Radon- the heaviest of the noble gases, which earlier, even 20–30 years ago, were more often called inert gases. It has no smell or taste, is transparent and colorless. Its density at 0°C is 9.81 kg/m3, i.e. almost 8 times the density of air. Radon is the rarest and heaviest radioactive gas; it has amazing properties: at a temperature of minus 62 C, it turns into a colorless liquid that is seven times heavier than water and which fluoresces with a bright blue or violet color. Around minus 71 C°, radon becomes a solid and opaque substance, emitting a blue glow. Without heating, radon emits heat and over time can form: solid radioactive elements.
Radon is 110 times heavier than hydrogen, 55 times heavier than helium and 7.5 times heavier than air. One liter of gas weighs about 9.9 grams. However, this information has not yet been verified, since to obtain one liter of radon from radium salts, you need about 500 kg of radium. Yes, even if such a volume of gas were obtained in any way, then, according to Professor Rutherford, the scientist who discovered radon in 1900, no vessel could hold it, since the amount of heat emitted by radon would melt the vessel, in which concluded it. (P.R. Taube, E.I. Rudenko, “From hydrogen to Nobelium?”). Radon is chemically inert and reacts only with strong fluorinating agents. All isotopes of radon are radioactive and decay quite quickly: the most stable isotope 222 Rn has a half-life of 3.8 days, the second most stable isotope 220 Rn (thoron) - 55.6 s.
Why does radon, having only short-lived isotopes, not completely disappear from the atmospheric air? It turns out that it constantly enters the atmosphere from terrestrial rocks: 222 Rn - during the fission of 238 U nuclei, and 220 Rn - during the fission of 232 Th nuclei. There are quite a lot of rocks containing uranium and thorium in the earth's crust (for example, granites, phosphorites), so the loss is compensated by the supply and there is a certain equilibrium concentration of radon in the atmosphere. It would seem that the role of this extremely rare, inert, unstable chemical element in our lives cannot only be significant, but even simply noticeable. However, this is not at all true. More precisely, about 20 years ago they began to believe that this might not be the case.
The 222Rn isotope provides approximately 50–55% of the radiation dose that every inhabitant of the Earth receives annually, the 220Rn isotope adds another ~5–10% to this. However, studies have shown that in some areas radon exposure can be many times and even several orders of magnitude higher than average values.
(Alfa) - radioactivity (alpha radiation) - is a stream of alpha particles emitted during the radioactive decay of elements heavier than lead or formed during nuclear reactions. An alpha particle is actually a helium nucleus consisting of two protons and two neutrons. It has a static electric charge of +2, its mass number is 4. Alpha radiation has low penetrating power (only a few centimeters in the air and tens of microns in biological tissue). The flow of alpha particles can easily be stopped even by a sheet of paper. Therefore, even the highest-energy alpha particles cannot penetrate the rough upper layers of skin cells. However, alpha radiation is much more dangerous when the source of the alpha particles is inside the body. Below are the main alpha emitters and the corresponding effective doses that a person can receive in a year of drinking water containing any of these alpha radionuclides with a radioactivity level of 0.1 Bq/l.
GEOLOGY OF RADON
The formation and distribution of radon is studied by geology, since rocks are its primary source. First of all, the content of radon in the environment depends on the concentration of parent elements in rocks and soils. Therefore, a geological map can give the first idea of the distribution of radon in the environment.
Despite the fact that radioactive elements are found everywhere in varying quantities, their distribution in the earth's crust is very uneven. The highest concentrations of uranium are characteristic of igneous (igneous) rocks, especially nitite. High concentrations of uranium can also be associated with dark shales, sedimentary rocks containing phosphates, and metamorphic rocks formed from these sediments. Naturally, both soils and clastic deposits formed as a result of the processing of the above-mentioned rocks will also be enriched in uranium.
In addition, the main sources containing radon are rocks and sedimentary rocks containing uranium (radium):
- bauxites and carbonaceous shales of the Tula horizon of the Lower Carboniferous, occurring at depths from 0 to 50 m and with uranium contents of more than 0.002%;
- Carbonaceous-clayey dictyonema shales, glauconite and obol sands and sandstones of the Pakerort, ceratopygian and Latorinian horizons of the Lower Ordovician, occurring at depths from 0 to 50 m with a uranium content of more than 0.005%.
- carbon-containing gravelites, sandstones and siltstones of the Gdov Vendian horizon, occurring at depths from 0 to 100 m with a uranium content of more than 0.005%;
- rapakivi granites of the Upper Proterozoic, occurring near the surface and having a uranium content of more than 0.0035%;
- potassic, microcline and plagiomicrocline granites of Proterozoic-Archean age with a uranium content of more than 0.005%;
- granitized and migmatized Archean gneisses occurring near the surface, in which uranium is more than 3.5 g/t.
As a result of radioactive decay, radon atoms enter the crystal lattice of minerals. The process of radon release from minerals and rocks into a vapor or crack space is called emanation. Not all radon atoms can be released into the pore space, so the emanation coefficient is used to characterize the degree of radon release. Its value depends on the nature of the rock, its structure and the degree of its fragmentation. The smaller the rock grains, the larger the outer surface of the grains, the more active the emanation process.
