BIOLOGICAL EFFECTS OF RADIATION USHA YADAV.pptxSubamProjects
Basic of human body
What is biological effect of radiation
How radiation can cause biological damage
Factors affecting biological effects
What are classes different biological effects caused by radiation
Acute radiation syndrome
Partial body effects
Cancer and genetic risk
BIOLOGICAL EFFECTS OF RADIATION USHA YADAV.pptxSubamProjects
Basic of human body
What is biological effect of radiation
How radiation can cause biological damage
Factors affecting biological effects
What are classes different biological effects caused by radiation
Acute radiation syndrome
Partial body effects
Cancer and genetic risk
14 Effects of Radiation on the Human Body and the Environment.pdfMansoor Ahmad
Almost every day, you come into contact with or are exposed to small doses of radiation. This radiation is produced by both man-made and natural sources, such as the sun's rays (such as microwave ovens and medical X-rays).But a radiation event, such as a nuclear power plant disaster, can expose you to high, dangerous levels.
This is a presentation by Dada Robert in a Your Skill Boost masterclass organised by the Excellence Foundation for South Sudan (EFSS) on Saturday, the 25th and Sunday, the 26th of May 2024.
He discussed the concept of quality improvement, emphasizing its applicability to various aspects of life, including personal, project, and program improvements. He defined quality as doing the right thing at the right time in the right way to achieve the best possible results and discussed the concept of the "gap" between what we know and what we do, and how this gap represents the areas we need to improve. He explained the scientific approach to quality improvement, which involves systematic performance analysis, testing and learning, and implementing change ideas. He also highlighted the importance of client focus and a team approach to quality improvement.
2024.06.01 Introducing a competency framework for languag learning materials ...Sandy Millin
http://sandymillin.wordpress.com/iateflwebinar2024
Published classroom materials form the basis of syllabuses, drive teacher professional development, and have a potentially huge influence on learners, teachers and education systems. All teachers also create their own materials, whether a few sentences on a blackboard, a highly-structured fully-realised online course, or anything in between. Despite this, the knowledge and skills needed to create effective language learning materials are rarely part of teacher training, and are mostly learnt by trial and error.
Knowledge and skills frameworks, generally called competency frameworks, for ELT teachers, trainers and managers have existed for a few years now. However, until I created one for my MA dissertation, there wasn’t one drawing together what we need to know and do to be able to effectively produce language learning materials.
This webinar will introduce you to my framework, highlighting the key competencies I identified from my research. It will also show how anybody involved in language teaching (any language, not just English!), teacher training, managing schools or developing language learning materials can benefit from using the framework.
Welcome to TechSoup New Member Orientation and Q&A (May 2024).pdfTechSoup
In this webinar you will learn how your organization can access TechSoup's wide variety of product discount and donation programs. From hardware to software, we'll give you a tour of the tools available to help your nonprofit with productivity, collaboration, financial management, donor tracking, security, and more.
How to Split Bills in the Odoo 17 POS ModuleCeline George
Bills have a main role in point of sale procedure. It will help to track sales, handling payments and giving receipts to customers. Bill splitting also has an important role in POS. For example, If some friends come together for dinner and if they want to divide the bill then it is possible by POS bill splitting. This slide will show how to split bills in odoo 17 POS.
Instructions for Submissions thorugh G- Classroom.pptxJheel Barad
This presentation provides a briefing on how to upload submissions and documents in Google Classroom. It was prepared as part of an orientation for new Sainik School in-service teacher trainees. As a training officer, my goal is to ensure that you are comfortable and proficient with this essential tool for managing assignments and fostering student engagement.
The Art Pastor's Guide to Sabbath | Steve ThomasonSteve Thomason
What is the purpose of the Sabbath Law in the Torah. It is interesting to compare how the context of the law shifts from Exodus to Deuteronomy. Who gets to rest, and why?
The Roman Empire A Historical Colossus.pdfkaushalkr1407
The Roman Empire, a vast and enduring power, stands as one of history's most remarkable civilizations, leaving an indelible imprint on the world. It emerged from the Roman Republic, transitioning into an imperial powerhouse under the leadership of Augustus Caesar in 27 BCE. This transformation marked the beginning of an era defined by unprecedented territorial expansion, architectural marvels, and profound cultural influence.
