Laser radiation (LI)

LI is a special type of electromagnetic radiation generated in the wavelength range 0.1 ... 1000 microns.

LI sources are quantum optical generators (COGs) and side factors of some processes (metallurgy, glassmaking).

When working with laser installations, the complex of production factors is mainly dominated by the constant impact on the working of monochromatic laser radiation. Operators can only be exposed to the direct laser beam in the event of a gross violation of safety precautions. However, laser workers may be exposed to reflected and scattered monochromatic radiation. The surfaces reflecting and scattering radiation can be various optical elements located along the beam, targets, devices, as well as walls of industrial premises. Specularly reflecting surfaces are especially dangerous.

Exposure to LI on the eyes results in burns, retinal rupture and permanent loss of vision.

The impact of LI on the skin leads to its nocrosis (necrosis).

Ultraviolet radiation - a kind of radiant energy.

The ultraviolet part of the spectrum includes wavelengths from 0.1 to 0.4 microns. In production conditions, it occurs during electric welding, the action of mercury-quartz lamps, metal melting in electric furnaces, it is used in the film and photographic industries, in photocopying and plasma processes. Ultraviolet radiation is used to prevent vitamin D deficiency in workers in underground mines, as well as in physiotherapy rooms.

Many minerals contain substances that, when illuminated with ultraviolet light, begin to emit visible light. Two minerals - fluorite and zircon - did not differ in X-rays. Both were green. But as soon as the cathode light was connected, the fluorite turned purple, and the zircon turned lemon yellow.

The main artificial sources of ultraviolet radiation are high and medium pressure mercury lamps, xenon arc lamps, and lamps containing mixtures of various gases, which include xenon or mercury vapor.

The biological activity of ultraviolet rays depends on their wavelength.

There are 3 parts of the spectrum with a wavelength:

• 1.0.4-0.31 microns - having a weak biological effect;
• 2. 0.31-0.28 microns - having a strong effect on the skin;
• 3.28-0.20 microns - actively acting on tissue proteins and lipoids that can cause hemolysis.

Biological objects are capable of absorbing the energy of radiation incident on them. In this case, the light photon, interacting with the molecule, knocks the electron out of its orbit. The result is a positively charged molecule, or small ion, that acts as a free radical, disrupting the structure of proteins and damaging cell membranes. Since the photon energy is inversely proportional to the wavelength, short-wave ultraviolet radiation is more damaging to biological objects.

Damage to living objects by ultraviolet radiation is always photochemical, it is not accompanied by a noticeable increase in temperature and can occur after a long latency period.

Small doses of radiation acting for a long time are sufficient for damage.

The effect of ultraviolet radiation on the skin, which exceeds the natural protective capacity of the skin (tanning), leads to burns.

Long-term exposure to ultraviolet radiation contributes to the development of melanoma, different types skin cancer, accelerates aging and the appearance of wrinkles.

Ultraviolet radiation is imperceptible to human eyes, but with intense radiation it typically causes radiation damage (retinal burn). For example, on August 1, 2008, dozens of Russians damaged their retinas during a solar eclipse, despite numerous warnings about the dangers of observing it without eye protection. They complained of a sharp decrease in vision and a spot in front of their eyes.

Intense exposure to ultraviolet radiation can cause occupational dermatitis with diffuse erythema and exudation, damage to the mucous membrane and cornea of ​​the eye (electrophthalmia).

Ionizing radiation (AI)

Ionizing radiation is called the fluxes of particles and electromagnetic quanta formed during nuclear transformations.

The most significant types of ionizing radiation are: short-wave electromagnetic radiation (X-rays and gamma radiation), flows of charged particles: beta particles (electrons and positrons), alpha particles (nuclei of the helium-4 atom), protons, other ions, muons, etc. ., as well as neutrons Most often there are such types of ionizing radiation as X-rays and gamma radiation, fluxes of alpha particles, electrons, neutrons and protons. Ionizing radiation directly or indirectly causes ionization of the medium, i.e. the formation of charged atoms or molecules - ions.

In nature, ionizing radiation is usually generated as a result of spontaneous radioactive decay of radionuclides, nuclear reactions (synthesis and induced fission of nuclei, capture of protons, neutrons, alpha particles, etc.), as well as during the acceleration of charged particles in space (the nature of such acceleration of cosmic particles up to the end is not clear). Artificial sources of ionizing radiation are artificial radionuclides (generate alpha, beta and gamma radiation), nuclear reactors (generate mainly neutron and gamma radiation), radionuclide neutron sources, particle accelerators (generate streams of charged particles, as well as bremsstrahlung photon radiation), X-ray machines (generate bremsstrahlung X-rays)

Alpha radiation is a stream of alpha particles - helium-4 nuclei. Alpha particles from radioactive decay can be easily stopped with a sheet of paper. Beta radiation is the flow of electrons produced by beta decay; to protect against beta particles with energies up to 1 MeV, an aluminum plate several mm thick is sufficient.

X-rays are generated by strong acceleration of charged particles (bremsstrahlung), or by high-energy transitions in the electron shells of atoms or molecules. Both effects are used in X-ray tubes.