The further fate of radon is related to the nature of the filling of the pore space of the rock. In the aeration zone, that is, above the groundwater level, the pores and cracks of rocks and soils are filled, as a rule, with air. Below the groundwater level, the entire void space of the rocks is filled with water (in oil and gas bearing areas it can also be filled with oil and gas). In the first case, radon, like any gas, spreads according to the laws of diffusion. In the second, it can also migrate with water. The migration distance of radon is determined by its half-life. Since this period is not very long, the migration distance of radon cannot be large. For dry rock it is greater, however, as a rule, radon migrates in an aquatic environment. That is why the study of the behavior of radon in water is of greatest interest.
The main contribution to the spread of radon is made by the so-called Dictyonema shales of the Lower Ordovician, places whose distribution is the most radon-hazardous territories in Russia. Dictyonema shales extend in a strip ranging from 3 to 30 km wide. from the city of Kingisepp in the west to the river. Sitting in the east, occupying an area of about 3000 square meters. km. Throughout its entire length, the shales are enriched in uranium, the content of which varies from 0.01% to 0.17%, and the total amount of uranium amounts to hundreds of thousands of tons. In the area of the Baltic-Ladoga ledge, the shales come to the surface, and to the south they plunge to a depth of a few tens of meters.
Since 1992, exposure emanation surveys have been carried out in the shale development area in order to identify radon-conducting zones and fields in the soil. On 18 reconnaissance profiles with a total length of 110.18 km, 5500 measurements were made. Background concentrations of radon in soil air are 15 Bq/l, which is three times higher than the regional background in the Leningrad region. At the same time, three levels of anomalous fields are clearly distinguished: the first 34-67 Bq/L (which accounts for 40.9% of the total length of the profiles), the second 68-135 Bq/L. (12.5% of the length of the profiles) and the third 136 Bq/l. and higher (2.8% of profile length).
It is expected that within radon-hazardous zones and fields with radon concentration in ground air above 67 Bq/l, covering an area of about 450 sq. km., the volumetric equivalent equilibrium activity of radon in rooms will exceed 100 Bq/cub.m., which causes effective annual radiation dose over 5 mSv per year. Such territories, in accordance with the current “Criteria for assessing the environmental situation of territories to identify zones of environmental emergency and zones of environmental disaster” (M., 1992), belong to territories of environmental emergency and the settlements located on them must be subjected to priority radiation examination for radon content in indoor air.
The conductors of radon underground are regional faults laid down in pre-Paleozoic times and faults activated in Meso-Kyonozoic times, with the help of which radon appears on the surface of the earth and is partially concentrated in loose layers of earth rocks.
Among the regions of Russia that are potentially dangerous in this sense are Western Siberia (Belokurikha, Novosibirsk), Transbaikalia (Krasnokamensk), the North Caucasus (Pyatigorsk) and the Northwestern regions of Russia.
The most powerful source of natural radionuclides, and in particular radon, into the atmosphere is energy enterprises operating on fossil fuels - coal, shale, oil:
Baltic thermal power plant operating on shale. Releases into the atmosphere with smoke emissions up to 90% of uranium, from 28 to 60% of radium and up to 78% of thorium. In addition to the aerosol component, emissions may contain up to 20% fly ash. As a result of the activities of the Baltic Thermal Power Plant, a zone of increased concentrations of natural radionuclides with a radius of approximately 40 heights of the station pipes formed around it. In this zone, there was an increase in the concentrations of natural radionuclides (RNN) by an order of magnitude for the top layer of soil (3 cm). The concentration of natural radionuclides in the plume is up to 50 µBq/cub.m of radium, up to 10 µBq/cub.m of thorium and up to 100 µBq/cub.m of uranium with a background of 1 µBq/cub.m of air.
The activities of PA "PHOSPHORITE" in the extraction of phosphorites lying below the Dictyonema shales, leading to the redistribution of uranium and its decay products from the Dictyonema shales, and the creation of tailings dumps on the banks of the Luga River lead to the fact that river waters carry radium-226 into the Luga Bay relatively intensively , where it is mainly deposited on the organic fraction of bottom sediments and iron-manganese nodules. The activities of PA "Phosphorit" concern mainly the area of the Luga River valley north of Kingisepp.
The main source of radon entering indoor air is the geological space under the building. Radon easily penetrates into rooms through permeable zones of the earth's crust. A building with a permeable floor, built on the earth's surface, can increase the flow of radon escaping from the ground up to 10 times due to the difference in air pressure between the building's rooms and the atmosphere. This difference is estimated on average to be about 5 Pa and is due to two reasons: the wind load on the building (the vacuum that occurs at the boundary of the gas stream) and the temperature difference between the room air and the atmosphere (the chimney effect).
The content of radon in indoor air depends on its content in the soil and underlying rocks, their emanating ability, the climatic conditions of the building structure and their ventilation system and the frequency of air exchange in the room. Radon concentrations and fluxes are extremely uneven; they vary within very wide limits for different regions and types of buildings. According to estimates by the International Commission on Radiation Protection (ICRP), the individual total radiation dose varies from 0.5 to 100 of the modal dose value, and it not only exceeds the dose limit for a limited part of the population from artificial radiation sources (1 mSv/year), but can also exceed the dose limit for professionals (20 mSv/year).