The empire's roots lie in the city of Rome, founded, according to legend, by Romulus in 753 BCE. Over centuries, Rome evolved from a small settlement to a formidable republic, characterized by a complex political system with elected officials and checks on power. However, internal strife, class conflicts, and military ambitions paved the way for the end of the Republic. Julius Caesar’s dictatorship and subsequent assassination in 44 BCE created a power vacuum, leading to a civil war. Octavian, later Augustus, emerged victorious, heralding the Roman Empire’s birth.
Under Augustus, the empire experienced the Pax Romana, a 200-year period of relative peace and stability. Augustus reformed the military, established efficient administrative systems, and initiated grand construction projects. The empire's borders expanded, encompassing territories from Britain to Egypt and from Spain to the Euphrates. Roman legions, renowned for their discipline and engineering prowess, secured and maintained these vast territories, building roads, fortifications, and cities that facilitated control and integration.
The Roman Empire’s society was hierarchical, with a rigid class system. At the top were the patricians, wealthy elites who held significant political power. Below them were the plebeians, free citizens with limited political influence, and the vast numbers of slaves who formed the backbone of the economy. The family unit was central, governed by the paterfamilias, the male head who held absolute authority.
Culturally, the Romans were eclectic, absorbing and adapting elements from the civilizations they encountered, particularly the Greeks. Roman art, literature, and philosophy reflected this synthesis, creating a rich cultural tapestry. Latin, the Roman language, became the lingua franca of the Western world, influencing numerous modern languages.
Roman architecture and engineering achievements were monumental. They perfected the arch, vault, and dome, constructing enduring structures like the Colosseum, Pantheon, and aqueducts. These engineering marvels not only showcased Roman ingenuity but also served practical purposes, from public entertainment to water supply.
Operation “Blue Star” is the only event in the history of Independent India where the state went into war with its own people. Even after about 40 years it is not clear if it was culmination of states anger over people of the region, a political game of power or start of dictatorial chapter in the democratic setup.
The people of Punjab felt alienated from main stream due to denial of their just demands during a long democratic struggle since independence. As it happen all over the word, it led to militant struggle with great loss of lives of military, police and civilian personnel. Killing of Indira Gandhi and massacre of innocent Sikhs in Delhi and other India cities was also associated with this movement.
2. Learning outcomes
After lecture you should know:
Physical bases of ionizing radiation
Measurement units for activity and exposure doses
Environmental and medical sources of ionizing radiation
Acute and chronic health effects of ionizing radiation to
human body
Principles of protection from ionizing radiation
3. Radiation is energy carried by waves or a stream of particles
Electromagnetic radiation
(photons)
Heat waves
Radiowaves
Infrared light
Visible light
Ultraviolet light
X rays
Gamma rays
Radiation emitted by radioactive
materials
Alpha particles
Beta particles
Protons
Neutrons
4. Ionizing radiation is radiation with enough energy so
that during an interaction with an atom, it can remove
tightly bound electrons from the orbit of an atom,
causing the atom to become charged or ionized
6. Beta particles
Beta minus decay happens
when a neutron within an
atom's nucleus transforms into
a proton and an electron and
an antineutrino are ejected out
of the nucleus of an atom. For
a beta plus decay a proton
transforms to a neutron and a
positron (similar to an electron
but with a positive charge) and
a neutrino are ejected out of
the nucleus
7. Neutrons
The neutron is an indirectly
ionizing particle. It is
indirectly ionizing because
it does not carry an
electrical charge.n
8. X rays and gamma waves
Longer wave length, lower frequency waves (heat and radio) have less
energy than shorter wave length, higher frequency waves (X and
gamma rays)
9. Isotopes
Atoms with the same number
of protons and different
number of neutrons are
called ISOTOPES. An isotope
may be defined as one or two
or more forms of the same
element having the same
atomic number (Z), differing
mass numbers (A), and the
same chemical properties
10. Activity
The activity of a radioisotope is simply a measure of how many atoms
undergo radioactive decay per a unit of time.
The SI unit for measuring the rate of nuclear transformations is the
becquerel (Bq). The becquerel is defined as 1 radioactive disintegration
per second.
The old unit for this is the curie (Ci), in honour of Pierre and Marie
Curie who discovered radium and polonium. The curie is based on the
activity of 1 gram of radium-226, i.e. 3.7 x 1010 radioactive
disintegrations per second.