X-rays can also be obtained at charged particle accelerators. The so-called synchrotron radiation occurs when a beam of particles is deflected in a magnetic field, as a result of which they experience acceleration in the direction perpendicular to their motion.

On the scale of electromagnetic waves, gamma radiation borders on X-rays, occupying a range of more than high frequencies and energies. In the range of 1-100 keV, gamma radiation and X-ray radiation differ only in source: if a quantum is emitted in a nuclear transition, then it is customary to refer to it as gamma radiation; if during the interactions of electrons or during transitions in the atomic electron shell - to X-ray radiation.

Gamma rays, in contrast to b-rays and c-rays, are not deflected by electric and magnetic fields, are characterized by greater penetrating power at equal energies and other conditions being equal. Gamma quanta cause ionization of the atoms of the substance.

Scopes of gamma radiation:

• · Gamma-ray flaw detection, control of products by transillumination with g-rays.
• Canning food products.
• · Sterilization of medical materials and equipment.
• · Radiation therapy.
• · Level gauges.
• · Gamma-ray logging in geology.
• · Gamma altimeter, measuring the distance to the surface when landing spacecraft.
• Gamma sterilization of spices, grains, fish, meat and other products to increase shelf life

Sources of IR can be natural and artificial radioactive substances, various kinds of nuclear technical installations, medical preparations, numerous control and measuring devices (metal flaw detection, quality control of welded joints). They are also used in agriculture, geological exploration, in the fight against static electricity, etc.

For radiometric studies of borehole sections, it is allowed to use closed radionuclide neutron and gamma sources of ionizing radiation, i.e. gamma-ray logging is carried out - the study of natural gamma radiation of rocks in boreholes to identify radioactive ores, lithological dissection of the section

Specialists - geologists may encounter ionizing radiation during radiometric work, work in mines, mine workings, uranium mines, etc. Radioactive gas radon - 222. The gas emitting alpha particles is constantly formed in rocks. Dangerous when accumulated in mines, basements, on the 1st floor.

Natural sources give a total annual dose of about 200 mrem (space - up to 30 mrem, soil - up to 38 mrem, radioactive elements in human tissues - up to 37 mrem, radon gas - up to 80 mrem and other sources).

Artificial sources add an annual equivalent dose of radiation of about 150-200 mrem (medical devices and research - 100-150 mrem, watching TV -1-3 mrem, coal-fired CHP - up to 6 mrem, test consequences nuclear weapons- up to 3 mrem and other sources).

The World Health Organization (WHO) has established the maximum permissible (safe) equivalent dose of radiation for an inhabitant of the planet at 35 rem, provided it is uniformly accumulated over 70 years of life.

Earlier, people, in order to explain what they do not understand, invented various fantastic things - myths, gods, religion, magical creatures. And although a large number of people still believe in these superstitions, we now know that everything has its own explanation. One of the most interesting, mysterious and surprising topics is radiation. What is it? What types of it exist? What is radiation in physics? How is it absorbed? Is it possible to protect against radiation?

general information

So, the following types of radiation are distinguished: wave motion of the medium, corpuscular and electromagnetic. Most attention will be paid to the latter. Regarding the wave motion of the medium, we can say that it arises as a result of the mechanical motion of a certain object, which causes a consistent rarefaction or compression of the medium. An example is infrasound or ultrasound. Corpuscular radiation is a stream of atomic particles such as electrons, positrons, protons, neutrons, alpha, which is accompanied by natural and artificial decay of nuclei. Let's talk about these two for now.

Influence

Consider solar radiation. It is a powerful healing and preventive factor. The set of accompanying physiological and biochemical reactions that take place with the participation of light are called photobiological processes. They take part in the synthesis of biologically important compounds, serve to obtain information and orientation in space (vision), and can also cause harmful consequences, such as the appearance of harmful mutations, the destruction of vitamins, enzymes, proteins.

About electromagnetic radiation

In the future, the article will be devoted exclusively to him. What does radiation do in physics, how does it affect us? EMP is electromagnetic waves that are emitted by charged molecules, atoms, particles. Antennas or other radiating systems can act as large sources. The radiation wavelength (oscillation frequency) together with the sources is of decisive importance. So, depending on these parameters, gamma, X-ray, optical radiation is emitted. The latter is divided into a number of other subspecies. So, this is infrared, ultraviolet, radio emission, as well as light. The range is up to 10 -13. Gamma radiation is generated by excited atomic nuclei. X-rays can be obtained during deceleration of accelerated electrons, as well as during their transition to non-free levels. Radio waves leave their mark while moving along the conductors of radiating systems (for example, antennas) of alternating electric currents.

About ultraviolet radiation

Biologically, UV rays are the most active. When in contact with the skin, they can cause local changes in tissue and cellular proteins. In addition, the effect on skin receptors is recorded. It affects the whole organism in a reflexive way. Since it is a non-specific stimulator of physiological functions, it has a beneficial effect on immune system organism, as well as on mineral, protein, carbohydrate and fat metabolism. All this manifests itself in the form of a general health-improving, tonic and preventive effect of solar radiation. It should also be mentioned about certain specific properties that a certain wavelength range has. Thus, the effect of radiation on a person with a length of 320 to 400 nanometers contributes to the erythema-tanning effect. In the range from 275 to 320 nm, weak bactericidal and antirachitic effects are recorded. But ultraviolet radiation from 180 to 275 nm damages biological tissue. Therefore, care should be taken. Prolonged direct sunlight, even in a safe spectrum, can lead to severe erythema with swelling of the skin and a significant deterioration in health. Up to an increase in the likelihood of developing skin cancer.