Its output from building structures also makes its contribution to the flow of radon entering the room - radon can be generated by building materials with a sufficiently high content of uranium and thorium in them. It is generated due to the fact that during the construction of the building, brick was used made from clay taken, say, from the Krasny Bor quarry, the clay of which is characterized by increased radioactivity - 150-300 Bq/kg. Also on the territory of the Leningrad region there are about 20 more deposits (quarries) for the extraction of non-metallic materials (granite, sand, clay, limestone.): Kamennogorsk quarry management, "Vozrozhdenie", JSC "Kampes", NWRP "Leningrad Port", etc. Aeff values . The NRN contained in these materials (crushed granite of various fractions, crushing screenings) have a significant scatter and are also characterized by increased radioactivity (200 - 700 Bq/kg).
In exceptional cases, the release of radon from tap water and household gas can contribute to the entry of radon into a room.
Radon-Ural
IN TERMS OF RADON POLLUTION, THE MIDDLE URAL RANKS SECOND PLACE IN RUSSIA
Let us recall that in January of this year, at a meeting of the Regional Government, the following data were announced: more than 2 million residents of the Middle Urals, which is almost half of the region’s residents, live in areas with increased background radiation. At the same time, 2/3 of the total dose of annual radioactive exposure of the population comes from radiation from radon and its fission products. In Yekaterinburg alone, 47% of the area falls into areas with varying degrees of radon hazard. According to the regional GOES, the Middle Urals ranks second in Russia in terms of radon pollution, second only to the Altai Territory.
All this data was obtained back in the mid-1990s. when carrying out special measurements. Based on them, a preliminary zoning map based on the degree of radon hazard was compiled. Thus, on the territory of Yekaterinburg, civil defense and emergency response specialists identified 7 radon hazardous zones. These include, for example, Sadovaya (north-eastern outskirts of the city), Koltsovskaya (Oktyabrsky district), Central, Shartashskaya (park area, Komsomolsky, Blue Stones, Izoplit), Severoshartashskaya (Shartash, Pionersky village). This situation is due to the geology of the area on which the city is located. According to the results of regional zoning, Yekaterinburg is located within the boundaries of the Verkhisetsky-Shartash ecological-radiochemical zone, characterized by a high rating of radon potential.
Radon is a colorless inert gas, odorless and tasteless, 7.5 times heavier than air. Various isotopes of radon are formed from the radioactive decay of uranium, radium and thorium in the earth's crust. Especially a lot of radon is released from granite rocks and phosphorites. Radon gradually seeps from the depths to the surface, where it immediately dissipates in the air, as a result of which its concentration remains negligible and does not pose a danger. However, accumulating in the basements and first floors of buildings, as well as in water, radon and its decay products in high concentrations can negatively affect human health.
This substance was first discovered by the English physicist E. Rutherford in 1900, who called it emanation (derived from the Latin word “outflow”). And the modern name “radon” was given to it by another Englishman, Dorn, in 1900, comparing it with the original radium. But radon is formed during the decay of not only radium, but also uranium, thorium, actinium and other radioactive elements.
1. Radon in nature
It is a noble gas, colorless and odorless, poisonous, and most importantly, radioactive. It easily dissolves in water, and even better in the fatty tissues of living organisms. Since radon is quite heavy (7.5 times heavier than air), it “lives” in the strata of the earth’s rocks, and, of course, is released little by little into the atmosphere. But not on its own, but in a mixture with the flows of other, lighter gases that carry it away - hydrogen, carbon dioxide, methane, nitrogen and others. All of them are generated by deep processes. An interesting fact is that radon, being an inert gas, does not form aerosols, i.e. does not attach to dust particles, heavy ions, etc. Due to its chemical inertness and long half-life, it can migrate through cracks, pores of soil and rocks over long distances, and for quite a long time (about 10 days). Radon is also found in some mineral waters, which are called radon waters.
2. Effect on living organisms
Only recently have scientists discovered that radon makes the greatest contribution to human radiation exposure. It is responsible for 3/4 of the annual radiation dose received by humans from terrestrial radiation sources and about half of this dose from all natural sources. It has been established that the main part of the radiation comes from the daughter products of the decay of radon - isotopes of lead, bismuth and polonium. Radon decay products enter the human lungs along with the air and are retained there. As they decay, they release alpha particles that infect epithelial cells. The decay of radon nuclei in lung tissue causes microburns, and increased concentrations of the gas in the air can lead to cancer. Alpha particles also cause damage to the chromosomes of human bone marrow cells, which increases the likelihood of developing leukemia. Unfortunately, the most important cells - reproductive, hematopoietic and immune - are most vulnerable to radon. Particles of ionizing radiation damage the hereditary code and, hiding, do not manifest themselves in any way until the time comes for the “sick” cell to divide or create a new organism - a child. Then we can talk about cell mutation, leading to disruptions in human life.
3. Radon in the house
Radon can enter a house in different ways: from the bowels of the Earth; from the walls and foundations of buildings, because building materials (cement, crushed stone, brick, cinder blocks) to varying degrees, depending on quality, contain a dose of radioactive elements; along with tap water and natural gas. Since this gas is heavier than air, it settles and concentrates in the lower floors and basements. The most significant way radon accumulates indoors is due to the release of radon from the soil on which the building stands. The greatest danger is the entry of radon with water vapor when using a shower, bath, or steam room. It is also found in natural gas, and therefore it is necessary to install a hood in the kitchen to prevent the accumulation and spread of radon. In 1995, our country adopted the federal law “On Radiation Safety of the Population” and special radiation safety standards are in force. It follows that when designing a building, the average annual activity of radon isotopes in the air should not exceed 80 Bq/m3 (becquerels per cubic meter). In residential apartments there is no more than 200 Bq/m3, otherwise the question arises of taking protective measures, and if the value reaches 400 Bq/m3, the building must be demolished or repurposed. Now many people purchase personal dosimeters to measure the general background radiation in the apartment. But it is useless for measuring radon levels; here you need to call specialists with a radon radiometer. If you want to protect your home from harmful gases yourself, you should seal cracks in the walls and floors, hang wallpaper, seal the basement and simply ventilate the rooms in your house more often. I note that the concentration of radon in an unventilated room is 8 times higher.