11. Why is ionizing radiation dangerous?
When atoms in living cells become ionized one of three things usually
happen – the cell dies, the cell repairs itself, or the cell mutates
incorrectly and can become cancerous. Not all cells are affected by
ionizing radiation in the same way. The cells that reproduce the most
and are the least specialized are the most likely to be affected by
ionizing radiation, for example those in a forming fetus
12. Health effects of Ionizing radiation
• Acute health effects:
• Acute radiation syndrome (ARS) or radiation poisoning
• Acute radiation burns (cutaneous radiation syndrome)
• Chronic health effects:
• Chronic radiation syndrome (CRS)
• Cancer
13. Non-stochastic effects: effects that can be related directly to
the radiation dose received
Stochastic effects: effects that occurs on a random basis
independent of the size of dose.
14. Ionizing radiation and Health
Ionizing radiation can produce tissue damage directly by striking a vital
molecule, such as DNA, or indirectly by striking a water molecule and
producing highly reactive free radicals that chemically attack vital molecules.
The effects of radiation can kill cells, make them unable to reproduce, or
cause nonlethal mutations, producing cancer cells or birth defects in
offspring. The radiosensitivity of normal tissues or cancer cells increases with
their rate of cell division and decreases with their rate of cell specialization.
Highly radiosensitive cells include lymphocytes, bone marrow hematopoietic
cells, germ cells, and intestinal epithelial cells. Radiosensitive cancers include
leukemias and lymphomas, seminoma, dysgerminoma, granulosa cell
carcinoma, adenocarcinoma of the gastric epithelium, and squamous cell
carcinoma of skin, mouth, nose and throat, cervix, and bladder.
15. Harmful effects of radiation include serious disturbances of bone
marrow and other blood-forming organs, burns, and sterility. There
may be permanent damage to genes, which results in genetic
mutations. The mutations can be transmitted to future generations.
Radiation also may produce harmful effects on the embryo or fetus,
bringing about fetal death or malformations. Long-term studies of
groups of persons exposed to radiation have shown that radiation acts
as a carcinogen; that is, it can produce cancer, especially leukemia. It
also may predispose persons to the development of cataracts.
16. Ionizing radiation units
The roentgen (R) is a unit of exposure dose applicable only to x-rays and
gamma rays. It is the amount of radiation that produces 2.58 × 10−4 coulomb
of positive and negative ions passing through 1 kilogram of dry air.
The rad is a unit of absorbed dose equal to 100 ergs of energy absorbed per
1 g of absorbing material; the absorbed dose depends both on the type of
radiation and on the material in which it is absorbed.
The rem is a unit of absorbed dose equivalent that produces the same
biologic effect as 1 rad of high-energy x-rays. For beta and gamma radiation,
1 rem is approximately equal to 1 rad; for alpha radiation, 1 rad is
approximately 20 rem.
17. Only the amount of energy of any type of ionizing radiation that
imparted to (or absorbed by) the human body can cause harm to
health.
To look at biological effects, we must know (estimate) how much
energy is deposited per unit mass of the part (or whole) of our body
with which the radiation is interacting.
19. The international (SI) unit of measure for
absorbed dose
The gray (Gy), which is defined as 1 joule of energy deposited in 1
kilogram of mass. The old unit of measure for this is the rad, which
stands for "radiation absorbed dose." - 1 Gy = 100 rad.
20. Equivalent dose
The biological effect depends not only on the amount of the absorbed
dose but also on the intensity of ionisation in living cells caused by
different type of radiations.
Neutron, proton and alpha radiation can cause 5-20 times more harm
then the same amount of the absorbed dose of beta or gamma
radiation.
The unit of equivalent dose is the sievert (Sv). The old unit of measure
is the rem. - 1 Sv = 100 rem.
21. Coefficients of relative biological effectiveness
- RBE
Gamma and X rays 1
Beta particles 1
Alpha particles 10
Neutrons 5-20
Protons 10
22. Sources of Radiation Exposure
Radiation is permanently present throughout the environment, in the
air, water, food, soil and in all living organisms.
Large proportion of the average annual radiation dose received by
people results from natural environmental sources.
Each member of the world population is exposed, on average, to 2.4
mSv/yr of ionizing radiation from natural sources.
In some areas (in different countries of the world) the natural radiation
dose may be 5 to 10-times higher to large number of people.
24. Effects of radiation dose to the entire body
• 0 – 5 rem received in a short period or over a long period is safe—we
don’t expect observable health effects.