Reaction to sunlight

Infrared radiation should be mentioned first. It has a thermal effect on the body, which depends on the degree of absorption of rays by the skin. The word "burn" is used to characterize its influence. The visible spectrum affects the visual analyzer and the functional state of the central nervous system. And through the central nervous system and on all human systems and organs. It should be noted that we are influenced not only by the degree of illumination, but also by the color spectrum of sunlight, that is, the entire spectrum of radiation. So, the color perception depends on the wavelength and influences our emotional activity, as well as the functioning of various body systems.

Red stimulates the psyche, intensifies emotions and gives a feeling of warmth. But it quickly tires, promotes muscle tension, increased breathing and increased blood pressure. Orange evokes feelings of well-being and fun, while yellow is uplifting and stimulating. nervous system and vision. Green calms, is useful during insomnia, when overworked, increases the overall tone of the body. Purple has a relaxing effect on the psyche. Blue calms the nervous system and maintains muscle tone.

Small digression

Why, considering what radiation is in physics, are we talking more about EMP? The fact is that it is in most cases that it is meant when they refer to the topic. The same corpuscular radiation and wave motion of the medium is an order of magnitude less scaled and known. Very often, when they talk about the types of radiation, they mean only those into which the EMP is divided, which is fundamentally wrong. After all, speaking about what radiation is in physics, attention should be paid to all aspects. But at the same time, emphasis is placed on the most important points.

About radiation sources

We continue to consider electromagnetic radiation. We know that it represents waves that arise when an electrical or magnetic field... This process is interpreted by modern physics from the point of view of the theory of particle-wave dualism. This is how it is recognized that the minimum portion of EMP is a quantum. But at the same time, it is believed that it also has frequency-wave properties on which the main characteristics depend. To improve the possibilities of classification of sources, different emission spectra of EMP frequencies are distinguished. So this:

1. Hard radiation (ionized);
2. Optical (visible to the eye);
3. Thermal (it is infrared);
4. Radio frequency.

Some of them have already been considered. Each radiation spectrum has its own unique characteristics.

The nature of the sources

Depending on their origin, electromagnetic waves can occur in two cases:

1. When there is a disturbance of artificial origin.
2. Registration of radiation coming from a natural source.

What about the former? Artificial sources are most often a side effect that arises from the operation of various electrical devices and mechanisms. Radiation of natural origin generates the Earth's magnetic field, electrical processes in the planet's atmosphere, nuclear fusion in the bowels of the sun. The degree of strength of the electromagnetic field depends on the power level of the source. Conventionally, the radiation that is registered is divided into low-level and high-level. The first ones are:

1. Almost all devices are equipped with a CRT display (like, for example, a computer).
2. Various Appliances, ranging from climate systems and ending with irons;
3. Engineering systems that provide the supply of electricity to various objects. An example is the power cable, sockets, electricity meters.

High-level electromagnetic radiation is possessed by:

1. Power lines.
2. All electric transport and its infrastructure.
3. Radio and TV towers, as well as mobile and mobile communication stations.
4. Elevators and other lifting equipment where electromechanical power plants are used.
5. Devices for converting voltage in the network (waves emanating from a distribution substation or transformer).

Separately, special equipment is allocated that is used in medicine and emits hard radiation. Examples include MRI, X-ray machines, and the like.

Influence of electromagnetic radiation on humans

In the course of numerous studies, scientists have come to the sad conclusion that the long-term influence of EMR contributes to a real explosion of diseases. Moreover, many violations occur at the genetic level. Therefore, protection against electromagnetic radiation is relevant. This is due to the fact that EMP has high level biological activity. In this case, the result of the influence depends on:

1. The nature of the radiation.
2. The duration and intensity of the influence.

Specific moments of influence

It all depends on the localization. Radiation absorption can be local or general. As an example of the second case, we can cite the effect that power lines have. Local effects include the electromagnetic waves emitted by electronic watches or mobile phone... The thermal effects should also be mentioned. Due to the vibration of the molecules, the field energy is converted into heat. Microwave emitters work according to this principle, which are used to heat various substances. It should be noted that when influencing a person, the thermal effect is always negative, and even detrimental. It should be noted that we are constantly exposed to radiation. In production, at home, moving around the city. Over time, the negative effect only intensifies. Therefore, protection against electromagnetic radiation is becoming increasingly important.

How can you protect yourself?