4. Benefits of radon
But there is nothing superfluous in nature, and in addition to important research in the field of chemistry and physics, radon is used in many areas of human life. It is used in medicine to prepare “radon baths”, in agriculture to activate pet food, in metallurgy as an indicator for determining the speed of gas flows in blast furnaces and gas pipelines. Geologists use it to find deposits of radioactive elements. Seismologists, by analyzing the release of radon from soils, can predict strong earthquakes and volcanic eruptions. Therefore, with successful and timely protective measures, even such a “chimera” can be made to serve humanity.
In light of the rapid development of science and technology, experts express concern about the lack of promotion of radiation hygiene among the population. Experts predict that in the next decade, “radiological ignorance” could become a real threat to the safety of society and the planet.
The Invisible Killer
In the 15th century, European doctors were baffled by the abnormally high mortality rate from pulmonary diseases among workers in mines extracting iron, base metals and silver. A mysterious illness called “mountain sickness” affected miners fifty times more often than the average person. Only at the beginning of the 20th century, after the discovery of radon, was it recognized as the cause of stimulating the development of lung cancer among miners in Germany and the Czech Republic.
What is radon? Does it only have a negative effect on the human body? To answer these questions, we should recall the history of the discovery and study of this mysterious element.
Emanation means "flowing out"
The English physicist E. Rutherford is considered to be the discoverer of radon. It was he who noticed in 1899 that thorium-based preparations, in addition to heavy α-particles, emit a colorless gas, leading to an increase in the level of radioactivity in the environment. The researcher called the supposed substance an emanation of thorium (from emanation (Latin) - outflow) and assigned it the letter designation Em. Similar emanations are also inherent in radium preparations. In the first case, the emitted gas was called thoron, in the second - radon.
Later it was possible to prove that the gases are radionuclides of the new element. It was first isolated in its pure form by the Scottish chemist, Nobel laureate (1904) William Ramsay (together with Whitlow Gray) in 1908. Five years later, the element was finally assigned the name radon and the symbolic designation Rn.
In the chemical elements of D.I. Mendeleev, radon is in the 18th group. Has atomic number z=86.
All existing isotopes of radon (more than 35, with mass numbers from 195 to 230) are radioactive and pose a certain danger to humans. There are four types of atoms of an element found in nature. All of them are part of the natural radioactive series of actinouranium, thorium and uranium - radium. Some isotopes have their own names and, according to historical tradition, are called emanations:
- sea anemone - actinone 219 Rn;
- thorium - thoron 220 Rn;
- radium - radon 222 Rn.
The latter is the most stable. radon 222 Rn - 91.2 hours (3.82 days). The steady state time of the remaining isotopes is calculated in seconds and milliseconds. When alpha particles decay with radiation, polonium isotopes are formed. By the way, it was during the study of radon that scientists first encountered numerous varieties of atoms of the same element, which were later called isotopes (from the Greek “equal”, “same”).
Physical and chemical properties
Under normal conditions, radon is a colorless and odorless gas, the presence of which can only be determined with special instruments. Density - 9.81 g/l. It is the heaviest (air is 7.5 times lighter), the rarest and most expensive of all gases known on our planet.
It is highly soluble in water (460 ml/l), but the solubility of radon in organic compounds is an order of magnitude higher. It has a fluorescence effect caused by its own high radioactivity. The gaseous and liquid state (at temperatures below -62˚С) is characterized by a blue glow, while the crystalline state (below -71˚С) is yellow or orange-red.
The chemical characteristics of radon are determined by its belonging to the group of inert (“noble”) gases. It is characterized by chemical reactions with oxygen, fluorine and some other halogens.
On the other hand, the unstable nucleus of an element is a source of high-energy particles that affect many substances. Exposure to radon causes staining of glass and porcelain, decomposes water into oxygen, hydrogen and ozone, destroys paraffin and petroleum jelly, etc.
Getting radon
To isolate radon isotopes, it is enough to pass a stream of air over a substance containing radium in one form or another. The gas concentration in the stream will depend on many physical factors (humidity, temperature), on the crystal structure of the substance, its composition, porosity, homogeneity and can range from small fractions to 100%. Usually solutions of radium bromide or radium chloride in hydrochloric acid are used. Solid porous substances are used much less frequently, although radon is released more pure.
The resulting gas mixture is purified from water vapor, oxygen and hydrogen by passing it through a hot copper mesh. The remainder (1/25,000 of the original volume) is condensed and impurities of nitrogen, helium and inert gases are removed from the condensate.
For note: throughout the world, only a few tens of cubic centimeters of the chemical element radon are produced per year.