• 5 - 10 rem received in a short period or over a long period is safe—we
don’t expect observable health effects. At this level, an effect is either
nonexistent or too small to observe.
• 10 - 50 rem received in a short period or over a long period—we
don’t expect observable health effects although above 10 rem your
chances of getting cancer are slightly increased. We may also see
short-term blood cell decreases for doses of about 50 rem received in
a matter of minutes.
25. Effects of radiation dose to the entire body
• 50 - 100 rem received in a short period will likely cause some observable
health effects and received over a long period will increase your chances of
getting cancer. Above 50 rem we may see some changes in blood cells, but
the blood system quickly recovers.
• 100 - 200 rem received in a short period will cause nausea and fatigue. 100
- 200 rem received over a long period will increase your chances of getting
cancer.
• 200 - 300 rem received in a short period will cause nausea and vomiting
within 24-48 hours. Medical attention should be sought.
• 300 - 500 rem received in a short period will cause nausea, vomiting, and
diarrhea within hours. Loss of hair and appetite occurs within a week.
Medical attention must be sought for survival; half of the people exposed
to radiation at this level will die if they receive no medical attention.
26. Effects of radiation dose to a smaller area of
the body
• 40 rem or more locally to the eyes can cause cataracts.
• 100 rem - 500 rem or more can cause hair loss for a section of the
body that has hair.
• 200 rem or more locally to the skin can cause skin reddening (similar
to a sunburn).
• 1,000 rem or more can cause a breakdown of the intestinal lining,
leading to internal bleeding, which can lead to illness and death when
the dose is to the abdomen.
• >1,500 rem or more locally to the skin can cause skin reddening and
blistering.
27. We are radioactive
0.012% of our body’s potassium is
radioactive
We expose ourselves to 40 mrem each
year due to the decay of naturally
occurring radioactive isotopes in our
bodies
We are exposed to 5 mrem of radiation
each time we fly roundtrip
If you eat a banana a day for a year you are
exposing yourself to about 3.6 mrem
Smoking a half a pack of cigarettes per day
adds 500 mrem/day
28. Radon
Inert radioactive gas.
Escapes easily from rocks
and soils into the air and
tends to concentrate in
enclosed spaces.
Soil gas infiltration is
recognized as the most
important source of
residential radon.
29. Exposure to Radon
Exposure to radon in the home and workplace is one of the
main risks of ionizing radiation causing tens of thousands of
deaths from lung cancer each year globally
32. Penetrating capacity of different types of
radiation
Ionizing Radiation
Length of run in
air, m
The ionization
density (the
number of ions in
1 μl)
Alpha particles 0,01 6000
Beta particles 10 6
Gamma waves 600 0,1
33. ALARA Principle
“As Low As Reasonably Achievable” means making every
reasonable effort to maintain exposures to ionizing radiation as far
below the dose limits as practical, consistent with the purpose for
which the licensed activity is undertaken, taking into account the
state of technology, the economics of improvements in relation to
state of technology, the economics of improvements in relation to
benefits to the public health and safety, and other societal and
socioeconomic considerations, and in relation to utilization of
nuclear energy and licensed materials in the public interest.
34. Distance
Increasing distance from the radiation source reduces the dose
according to the inverse-square law for a point source. Distance
can sometimes be effectively increased by means as simple as
handling a source with forceps rather than fingers. This could
reduce erythema to the fingers, but the extra few centimeters
distance from the body will give little protection from acute
radiation syndrome
35. Time
The longer that humans are subjected to radiation the larger the
dose will be.
"Quickly putting or dumping wastes outside is not hazardous once
fallout is no longer being deposited. For example, assume the
shelter is in an area of heavy fallout and the dose rate outside is
400 roentgen (R) per hour enough to give a potentially fatal dose in
about an hour to a person exposed in the open. If a person needs
to be exposed for only 10 seconds to dump a bucket, in this 1/360
of an hour he will receive a dose of only about 1 R. Under war
conditions, an additional 1-R dose is of little concern.« (C Kearny)
36. Shielding
Low atomic number materials are recommended to shield beta particles
High atomic number materials are very effective in shielding photons
Shielding is of special importance when time and distance cannot be
completely utilized as safety factors. In such instances lead, which is an
extremely dense material, is used as a protective device. The walls of
diagnostic x-ray rooms are lined with lead, and lead containers are used
for radium, cobalt-60, and other radioactive materials used in
radiotherapy.