Initially, you need to know what you have to deal with. A special device for measuring radiation will help with this. It will allow you to assess the security situation. In production, absorbent screens are used for protection. But, alas, they are not designed for use at home. As a starting point, you can follow three guidelines:

1. Stay at a safe distance from devices. For power lines, television and radio towers, this is at least 25 meters. With CRT monitors and TVs, thirty centimeters are enough. Electronic watches should be no closer than 5 cm. It is not recommended to bring radio and cell phones closer than 2.5 centimeters. You can find a place using a special device - a fluxmeter. The admissible dose of radiation fixed by it should not exceed 0.2 μT.
2. Try to reduce the time when you have to be irradiated.
3. Always switch off unused electrical appliances. After all, even being inactive, they continue to emit EMP.

About the silent killer

And we will conclude the article with an important, albeit rather poorly known, topic in wide circles - radiation. Throughout his life, development and existence, a person was exposed to the natural background. Natural radiation radiation can be conditionally divided into external and internal radiation. The first includes cosmic radiation, solar radiation, the influence of the earth's crust and air. Even the building materials from which houses and structures are made generate a certain background.

Radiation radiation has a significant penetrating power, so it is problematic to stop it. So, in order to completely isolate the rays, you need to hide behind a wall of lead, 80 centimeters thick. Internal exposure occurs when natural radioactive substances enter the body along with food, air, and water. In the bowels of the earth, you can find radon, thoron, uranium, thorium, rubidium, radium. All of them are absorbed by plants, can be in water - and when they are consumed, they enter our body.

The computer is one of the most remarkable achievements of human intelligence. The possibility of direct dialogue between users through computers and huge PC resources has led to the fact that millions of people spend more and more time in front of his screen. Over time, computer users develop a set of specific complaints about their well-being.

This makes us think about the effect of radiation from a computer on human health. There are many reasons for this. A number of scientists associate health problems with the exposure of people to electromagnetic radiation from household microwave sources.

What is the harm of computer radiation

We are the first generation of humans to live in an ocean of vast amounts of visible and invisible radiation. Therefore, there is still no reliable statistics that summarizes all the studies of scientists on this topic. So what do the pundits say?

Every PC is a source of low frequency and radio frequency radiation. Health experts say:

• both types of rays are carcinogenic;
• they increase the risk of cardiovascular disease and hormonal disorders;
• as well as Alzheimer's disease, asthma and depression.

All parts of the computer can be harmful. The processor generates this very microwave radiation, which "with pleasure" spreads in space in the form of electromagnetic waves, often carrying misinformation to the human electromagnetic field.

To determine in which direction the harmful radiation is greatest from the monitor, remember that the front of the monitor has a protective cover. But the back wall and side surfaces are not protected. Manufacturers of computer equipment considered ensuring the safety of the operator sitting in front of the screen as a paramount task, therefore the opinion that the radiation from the monitor from behind and from the sides is stronger is quite reasonable.

Monitors with a cathode-ray tube, thank God, are becoming rarities of history. The harm from them was very significant. The LCD monitors that replaced them are certainly safer, but they still emit radiation. By the way, the word radiation, indicated in the computer documentation, is translated as radiation, but not as radioactivity.

Due to the heating of the motherboard and case, air is deionized and harmful substances are released into the environment. This is why the air in rooms with computers constantly running is very hard to breathe. For people with a weak respiratory system, such a factor can have a detrimental effect, provoking asthma. It is further aggravated by the influence of the electrostatic field of a computer and a monitor on dust particles suspended in the air. Electrified, they form a "dusty cocktail" that makes breathing difficult.

The presence of a touch screen does not at all guarantee you the absence of radiation. After all, your fingers, performing manipulations on the screen, touch it all the time, and a few millimeters from the wi-fi antenna.

Special attention should be paid to the problem of radiation from laptops, which were conceived as portable devices for working on the road. The use of these convenient and multifunctional devices during a full working day may well cause all kinds of pathologies and diseases. After all, he, like an ordinary computer, is a source of electromagnetic radiation, and even located in the immediate vicinity of a person. Many users even inadvertently place it on their knees, in close proximity to vital organs.

Computer radiation and pregnancy

Pregnancy is an extremely important time in a woman's life. From the moment of conception until the birth of the child, the growing fetus is extremely sensitive to adverse external influences... Therefore, intrauterine damage to the embryo electromagnetic field can occur at any stage of its development. Especially dangerous in this regard early dates pregnancy, when miscarriages most often occur and malformations of an unborn baby develop. Therefore, the expectant mother should be very responsible about the influence of computer radiation on pregnancy.

Despite the compactness of a laptop, radiation from it during pregnancy is no less dangerous than the same effect from a regular computer - the intensity is the same, plus the effect of the Wi-Fi transmitter. In addition, many women, even during pregnancy, do not part with the habit of keeping it portable device on your knees, that is, in the immediate vicinity of the developing baby.

Ways to protect against harmful effects of your computer

The flip side of technical progress is the dangers associated with it. How can they be avoided or at least minimized? How can I reduce radiation from a computer? Information about its harmful effects should logically be accompanied by recommendations on how to protect against its radiation.

Do Plants Help Protect Against Computer Radiation

Even among reputable office workers, there is a perception that some plants protect against computer radiation.

So which flower protects against computer radiation? Cactus is traditionally preferred here. Under this myth even summed up a "scientific basis": the needles of the plant are attributed to the role of antennas, formulas are given and calculations are made. If there was a grain of truth in this statement, then in the homeland of cacti - Mexico, there should be problems with the operation of radars, but they are not.