Distribution in nature
Radium nuclei, the fission product of which is radon, are in turn formed during the decay of uranium. Thus, the main source of radon is soils and minerals containing uranium and thorium. The highest concentrations of these elements are in igneous, sedimentary, metamorphic rocks, and dark-colored shales. Radon gas, due to its inertness, easily leaves the crystal lattices of minerals and easily spreads over long distances through voids and cracks in the earth's crust, releasing into the atmosphere.
In addition, interstratal groundwater, washing such rocks, is easily saturated with radon. Radon water and its certain properties were used by man long before the discovery of the element itself.
Friend or foe?
Despite thousands of scientific and popular science articles written about this radioactive gas, there is no clear answer to the question: “What is radon and what is its significance for humanity?” seems difficult. Modern researchers face at least two problems. The first is that in the sphere of influence of radon radiation on living matter, it is both a harmful and beneficial element. The second is the lack of reliable means of registration and monitoring. The existing radon detectors in the atmosphere, even the most modern and sensitive ones, when repeated measurements can produce results that differ several times.
Beware of radon!
A person receives the main dose of radiation (more than 70%) in the process of life thanks to natural radionuclides, among which the leading position belongs to the colorless gas radon. Depending on the geographical location of the residential building, its “contribution” can range from 30 to 60%. A constant amount of unstable isotopes of a dangerous element in the atmosphere is maintained by a continuous supply from earth rocks. Radon has the unpleasant property of accumulating inside residential and public buildings, where its concentration can increase tens or hundreds of times. The danger to human health is not so much the radioactive gas itself, but rather the chemically active isotopes of polonium 214 Po and 218 Po, formed as a result of its decay. They are firmly retained in the body, having a detrimental effect on living tissue by internal α-radiation.
In addition to asthmatic attacks of suffocation and depression, dizziness and migraines, this is fraught with the development of lung cancer. The risk group includes workers of uranium mines and mining and processing plants, volcanologists, radon therapists, the population of unfavorable areas with a high content of radon derivatives in the earth's crust and artesian waters, and radon resorts. To identify such areas, radon hazard maps are compiled using geological and radiation-hygienic methods.
For a note: it is believed that it was exposure to radon that provoked the death of the Scottish researcher of this element, William Ramsay, from lung cancer in 1916.
Methods of protection
In the last decade, following the example of its Western neighbors, the necessary anti-radon measures began to spread in the countries of the former CIS. Regulatory documents have appeared (SanPin 2.6.1., SP 2.6.1.) with clear requirements to ensure radiation safety of the population.
The main measures to protect against soil gases and natural sources of radiation include:
- Arrangement of a monolithic concrete slab with a crushed stone base and reliable waterproofing on an earthen underground wooden floor.
- Providing enhanced ventilation of basement and basement spaces, ventilation of residential buildings.
- Water entering kitchens and bathrooms must undergo special filtration, and the premises themselves must be equipped with forced exhaust devices.
Radiomedicine
Our ancestors did not know what radon was, but even the glorious horsemen of Genghis Khan healed their wounds with the waters of the Belokurikha (Altai) springs, saturated with this gas. The fact is that in microdoses radon has a positive effect on vital human organs and the central nervous system. Exposure to radon waters accelerates metabolic processes, due to which damaged tissues are restored much faster, the functioning of the heart and circulatory system is normalized, and the walls of blood vessels are strengthened.
Resorts in the mountainous regions of the Caucasus (Essentuki, Pyatigorsk, Kislovodsk), Austria (Gastein), Czech Republic (Jachimov, Karlovy Vary), Germany (Baden-Baden), Japan (Misasa) have long enjoyed well-deserved fame and popularity. Modern medicine, in addition to radon baths, offers treatment in the form of irrigation and inhalation under the strict supervision of an appropriate specialist.
In the service of humanity
The scope of radon gas is not limited to medicine. The adsorption ability of element isotopes is actively used in materials science to measure the degree of heterogeneity of metal surfaces and decoration. In steel and glass production, radon is used to control the progress of technological processes. It is used to test gas masks and chemical protective equipment for leaks.
In geophysics and geology, many methods for searching and detecting deposits of minerals and radioactive ores are based on the use of radon surveys. The concentration of radon isotopes in the soil can be used to judge the gas permeability and density of rock formations. Monitoring the radon situation looks promising in terms of predicting upcoming earthquakes.
We can only hope that humanity can still cope with the negative effects of radon and that the radioactive element will only bring benefits to the planet’s population.
Content:What do the phrases mean in practice: “radon baths”, “radon therapy”, “radon treatment” - does this element, studied in school chemistry lessons, bring benefit or harm? How is radon obtained for treatment and how often can it be used so as not to harm the body? The gas is used in radon therapy to improve health.
What is radon
Radon belongs to the group of inert gases, has no odor, color or taste, and can fluoresce - at first it was called niton, from the Latin “luminous”. Fluorescence color changes depending on the state from blue to yellow-orange (when cooled).
Known as a medicinal product, the gas is a radioactive substance and, if used improperly, can be harmful to health and life. It all depends on the concentration, but even knowing it, you cannot self-medicate: it has contraindications and individual intolerance to certain organisms.
Although radon forms deep in the earth and, being heavy, cannot rise to the surface on its own, it quickly “clings” to lighter gases or dissolves in water and rises closer to the surface. Natural radon caves or baths are based on this property, in the likeness of which artificial ones are created, forcibly saturated with gas.
