radioactive atoms – spontaneous emission
Produced from radioactive materials.
Overlap with gamma-rays
Electromagnetic photons or radiation
Produced from orbiting electrons or free electrons – usually machine produced
Discovered in 1895 by Roentgen
These are highly penetrating, thus, require extensive shielding
These are electromagnetic radiations, visible like light, the only difference being in the energy possessed
These act as external radiation hazards
This image shows an X-ray image of the hand of wife of W. Roentgen, the discoverer of X-ray.
EFFECTS OF RADIATIONS ON HEALTH
Only ionizing radiation has effects on health, that too, when someone is excessively exposed to them.
HOW DOES IONIZING RADIATION HARM US?
Ionising radiation can kill or change the nature of living cell due to its ionizing nature.
FACTORS EFFECTING RADIATION EFFECTS-
The type of radiation.
The type of body tissue or body organ that absorbs the radiation.
The total amount of energy absorbed.
FREQUENTLY ASKED QUESTIONS
Does the body have no mechanisms to repair the damage?
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.
Does radiation cause cancer?
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.
In what units is radiation measured?
Radioactivity (no. of radiations per second)- Bequerel (Bq)
Amount of Exposure – X (coul/kg)
Absorbed Dose (amount of energy absorbed)– Gray (Gy)
Equivalent Dose (makes different sources of radiation equivalent)– Sievert (Sv)
What is background radiation?
Answer- Background radiation is radiation that is naturally occurring.
QUESTION FOUR- Tell me the natural sources of radiation
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
QUESTION FOUR- Tell me the man-made sources of radiation
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
QUESTION FIVE- What is meant by quality factor?
Different types of radiation have different effects on living cells
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.
The quality factor, Q, allows the effects that different radiations have on living cells to be compared.
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