The reality is that neither a cactus nor any other plant will protect against computer radiation!

A flower near a computer can cheer you up, decorate a strict work atmosphere, and become a positive emotional component in everyday work. And the "emotional placebo" is able to neutralize the harmful effects of electromagnetic radiation.

Concluding all of the above, we conclude that protection against microwave radiation from a computer begins from the moment you choose this companion for your family in the store. And it ends with a reasonable approach to its operation and dosed time in front of an invitingly flickering screen.

Radioactive (or ionizing) radiation is energy that is released by atoms in the form of particles or waves of an electromagnetic nature. A person is exposed to such an impact both through natural and through anthropogenic sources.

The beneficial properties of radiation made it possible to successfully use it in industry, medicine, scientific experiments and research, agriculture and other fields. However, with the spread of the use of this phenomenon, a threat to human health has arisen. A small dose of radioactive radiation can increase the risk of acquiring serious diseases.

The difference between radiation and radioactivity

Radiation, in a broad sense, means radiation, that is, the propagation of energy in the form of waves or particles. Radioactive radiation is divided into three types:

• alpha radiation - flux of helium-4 nuclei;
• beta radiation - electron flow;
• gamma radiation is a stream of high-energy photons.

The characterization of radioactive emissions is based on their energy, transmission properties and the type of emitted particles.

Alpha radiation, which is a flux of positively charged particles, can be trapped by air or clothing. This species practically does not penetrate the skin, but when it enters the body, for example, through cuts, it is very dangerous and has a detrimental effect on internal organs.

Beta radiation has more energy - electrons move at high speed, and their size is small. That's why given view radiation penetrates through thin clothing and skin deep into tissues. Beta radiation can be shielded with a few millimeters of aluminum or a thick wooden board.

Gamma radiation is a high-energy radiation of an electromagnetic nature that has a strong penetrating power. To protect against it, you need to use a thick layer of concrete or a plate of heavy metals such as platinum and lead.

The phenomenon of radioactivity was discovered in 1896. The discovery was made by the French physicist Becquerel. Radioactivity is the ability of objects, compounds, elements to emit ionizing study, that is, radiation. The reason for the phenomenon is instability atomic nucleus, which releases energy upon decay. There are three types of radioactivity:

• natural - typical for heavy elements, the ordinal number of which is more than 82;
• artificial - initiated specifically by nuclear reactions;
• directed - characteristic of objects that themselves become a source of radiation if they are strongly irradiated.

Elements with radioactivity are called radionuclides. Each of them is characterized by:

• half-life;
• the type of radiation emitted;
• radiation energy;
• and other properties.

Sources of radiation

The human body is regularly exposed to radioactive radiation. Cosmic rays account for approximately 80% of the amount received annually. Air, water and soil contain 60 radioactive elements that are sources of natural radiation. The main natural source of radiation is considered to be the inert gas radon, which is released from the ground and rocks. Radionuclides also enter the human body with food. Some of the ionizing radiation that humans are exposed to comes from anthropogenic sources, ranging from nuclear power generators and nuclear reactors to radiation used for treatment and diagnosis. Today, common artificial radiation sources are:

• medical equipment (the main anthropogenic source of radiation);
• radiochemical industry (mining, enrichment of nuclear fuel, processing of nuclear waste and their recovery);
• radionuclides used in agriculture, light industry;
• accidents at radiochemical plants, nuclear explosions, radiation releases
• Construction Materials.

Radiation exposure, according to the method of penetration into the body, is divided into two types: internal and external. The latter is typical for radionuclides (aerosol, dust) sprayed into the air. They come into contact with skin or clothing. In this case, the sources of radiation can be removed by rinsing them off. External radiation causes burns to the mucous membranes and skin. At internal type the radionuclide enters the bloodstream, for example, by injection into a vein or through wounds, and is removed by excretion or therapy. Such radiation provokes malignant tumors.

The radioactive background significantly depends on geographic location- in some regions, the radiation level can be hundreds of times higher than the average.

The effect of radiation on human health

Due to its ionizing effect, radioactive radiation leads to the formation of free radicals in the human body - chemically active aggressive molecules that cause damage to cells and their death.

Cells of the gastrointestinal tract, reproductive and hematopoietic systems are especially sensitive to them. Radioactive irradiation disrupts their work and causes nausea, vomiting, stool disturbances, and fever. By acting on the tissues of the eye, it can lead to radiation cataract. The consequences of ionizing radiation also include damage such as vascular sclerosis, impairment of immunity, and a violation of the genetic apparatus.

The system of transmission of hereditary data has a fine organization. Free radicals and their derivatives are capable of disrupting the structure of DNA - the carrier of genetic information. This leads to the emergence of mutations that affect the health of subsequent generations.

The nature of the effect of radioactive radiation on the body is determined by a number of factors:

• type of radiation;
• radiation intensity;
• individual characteristics of the organism.

The results of radiation exposure may not appear immediately. Sometimes its consequences become noticeable after a considerable period of time. Moreover, a large single dose of radiation is more dangerous than long-term exposure to low doses.