It is one of the rarest gases in nature. Its amount in the air and in the earth's crust is minimal; it is formed during the decay of radium, an equally rare substance. In radium deposits, gas is constantly formed; a small amount of the substance is enough for the uninterrupted functioning of a radon clinic.
At the service of man
For almost a century after its official discovery, radon has been used in many areas of life: when raising domestic animals, radiation helps to find deposits of radioactive elements, and is used in many technological processes.
It has found its most significant application in medicine; since the last century, sanatoriums with radon baths have been in demand, and many resorts have become popular all over the world due to the saturation of waters with this radioactive substance.
Microdoses of radon, dissolved in mineral waters intended for baths or inhalations, penetrating inside the human body, have a healing effect on almost all systems: from the nervous to the circulatory. A small amount of radon is quickly eliminated from the body without causing harm.
The history of the discovery of the element is rich in ups and downs. It has long been noted that some springs have a healing effect, but only at the beginning of the twentieth century was science able to substantiate this, and already in 1911 a resort began operating in the city of Jáchymov, Czech Republic, which later became one of the most popular.
In Russia, the pioneer in the field of radon therapy was the hospital in Belokurikha, founded in 1867. 40 years later, in 1907, research confirmed that the waters of the hospital have healing properties due to their radon content.
Today, one of the most popular resort cities in Russia that uses healing gas is Pyatigorsk. Water hospitals were built here even when the concept of radioactivity was not formulated. Observations showed the healing properties of the waters in this region, and in the middle of the 19th century, the first buildings began to be built here, which later housed baths.
Today, numerous sanatoriums in the city use radioactive therapy to treat and improve the health of vacationers. Science studying the effects of gas on human health was officially born here; the radon baths of Pyatigorsk became one of the attractions, a kind of calling card.
Impact principle
The therapy is used to treat a wide range of diseases, baths allow the gas to penetrate the body first through the skin and then into the subcutaneous layers, where it dissolves in fatty tissues or penetrates deeper into organs. Under its influence, an ionization effect occurs, which activates internal processes, restores balance and activates regeneration mechanisms.
A course of radon treatment improves the condition of the skin, reduces inflammation, promotes metabolism and accelerates the restoration of damaged internal tissues. It has a special effect on the circulatory system: it affects vessels from the smallest to the largest, improves blood circulation and increases the elasticity of the walls, affecting the functioning of the heart muscle, normalizing the pulse rate.
It is necessary to note the effect of gas on the nervous system: it calms and relaxes, can be used for sleep disorders and to relieve pain.
A positive effect has been noticed in pulmonary and joint diseases, and is used for weight loss, which has become especially important recently. To achieve a noticeable result, the method must be combined with physical activity, monitor your diet, giving preference to healthy foods. The healing effect of radon procedures lasts up to six months.
In gynecology
Due to its anti-inflammatory effect, radon is indicated for gynecological diseases. Baths and irrigations are used that act directly on the area of inflammation, help tissues recover, and can stop bleeding, although this is not recommended. Radioactive gas is used to treat:
- fibromatosis;
- polycystic ovary syndrome;
- fibroids;
- endometriosis and other diseases.
In some cases, a positive effect was found on the normalization of the female cycle, reduction of pain syndromes, and improvement in menopausal ailments. Scientists noted that radon is so effective in gynecology that it can often replace surgical methods, especially in the treatment of fibroids.
Therapy methods
Depending on the disease, medicine offers several ways to influence the body with radon.
Baths are the most popular, they have a healing effect for a specific disease and heal the body as a whole. They are prescribed in a course, combined with massage and mud therapy; usually 12-15 procedures are performed, depending on the doctor’s prescription. The bath temperature is approximately 36 degrees, the duration of the procedure is 10-20 minutes.
Due to the fact that radon exposure normalizes blood pressure, this method is common for treating patients who cannot use other methods due to the danger of increasing blood pressure. For older people suffering from joint pain and unstable blood pressure, radon therapy is an excellent alternative to drug treatment.
For diseases of the digestive system, it is more advisable to drink, for “female” diseases - irrigation or microenemas. Drinking therapy is indicated for those suffering from gout - the metabolism of uric acid improves, since radon normalizes the functioning of the liver and other internal organs.
It can be used to treat the respiratory tract; in this case, radon adits or so-called air baths are used. Adits are understood as natural caves with the most suitable level of radon content. They maintain high levels of humidity and temperature, which allows the pores to open. Air baths are artificially created devices that produce the effect of natural adits.
In many countries there are sanatoriums with artificial radon baths. For diseases associated with the musculoskeletal system, it is possible to prescribe oils enriched with radon. The Czech resort offers treatment with so-called radon boxes in cases where longer exposure is required. This method, called brachyradiumtherapy, can be used by adults over 18 years of age under medical supervision.
Contraindications
Has a number of contraindications:
- pregnancy, some types of infertility, decreased ovarian function;
- malignant formations;
- hypothyroidism, hypoestrogenia, severe leukopenia;
- radiation sickness at any stage;
- professional activities related to radiation (UHF, microwave, etc.);
- feverish conditions;
- skin diseases during exacerbation;
- severe neuroses;
- with caution in case of thyroid disorders.
The use of radon therapy is permitted for children over 5 years of age as prescribed by a specialist.