Monitoring devices such as the film badge, thermoluminescent
dosimeter, or pocket monitor are worn by persons working near sources
of radiation.
37. Reduction of incorporation into the human
body
Where radioactive contamination is present, a gas mask, dust
mask, or good hygiene practices may offer protection, depending
on the nature of the contaminant. Potassium iodide (KI) tablets
can reduce the risk of cancer in some situations due to slower
uptake of ambient radioiodine. Although this doesn't protect any
organ other than the thyroid gland, their effectiveness is still highly
dependent on the time of ingestion which would protect the gland
for the duration of a twenty-four hour period. They do not prevent
acute radiation syndrome as they provide no shielding from other
environmental radionuclides.
38. Fractionation of dose
If an intentional dose is broken up into a number of smaller doses, with
time allowed for recovery between irradiations, the same total dose
causes less cell death. Even without interruptions, a reduction in dose
rate below 0.1 Gy/h also tends to reduce cell death. This technique is
routinely used in radiotherapy.
The human body contains many types of cells and a human can be
killed by the loss of a single type of cells in a vital organ. For many short
term radiation deaths (3 days to 30 days), the loss of two important
types of cells that are constantly being regenerated causes death. The
loss of cells forming blood cells (bone marrow) and the cells in the
digestive system (microvilli which form part of the wall of the
intestines) is fatal.
39. Reference
• Feynman, Richard; Robert Leighton; Matthew Sands (1963). The Feynman
Lectures on Physics, Vol.1. USA: Addison-Wesley. pp. 2–5.
• European Centre of Technological Safety. "Interaction of Radiation with
Matter" (PDF). Radiation Hazard. Retrieved 5 November 2012.
• Fundamental Quantities and Units for Ionizing Radiation (ICRU Report 85)".
Journal of the ICRU 11 (1). 20
• Prasad KN. Handbook of Radiobiology, 2 nd ed. New York : CRC Press, Inc.;
1995.
• Donnelly EH, Nemhauser JB, Smith JM; et al. (June 2010). "Acute radiation
syndrome: assessment and management". South. Med. J. 103 (6): 541–6.
Editor's Notes
Longer wave length, lower frequency waves (heat and radio) have less energy than shorter wave length, higher frequency waves (X and gamma rays). Not all electromagnetic (EM) radiation is ionizing. Only the high frequency portion of the electromagnetic spectrum which includes X rays and gamma rays is ionizing.
Specific forms of ionizing radiation: Particulate radiation, consisting of atomic or subatomic particles (electrons, protons, etc.) which carry energy in the form of kinetic energy or mass in motion.
Alpha particles and beta particles are considered directly ionizing because they carry a charge and can, therefore, interact directly with atomic electrons through coulombic forces (i.e. like charges repel each other; opposite charges attract each other).
The third type of ionizing radiation includes gamma and X rays, which are electromagnetic, indirectly ionizing radiation. These are indirectly ionizing because they are electrically neutral (as are all electromagnetic radiations) and do not interact with atomic electrons through coulombic forces.
Atoms in their normal state are electrically neutral because the total negative charge of electrons outside the nucleus equals the total positive charge of the nucleus.
These different forms of an element may be stable or unstable (radioactive). However, since they are forms of the same element, they possess identical chemical and biological properties.
The simplest atom is the hydrogen atom. It has one electron orbiting a nucleus on one proton. Any atom which has one proton in the nucleus is a hydrogen atom, like both of the ones shown here. Hydrogen-2 is called deuterium, hydrogen-3 is called tritium. However, while their chemical properties are identical their nuclear properties are quite different as only tritium is radioactive.
Radiation is effective as a cancer treatment because it can kill the cancer cells, however it can also kill or damage nearby cells. When radiation is used to treat cancer it must be pinpointed very carefully. New technologies, similar to imaging techniques used in CT scans, called TomoTherapy help pinpoint radiation treatment. TomoTherapy allows radiologists to apply the ionizing energy directly to the perimeter and within the tumor while avoiding the healthy cells surrounding it. Some aggressive cancers, such as liver cancer, are being treated with a new internal method or radiation therapy. Sent through an artery that feeds the liver, microscopic encapsulated spheres containing radioactive isotopes get directly embedded into the liver and destroy cancer cells. Even though this type of treatment is new, internal radiation treatment is not new. Internal radiation treatment is called brachytherapy.