The absorbed amount of radiation is characterized by a quantity called Sievert (Sv).

• The normal background radiation does not exceed 0.2 mSv / h, which corresponds to 20 microroentgens per hour. When a tooth is X-rayed, a person receives 0.1 mSv.

• The lethal single dose is 6-7 Sv.

Application of ionizing radiation

Radioactive radiation is widely used in technology, medicine, science, military and nuclear industries and other spheres of human activity. The phenomenon underlies such devices as smoke detectors, power generators, icing alarms, and air ionizers.

In medicine, radioactive radiation is used in radiation therapy to treat cancer. Ionizing radiation has made it possible to create radiopharmaceuticals. With their help, diagnostic examinations are carried out. On the basis of ionizing radiation, devices are arranged for the analysis of the composition of compounds, sterilization.

The discovery of radioactive radiation was without exaggeration revolutionary - the use of this phenomenon brought humanity to a new level of development. However, this also caused a threat to the environment and human health. In this regard, maintaining radiation safety is an important task of our time.

"The attitude of people to a particular danger is determined by how well they are familiar with it."

This material is a generalized answer to numerous questions arising from users of devices for detecting and measuring radiation in a domestic environment.
The minimal use of specific terminology of nuclear physics when presenting the material will help you to freely navigate this environmental issue without succumbing to radiophobia, but also without undue complacency.

The danger of RADIATION, real and perceived

"One of the first discovered natural radioactive elements was named" radium "
- translated from Latin - emitting rays, emitting ".

Each person in the environment is trapped by various phenomena that influence him. These include heat, cold, magnetic and normal storms, torrential rains, heavy snowfalls, strong winds, sounds, explosions, etc.

Thanks to the presence of the senses allocated to him by nature, he can quickly respond to these phenomena with the help of, for example, a canopy from the sun, clothing, housing, medicines, screens, shelters, etc.

However, in nature there is a phenomenon to which a person, due to the lack of the necessary sense organs, cannot instantly react - this is radioactivity. Radioactivity is not a new phenomenon; radioactivity and accompanying radiation (so-called ionizing) have always existed in the Universe. Radioactive materials are part of the Earth and even a person is slightly radioactive, because any living tissue contains the smallest quantities of radioactive substances.

The most unpleasant property of radioactive (ionizing) radiation is its effect on the tissues of a living organism, therefore, appropriate measuring instruments are needed that would provide operational information for making useful decisions before a long time passes and undesirable or even disastrous consequences appear. will begin to feel not immediately, but only after some time. Therefore, information on the presence of radiation and its power must be obtained as early as possible.
Enough of the riddles, however. Let's talk about what radiation and ionizing (i.e. radioactive) radiation are.

Ionizing radiation

Any medium consists of the smallest neutral particles - atoms, which are composed of positively charged nuclei and surrounding negatively charged electrons. Every atom is like solar system in miniature: “planets” move in orbits around a tiny nucleus - electrons.
Atom nucleus consists of several elementary particles, protons and neutrons, confined by nuclear forces.

Protons particles with a positive charge equal in absolute value to the charge of electrons.

Neutrons neutral, non-charged particles. The number of electrons in an atom is exactly the same as the number of protons in the nucleus, so each atom is generally neutral. The mass of a proton is almost 2000 times the mass of an electron.

The number of neutral particles (neutrons) present in the nucleus can be different for the same number of protons. Such atoms having nuclei with the same number protons, but differing in the number of neutrons, belong to varieties of the same chemical element, called "isotopes" of this element. To distinguish them from each other, a number is assigned to the symbol of the element, equal to the sum of all particles in the nucleus of a given isotope. So uranium-238 contains 92 protons and 146 neutrons; uranium 235 also has 92 protons, but 143 neutrons. All isotopes of a chemical element form a group of "nuclides". Some nuclides are stable, i.e. do not undergo any transformations, while others emitting particles are unstable and transform into other nuclides. As an example, let's take an atom of uranium - 238. From time to time, a compact group of four particles escapes from it: two protons and two neutrons - an "alpha particle (alpha)". Uranium-238 is thus transformed into an element, the nucleus of which contains 90 protons and 144 neutrons - thorium-234. But thorium-234 is also unstable: one of its neutrons turns into a proton, and thorium-234 turns into an element with 91 protons and 143 neutrons in its nucleus. This transformation also affects the electrons (beta) moving in their orbits: one of them becomes, as it were, superfluous, without a pair (proton), so it leaves the atom. A chain of numerous transformations, accompanied by alpha or beta radiation, ends with a stable lead nuclide. Of course, there are many similar chains of spontaneous transformations (decays) of different nuclides. The half-life is a period of time during which the initial number of radioactive nuclei, on average, is halved.
With each act of decay, energy is released, which is transmitted in the form of radiation. Often an unstable nuclide turns out to be in an excited state, and the emission of a particle does not lead to a complete removal of the excitation; then he throws out a portion of energy in the form of gamma radiation (gamma quantum). As in the case of X-rays (which differ from gamma rays only in frequency), there is no emission of any particles. The whole process of spontaneous decay of an unstable nuclide is called radioactive decay, and the nuclide itself is a radionuclide.