Benefit or harm
Radon was discovered at the beginning of the twentieth century and very quickly aroused widespread interest. Its effect on the body was studied, and radioactivity and saturation with the substance became a guarantee of the effectiveness of mineral water. A peculiar fashion for radioactivity arose; in the wake of interest, the use of gas for medical purposes was widely promoted.
By the 1920s, it became clear that in small doses the substance has a very beneficial effect on the body, often for diseases that are difficult to treat with other methods. It is used in the treatment of the spine, joint and immune diseases, varicose veins, relieves tension in the nervous system, relaxing and calming, helps in the fight against excess weight and unstable blood pressure. Relieves pain for a long time, including during menopause in women.
It would seem that what is not a panacea? However, everything that exists has two sides. Recent studies have revealed that the beneficial gas, which has served human health for more than a century, is one of the causes of lung cancer. The culprit is the elements that settle in the body after the decay of the gas and intensively irradiate it.
Often people suffer from radiation without noticing it: the gas may be contained in building materials or simply released from the bowels of the earth in the place where the house is built. Therefore, today in our country, as in many others, radon content standards have been established, which are measured with special devices. If these standards are exceeded, measures are taken to reduce it or the house is demolished if the indicators reach critical heights.
In small concentrations, radon remains an indispensable medicine that comes to the rescue when other options are contraindicated. It is necessary to remember the dosage and follow the doctor's instructions.
The radioactive gas radon is constantly and everywhere released from the thickness of the Earth. Radon radioactivity is part of the radioactive background of the area.
Radon is formed at one of the stages of the breakdown of radioactive elements contained in earth rocks, including those used in construction - sand, crushed stone, clay and other materials.
Radon is an inert gas, colorless and odorless, 7.5 times heavier than air. Radon provides approximately 55-65% of the radiation dose that every inhabitant of the Earth receives annually. The gas is a source of alpha radiation, which has low penetrating ability. A sheet of Whatman paper or human skin can serve as a barrier to alpha radiation particles.
Therefore, a person receives most of this dose from radionuclides that enter his body along with the inhaled air. All isotopes of radon are radioactive and decay quite quickly: the most stable isotope Rn(222) has a half-life of 3.8 days, the second most stable isotope Rn(220) has a half-life of 55.6 seconds.
Radon, having only short-lived isotopes, does not disappear from the atmosphere, since it constantly enters it from earthly sources; breeds The loss of radon is compensated by its supply, and a certain equilibrium concentration exists in the atmosphere.
For people, an unpleasant feature of radon is its ability to accumulate indoors, significantly increasing the level of radioactivity in places of accumulation. In other words, the equilibrium concentration of radon indoors can be significantly higher than outside.
The sources of radon entering the house are shown in Fig. 1. The figure also shows the power of radon radiation from a particular source.
The radiation power is proportional to the amount of radon. From the figure it is clear that The main source of radon entering the house is building materials and soil under the building.
Building regulations regulate the radioactivity of building materials and provide for monitoring compliance with established standards.
The amount of radon released from the soil under a building depends on many factors: the amount of radioactive elements in the earth, the structure of the earth’s crust, gas permeability and water saturation of the upper layers of the earth, climatic conditions, building design and many others.
The highest concentration of radon in the air of residential premises is observed in winter.
A building with a permeable floor can increase the flow of radon escaping from the ground beneath the building by up to 10 times compared to an open area. The increase in flow occurs due to the difference in air pressure at the boundary of the soil and the premises of the building. This difference is estimated on average to be about 5 Pa and is due to two reasons: the wind load on the building (a vacuum that occurs at the boundary of the gas stream) and the temperature difference between the air in the room and the air at the boundary of the ground (the chimney effect).
Therefore, building codes require the protection of buildings from the entry of radon from the soil under the building.
Figure 2 shows a map of Russia indicating areas of potential radon hazard.
Increased release of radon in the areas indicated on the map does not occur everywhere, but in the form of foci of varying intensity and size. In other areas, the presence of point centers of intense radon release is also possible.
Radiation monitoring is regulated and standardized by the following indicators:
- exposure dose rate (EDR) of gamma radiation;
- average annual equivalent equilibrium volumetric activity (ERVA) of radon.
DER gamma radiation:
- when allocating a land plot, it can be no more than 30 microR/hour;
- when putting a building into operation and in existing buildings - should not exceed the dose rate in open areas by more than 30 microR/hour.
EROA of radon should not exceed:
— in buildings put into operation — 100 Bq/m 3(Becquerels/m3);
When allocating a land plot, the following is measured:
— DER gamma radiation (gamma background);
— EROA content of soil radon.
Radiation monitoring indicators are usually determined during pre-design surveys of the construction site. According to current legislation, local authorities must transfer a plot of land to a citizen for individual housing construction after conducting radiation monitoring, provided that the indicators comply with established sanitary standards.
When purchasing a plot of land for development, you should ask the owner whether radiation monitoring has been carried out and its results. In any case, the private developer especially when the site is located in a potentially hazardous area for radon (see map), you need to know the radiation monitoring indicators at your site.
Local district administrations should have maps of radon-hazardous areas in the region. If information is missing, tests should be ordered from local laboratories. By teaming up with your neighbors, you can usually reduce the cost of doing this work.
Based on the results of assessing the radon hazard of the construction site, measures to protect the house are determined. The extent to which a person is exposed to radiation depends on the power of the radiation (amount of gas) and the duration of exposure.