Exposure to large doses of radiation over a short period of time produces a group of symptoms known as the acute radiation syndrome. acute radiation syndrome is divided into three main presentations: hematopoietic, gastrointestinal and neurological/vascular. These symptoms may or may not be preceded by a prodrome. The speed of onset of symptoms is related to radiation exposure, with greater doses resulting in a shorter delay in symptom onset. These presentations presume whole-body exposure and many of them are markers which are not valid if the entire body has not been exposed. These symptoms include general malaise, nausea, and vomiting, followed by a period of remission of symptoms. Later, the patient develops more severe symptoms such as fever, hemorrhage, fluid loss, anemia, and central nervous system involvement. The symptoms then gradually subside or become more severe, and may lead to death.
Cancer. According to the linear no-threshold model, any exposure to ionizing radiation, even at doses too low to produce any symptoms of radiation sickness, can induce cancer due to cellular and genetic damage. Under the assumption, survivors of acute radiation syndrome face an increased risk developing cancer later in life. The probability of developing cancer is a linear function with respect to the effective radiation dose. In radiation-induced cancer, the speed at which the condition advances, the prognosis, the degree of pain, and every other feature of the disease are not believed to be functions of the radiation dosage.
Non-stochastic effects: effects that can be related directly to the radiation dose received. The effect is more severe with a higher dose. It typically has a threshold, below which the effect will not occur. These are sometimes called deterministic effects. For example, a skin burn from radiation is a non-stochastic effect that worsens as the radiation dose increases.
Stochastic effect: effect that occurs on a random basis independent of the size of dose. The effect typically has no threshold and is based on probabilities, with the chances of seeing the effect increasing with dose. If it occurs, the severity of a stochastic effect is independent of the dose received. Cancer is a stochastic effect.
Three types of units are used to measure ionizing radiation. The roentgen (R) is a unit of exposure dose applicable only to x-rays and gamma rays. It is the amount of radiation that produces 2.58 × 10−4 coulomb of positive and negative ions passing through 1 kilogram of dry air. The rad is a unit of absorbed dose equal to 100 ergs of energy absorbed per 1 g of absorbing material; the absorbed dose depends both on the type of radiation and on the material in which it is absorbed. The rem is a unit of absorbed dose equivalent that produces the same biologic effect as 1 rad of high-energy x-rays. For beta and gamma radiation, 1 rem is approximately equal to 1 rad; for alpha radiation, 1 rad is approximately 20 rem.
Previously, doses administered in radiation therapy were commonly specified as measured exposure doses in roentgens. The current practice is to specify the absorbed dose in the tissue or organ of interest in rads. Many personnel monitoring devices read out in rems. Eventually, the rad and rem may be replaced by the new SI units, the gray and sievert; 1 gray equals 100 rad, and 1 sievert equals 100 rem.Energy emitted from a source is generally referred to as radiation. Examples include heat or light from the sun, microwaves from an oven, X rays from an X-ray tube, and gamma rays from radioactive elements
Radiation has always been a natural part of our environment. There is background radiation all around us. Many radioactive substances exist naturally and are within Earth’s rocks and soil. Most cement, stoneware, and granite contain some radioactive particles, but the levels are not so high. Natural radioactive sources in the soil, water and air contribute to our exposure to ionizing radiation, as well as man-made sources resulting from mining and use of naturally radioactive materials in power generation, nuclear medicine, consumer products, military and industrial applications.
Nuclear power plants utilize Earth’s natural resources. The fuel rods in a nuclear reactor are made of zirconium and pellets of naturally occurring uranium that has been processed by humans so that it contains a higher percentage of the uranium 235 isotope. This isotope occurs naturally and its nuclear decay process emits more energy. These fuel rods are placed in water and the water heats up due to the ionizing energy emitted by the nuclear decay processes that occur in the fuel rods. The heated water creates very hot (550˚F) steam. The steam pushes on a turbine, causing it to turn and as it turns electricity is generated.
Radon is a chemically inert, naturally occurring, radioactive gas. It has no smell, colour, or taste, and is produced from the natural radioactive decay of uranium which is found in rocks and soil.
Radon gas escapes easily from rocks and soils into the air and tends to concentrate in enclosed spaces, such as underground mines, houses, and other buildings.