Different types of radiation are accompanied by the release of different amounts of energy and have different penetrating power; therefore, they have a different effect on the tissues of a living organism. Alpha radiation is trapped, for example, by a sheet of paper and is practically unable to penetrate the outer layer of the skin. Therefore, it does not pose a danger as long as the radioactive substances emitting alpha particles do not enter the body through an open wound, with food, water or inhaled air or steam, for example, in a bath; then they become extremely dangerous. Beta - a particle has a greater penetrating ability: it penetrates into the tissues of the body to a depth of one or two centimeters or more, depending on the amount of energy. The penetrating power of gamma rays, which travels at the speed of light, is very high: only a thick lead or concrete slab can stop it. Ionizing radiation is characterized by a number of measurable physical quantities. These include energy quantities. At first glance, it may seem that they are enough for recording and assessing the impact of ionizing radiation on living organisms and humans. However, these energetic values ​​do not reflect the physiological effects of ionizing radiation on the human body and other living tissues, are subjective, and are different for different people. Therefore, averaged values ​​are used.

Sources of radiation are natural, present in nature, and not dependent on humans.

It has been established that of all natural sources of radiation, the greatest danger is represented by radon, a heavy gas without taste, smell, and at the same time invisible; with their daughter products.

Radon is released from the earth's crust everywhere, but its concentration in the outside air differs significantly at different points in the world. Paradoxical as it may seem at first glance, a person receives the main radiation from radon while in a closed, unventilated room. Radon concentrates in indoor air only when they are sufficiently isolated from the external environment. Escaping through the foundation and the floor from the ground or, less often, being released from building materials, radon accumulates in the room. Sealing the premises for the purpose of insulation only aggravates the matter, since it makes it even more difficult for the radioactive gas to escape from the room. The radon problem is especially important for low-rise buildings with careful sealing of the premises (in order to preserve heat) and the use of alumina as an additive to building materials(the so-called "Swedish problem"). The most common building materials - wood, brick and concrete - emit relatively little radon. Granite, pumice, alumina products, and phosphogypsum have much higher specific radioactivity.

Another, usually less important, source of radon entering the premises is water and natural gas used for cooking and heating homes.

The concentration of radon in commonly used water is extremely low, but water from deep wells or artesian wells contains a lot of radon. However, the main danger does not come from drinking water, even with a high content of radon in it. Usually, people consume most of the water in food and in the form of hot drinks, and when boiling water or preparing hot dishes, radon almost completely evaporates. A much greater danger is the ingress of water vapor with a high content of radon into the lungs along with the inhaled air, which most often occurs in a bathroom or steam room (steam room).

Radon penetrates into natural gas underground. As a result of preliminary processing and during the storage of gas before it enters the consumer, most of the radon evaporates, but the concentration of radon in the room can increase noticeably if stoves and other heating gas appliances are not equipped with an exhaust hood. In the presence of supply and exhaust ventilation, which communicates with the outside air, the concentration of radon in these cases does not occur. This also applies to the house as a whole - focusing on the readings of radon detectors, you can set the ventilation mode of the premises, which completely eliminates the threat to health. However, given that the release of radon from the soil is seasonal, it is necessary to monitor the ventilation efficiency three to four times a year, not allowing radon concentration to be exceeded.

Other sources of radiation, unfortunately potentially dangerous, were created by man himself. Sources of artificial radiation are artificial radionuclides, beams of neutrons and charged particles created using nuclear reactors and accelerators. They are called technogenic sources of ionizing radiation. It turned out that along with a dangerous character for humans, radiation can be put at the service of humans. Here is a far from complete list of fields of application of radiation: medicine, industry, Agriculture, chemistry, science, etc. A calming factor is the controlled nature of all activities associated with the receipt and use of artificial radiation.

Tests of nuclear weapons in the atmosphere, accidents at nuclear power plants and nuclear reactors and the results of their work, which are manifested in radioactive fallout and radioactive waste, stand apart in terms of their impact on humans. However, only emergencies, such as the Chernobyl accident, can have an uncontrolled impact on humans.
The rest of the work is easily supervised at a professional level.

When radioactive fallout occurs in some areas of the Earth, radiation can enter the human body directly through agricultural products and food. It is very simple to protect yourself and your loved ones from this danger. When buying milk, vegetables, fruits, herbs, and any other products, it will not be superfluous to turn on the dosimeter and bring it to the purchased product. No radiation is visible - but the device will instantly detect the presence of radioactive contamination. This is our life in the third millennium - the dosimeter is becoming an attribute of everyday life, like a handkerchief, a toothbrush, or soap.

EFFECTS OF IONIZING RADIATION ON BODY TISSUES

The damage caused in a living organism by ionizing radiation will be the greater, the more energy it transfers to the tissues; the amount of this energy is called a dose, by analogy with any substance entering the body and fully assimilated by it. The body can receive a dose of radiation regardless of whether the radionuclide is outside the body or inside it.