In the case of radon, first of all, residential premises on the first and basement floors, where people stay for a long time, should be protected.
Outbuildings and premises - basements, bathrooms, baths, garages, boiler rooms - must be protected from radon to the extent that gas can penetrate from these premises into living rooms.
Ways to protect your home from radon
To protect residential premises from radon, install two lines of defense:
- Execute gas insulation enclosing building structures, which prevents the penetration of gas from the ground into the premises.
- Provide ventilation space between the ground and the protected room. Ventilation reduces the concentration of harmful gas at the boundary of the soil and the room, before it can penetrate into the premises of the house.
To reduce the entry of radon into residential floors Perform gas insulation (sealing) of building structures. Gas insulation is usually combined with waterproofing of the underground and basement parts of the building. This combination does not cause difficulties, since the materials used for waterproofing usually act as a barrier to gases.
A vapor barrier layer can also serve as a barrier to radon. It should be noted that polymer films, especially polyethylene, transmit radon well. Therefore, as a gas-hydro-vapor barrier for the basement of the building, it is necessary to use a polymer - bitumen roll materials and mastics.
Gas-waterproofing is usually installed at two levels: at the soil-building boundary and at the level of the basement floor.
If the house has a basement that is used for long-term stays of people or there is an entrance to the basement from the residential part of the first floor, then gas-waterproofing of the basement surfaces should be performed in a reinforced version.
In a house without a basement, with floors on the ground, gas and waterproofing is carefully carried out at the level of the ground floor preparation structures.
Developer! When choosing waterproofing options, remember the need to gas insulate your home from radioactive radon!
High-quality gas-waterproofing is carried out by gluing structures with special waterproofing materials. The joints of rolled gas-waterproofing materials laid dry must be sealed with adhesive tape.
Gas-waterproofing of horizontal surfaces must be hermetically sealed with a similar coating of vertical structures. Particular attention is paid to careful sealing of passages through ceilings and walls of communication pipelines.
A gas insulation barrier due to construction defects and damage to integrity during subsequent use of the building may not be sufficient to protect the building from soil radon.
That's why, Along with gas insulation, a ventilation system is used. A ventilation device can also reduce the requirements for gas insulation, which will reduce the cost of construction.
To protect against soil radon, arrange, located under protected from radon indoors. Such ventilation intercepts harmful gas on its way to the protected area, up to the gas insulation barrier. In the space in front of the gas insulation barrier, the gas pressure is reduced or even a vacuum zone is created, which reduces and even prevents the flow of gas into the protected room.
Such a radon-intercepting ventilation system is also needed because conventional exhaust ventilation in protected areas draws in air from outside the room, increasing the flow of radon from the ground if there are defects in the gas insulation.
To protect operating basements or first floors of buildings from radon, exhaust ventilation of the space under the concrete floor preparation is arranged, Fig. 3.
To do this, a captage pillow with a thickness of at least 100 is made under the floor. mm. made of crushed stone, a receiving pipe with a diameter of at least 110 is inserted into the catchment pad mm. ventilation exhaust duct.
A drip cushion can also be made on top of a concrete floor preparation, for example, from expanded clay, mineral wool slabs or other gas-permeable insulation, thereby providing thermal insulation for the floor. A prerequisite in this option is the installation of a gas-vapor barrier layer on top of the insulation.
If the basement space under the floor of the first floor is uninhabited or rarely visited, then an example of an exhaust ventilation device for protection against radon on the first floor in this case is shown in Fig. 4.
A layer of polymer-bitumen roll gas-waterproofing will reduce the flow of ground moisture into the subfloor and reduce heat loss through the ventilation system in winter, without reducing the effectiveness of protection against soil gases.
In some cases, there is a need to increase the efficiency of exhaust ventilation by integrating an electric fan, usually of low power (about 100 W.). The fan can be controlled from a radon sensor installed in the protected room. The fan will turn on only when the radon concentration in the room exceeds the set value.
For a house with a total ground floor area of up to 200 m 2 One exhaust ventilation channel is sufficient.
In accordance with sanitary standards, the content of radon in premises must be monitored in school buildings, hospitals, child care institutions, when commissioning residential buildings, and in industrial premises of enterprises.
Before starting construction of a house, take an interest in the results of radon monitoring in the buildings closest to your site. This information may be available from building owners, local laboratories that carry out measurements, Rospotrebnadzor authorities, and local design organizations.
Find out what radon control measures were used in these buildings. If the design of your home does not have a section on protection from radon, this knowledge will help you choose a fairly effective and cost-effective protection option.
Reducing the concentration of radon entering the protected premises from other sources: water, gas and outside air is ensured by conventional exhaust ventilation systems from the premises of the house.
The gas is easily adsorbed by filters with activated carbon or silica gel.
Upon completion of the construction of the house, take control measurements of the radon content in the premises, make sure that protection against radon ensures the safety of your family.
In Russia, the problem of protecting people in buildings from radon has only recently become a concern. Our fathers, and even more so our grandfathers, did not know about such a danger. Modern science claims that radon radionuclides have a strong carcinogenic effect on human lungs.
Among the causes of lung cancer, inhalation of radon contained in the air is in second place in terms of danger after smoking tobacco. The combined effect of these two factors - smoking and radon, dramatically increases the likelihood of this disease.
Give yourself and your loved ones a chance to live longer - protect your home from radon!