Soil gas infiltration is recognized as the most important source of residential radon. Other sources of radon include building materials and water extracted from wells, but are of less importance.
Exposure to radon in the home and workplace is one of the main risks of ionizing radiation causing tens of thousands of deaths from lung cancer each year globally. In order to reduce this burden it is important that national authorities have methods and tools based on solid scientific evidence and sound public health policy. The public needs to be aware of radon risks and the means to reduce and prevent these.
Recent findings from case-control studies on lung cancer and exposure to radon in homes completed in many countries allow for substantial improvement in risk estimates and for further consolidation of knowledge by pooling data from these studies. The consistency of the findings from the latest pooled analyses of case-control studies from Europe and North America as well as China provides a strong argument for an international initiative to reduce indoor radon risks.
As Low As Reasonably Achievable; concept utilized in relation to intervention levels following the release of dangerous chemical or nuclear materials.
An approach to radiological control to manage and control exposures (individual and collective) to the work force and to the general public at levels as low as is reasonable, taking into account social, technical, economic, practical and public policy considerations. As used in this Manual, ALARA is not a dose limit but a process that has the objective of attaining doses as far below the applicable controlling limits as is reasonably achievable.
In order to avoid the radiation hazards mentioned above, one must be aware of the three basic principles of time, distance, and shielding involved in protection from radiation. Obviously, the longer one stays near a source of radiation the greater will be the exposure. The same is true of proximity to the source; the closer one gets to a source of radiation the greater the exposure.
Distance
Increasing distance from the radiation source reduces the dose according to the inverse-square law for a point source. Distance can sometimes be effectively increased by means as simple as handling a source with forceps rather than fingers. This could reduce erythema to the fingers, but the extra few centimeters distance from the body will give little protection from acute radiation syndrome.
Time.
The longer that humans are subjected to radiation the larger the dose will be. The advice in the nuclear war manual entitled "Nuclear War survival Skills" published by Cresson Kearny in the USA was that if one needed to leave the shelter then this should be done as rapidly as possible to minimize exposure.
In chapter 12 he states that "Quickly putting or dumping wastes outside is not hazardous once fallout is no longer being deposited. For example, assume the shelter is in an area of heavy fallout and the dose rate outside is 400 roentgen (R) per hour enough to give a potentially fatal dose in about an hour to a person exposed in the open. If a person needs to be exposed for only 10 seconds to dump a bucket, in this 1/360 of an hour he will receive a dose of only about 1 R. Under war conditions, an additional 1-R dose is of little concern."
In peacetime, radiation workers are taught to work as quickly as possible when performing a task which exposes them to radiation. For instance, the recovery of a lost radiography source should be done as quickly as possible.
Shielding
Matter attenuates radiation in most cases, so placing any mass (e.g., lead, dirt, sandbags, vehicles) between humans and the source will reduce the radiation dose. This is not always the case, however; care should be taken when constructing shielding for a specific purpose. For example, although high atomic number materials are very effective in shielding photons, using them to shield beta particles may cause higher radiation exposure due to the production of bremsstrahlung x-rays, and hence low atomic number materials are recommended. Also, using material with a neutron activation cross section to shield neutrons will result in the shielding material itself becoming radioactive and hence more dangerous than if it were not present.
Reduction of incorporation into the human body.
Where radioactive contamination is present, a gas mask, dust mask, or good hygiene practices may offer protection, depending on the nature of the contaminant. Potassium iodide (KI) tablets can reduce the risk of cancer in some situations due to slower uptake of ambient radioiodine. Although this doesn't protect any organ other than the thyroid gland, their effectiveness is still highly dependent on the time of ingestion which would protect the gland for the duration of a twenty-four hour period. They do not prevent acute radiation syndrome as they provide no shielding from other environmental radionuclides.
Fractionation of dose.
If an intentional dose is broken up into a number of smaller doses, with time allowed for recovery between irradiations, the same total dose causes less cell death. Even without interruptions, a reduction in dose rate below 0.1 Gy/h also tends to reduce cell death. This technique is routinely used in radiotherapy.
The human body contains many types of cells and a human can be killed by the loss of a single type of cells in a vital organ. For many short term radiation deaths (3 days to 30 days), the loss of two important types of cells that are constantly being regenerated causes death. The loss of cells forming blood cells (bone marrow) and the cells in the digestive system (microvilli which form part of the wall of the intestines) is fatal.