The amount of radiation energy absorbed by the irradiated tissues of the body, calculated per unit mass, is called the absorbed dose and is measured in Grays. But this value does not take into account the fact that with the same absorbed dose, alpha radiation is much more dangerous (twenty times) than beta or gamma radiation. The dose thus recalculated is called the equivalent dose; it is measured in units called Sieverts.

It should also be borne in mind that some parts of the body are more sensitive than others: for example, at the same equivalent dose of radiation, the occurrence of cancer in the lungs is more likely than in the thyroid gland, and irradiation of the gonads is especially dangerous due to the risk of genetic damage. Therefore, human radiation doses should be taken into account with different coefficients. Multiplying the equivalent doses by the appropriate coefficients and summing up over all organs and tissues, we obtain the effective equivalent dose, which reflects the total effect of radiation on the body; it is also measured in Sievert.

Charged particles.

Alpha and beta particles penetrating into the tissues of the body lose energy due to electrical interactions with the electrons of those atoms near which they pass. (Gamma rays and X-rays transfer their energy to matter in several ways, which ultimately also lead to electrical interactions.)

Electrical interactions.

In a time of the order of ten trillionth of a second after the penetrating radiation reaches the corresponding atom in the tissue of the body, an electron is detached from this atom. The latter is negatively charged, so the rest of the initially neutral atom becomes positively charged. This process is called ionization. The detached electron can further ionize other atoms.

Physicochemical changes.

Both a free electron and an ionized atom usually cannot remain in this state for a long time and for the next ten billionths of a second participate in a complex chain of reactions, as a result of which new molecules are formed, including such extremely reactive ones as "free radicals".

Chemical changes.

Over the next millionths of a second, the formed free radicals react both with each other and with other molecules and, through a chain of reactions not yet fully understood, can cause chemical modification of biologically important molecules necessary for the normal functioning of the cell.

Biological effects.

Biochemical changes can occur both in a few seconds and in decades after irradiation and cause immediate cell death or changes in them.

For information, and not for intimidation, especially people who have decided to devote themselves to working with ionizing radiation, you should know the maximum permissible doses. The units of measurement of radioactivity are given in Table 1. According to the conclusion of the International Commission on Radiation Protection for 1990, harmful effects can occur at equivalent doses of at least 1.5 Sv (150 rem) received during the year, and in cases of short-term exposure at doses higher 0.5 Sv (50 rem). When the radiation exposure exceeds a certain threshold, radiation sickness occurs. Distinguish between chronic and acute (with a single massive exposure) forms of this disease. In terms of severity, acute radiation sickness is divided into four degrees, ranging from a dose of 1-2 Sv (100-200 rem, 1st degree) to a dose of more than 6 Sv (600 rem, 4th degree). The fourth degree can be fatal.

Doses received under normal conditions are negligible compared to those indicated. The equivalent dose rate created by natural radiation ranges from 0.05 to 0.2 μSv / h, i.e. from 0.44 to 1.75 mSv / year (44-175 mrem / year).
For medical diagnostic procedures - X-rays, etc. - a person receives approximately 1.4 mSv / year.

Since small doses of radioactive elements are present in brick and concrete, the dose increases by another 1.5 mSv / year. Finally, due to emissions from modern coal-fired thermal power plants and when flying in an airplane, a person receives up to 4 mSv / year. In total, the existing background can reach 10 mSv / year, but on average does not exceed 5 mSv / year (0.5 rem / year).

Such doses are completely harmless to humans. The dose limit in addition to the existing background for a limited part of the population in areas of high radiation is 5 mSv / year (0.5 rem / year), i.e. with a 300-fold margin. For personnel working with sources of ionizing radiation, the maximum permissible dose is 50 mSv / year (5 rem / year), i.e. 28 μSv / h at a 36-hour work week.

According to hygienic standards NRB-96 (1996) acceptable levels dose rate for external irradiation of the whole body from man-made sources for the premises of permanent residence of personnel - 10 μGy / h, for residential premises and territories where persons from the population are constantly located - 0.1 μGy / h (0.1 μSv / h, 10 μR / h).

HOW TO MEASURE RADIATION

A few words about registration and dosimetry of ionizing radiation. There are various methods of registration and dosimetry: ionization (associated with the passage of ionizing radiation in gases), semiconductor (in which the gas is replaced solid body), scintillation, luminescent, photographic. These methods are the basis of the work. dosimeters radiation. Among the gas-filled ionizing radiation sensors, one can note ionization chambers, fission chambers, proportional counters and Geiger-Muller counters... The latter are relatively simple, the cheapest, not critical to the operating conditions, which led to their widespread use in professional dosimetry equipment designed to detect and evaluate beta and gamma radiation. When a Geiger-Müller counter is used as a sensor, any ionizing particle entering the sensitive volume of the counter causes a self-discharge. Precisely falling into the sensitive volume! Therefore, alpha particles are not registered, because they cannot get there. Even when registering beta particles, it is necessary to bring the detector closer to the object to make sure that there is no radiation, because in the air, the energy of these particles can be weakened, they may not pass through the device housing, they will not fall into the sensitive element and will not be detected.

Doctor of Physical and Mathematical Sciences, Professor MEPhI N.M. Gavrilov
the article was written for the company "Kvarta-Rad"