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Article

Study of Radon Radiation in the Area of the Akchatau Polymetallic Mine, Republic of Kazakhstan

by
Yuriy Pak
1,
Dmitriy Pak
1,*,
Vladimir Matonin
2,
Diana Ibragimova
1,
Pavel Timoshenko
2,
Yuriy Barkov
2,
Anar Tebayeva
1 and
Pavel Medvedev
2
1
Department of Geology and Mineral Exploration, Abylkas Saginov Karaganda Technical University NJSC (KTU), Karaganda 100026, Kazakhstan
2
Ecoexpert LLP, Karaganda 100008, Kazakhstan
*
Author to whom correspondence should be addressed.
Atmosphere 2025, 16(7), 769; https://doi.org/10.3390/atmos16070769
Submission received: 23 March 2025 / Revised: 19 May 2025 / Accepted: 14 June 2025 / Published: 23 June 2025
(This article belongs to the Section Air Quality)
Browse Figures
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Abstract

The data on the volumetric radon activity of the Akchatau territory were systematized in the context of radioecological safety. Radon (Rn222 and Rn220) and indoor radon (isotopes Po, Pb, and Bi) make a significant contribution to radon radiation in residential and industrial premises. Increased radon concentration in a number of areas is associated with the Akchatau tungsten–molybdenum mine. The source of radon in geological terms is acid leucocratic granites in the northwestern and southeastern parts of the studied territory. Seasonal assessment of radon radiation was carried out using modern devices “Alfarad Plus” and “Ramon-Radon”. Frequency analysis of the average annual equivalent equilibrium concentration (EEC) in 181 premises showed that only in 47.5% of the premises does the volumetric radon activity not exceed the current standards (200 Bq/m3). Differentiated values of radon concentration were obtained in cases where daily and seasonal observations were carried out. In 43.1% of premises, the effective dose varies from 6.6 mSv/year to 33 mSv/year, and for 9.4% of premises, from 33 mSv/year to 680 mSv/year. The increased radon concentration is caused by high exhalation from the soil surface, the radioactivity of building materials, and low air exchange in the surveyed premises. In the northwestern part of Akchatau, anomalous zones were found where the exposure dose rate of gamma radiation exceeds 0.6 mkSv/hour. An objective assessment of radon largely depends on a number of factors that take into account the geological, technical, atmospheric, and climatic conditions of the region. Therefore, when planning an optimal radon rehabilitation strategy, it is necessary to take the following factors into account: the design features of residential premises and socio-economic conditions. Practical recommendations are given for radiation-ecological and hygienic monitoring of radon safety levels in the environment to reduce effective doses on the population.

1. Introduction

Radon (Rn222 and Rn220) and indoor radon (isotopes Po, Pb, and Bi) make the main contribution to the radionuclide background of residential and industrial premises [1,2,3,4,5]. Radon is an inert, odorless, and tasteless gas formed as a result of the decay of radium. There are three natural alpha-active isotopes of radon belonging to the radioactive family, U238, Th232, and U235 (Rn222, Rn220, and Rn219), with half-lives of 3.8 days, 55 s, and 3.9 s, respectively. The sources of radon entering the atmosphere are thermal power plants operating on organic fuel (coal, shale, and oil), as well as the release of gaseous decay products of natural radioactive elements from the soil, including volcanic activity on land and in the oceans. In addition to these sources, several other sources can be noted, collected in Table 1 [2,6].
The indoor radon radiation level reflects the balance between the radon input into the room from all sources and its loss due to radioactive decay and dilution through ventilated air [7,8]. In other words, the radon accumulation rate represents the contribution from soil gas, drinking water, emissions from building materials, coal combustion, and gas used in households.
According to the Scientific Committee on the Effects of Atomic Radiation (SC AER), the effective radiation dose of 1 mSv/year is on average approximately half the radiation dose of people from all the natural radioactive elements. At least 10% of lung cancer cases registered annually in the world are caused by radon radiation [5].
Elevated radon concentrations pose a health hazard to humans. According to WHO, radon is responsible for 3–14% of lung cancer cases, depending on the average radon concentration level in a country [9,10]. In many countries, it is considered the main cause of lung cancer in non-smokers [11,12].
The negative impact of radon on human health has led to the introduction of permissible radon levels in countries such as the United States (148 Bq/m3), Canada, Norway (100 Bq/m3), and the EU countries (300 Bq/m3). In Kazakhstan, the permissible level is 200 Bq/m3. In addition to the level of radon exposure, countries need to determine the areas that are most susceptible to radon exposure to identify the areas where the predicted radon concentration in most buildings will exceed the permissible radon level. The collective radiation dose for the population of Russia caused by natural sources of ionizing radiation is 50 million manSv/year, which is more than 300 times higher than the collective dose due to the Chernobyl accident [13,14,15]. In a number of countries around the world, there are territories classified as radon-hazardous zones, where radon accounts for more than 50% of the collective radiation dose of the population [16]. According to [17], radon action levels are recommended values in all countries, and the most common are 400 and 200 Bq/m3. Switzerland has a mandatory limit of 1000 Bq/m3 and a building standard of 400 Bq/m3. Norway also has a limit of 100 Bq/m3. In most countries, the target level for new buildings is only a recommendation, but in Finland, Norway, and Sweden, it is mandatory and specified in building codes. In France, the mentioned action level only applies to some public buildings. In the countries of the European Union, the recommended reference levels for radon activity are 200 Bq/m3 for new residential buildings and 400 Bq/m3 for old ones.
In general, radon zones are very different, so various factors are taken into account: gamma radiation dose rate, geology and fault lines, permeability of the upper soil layer, and correlation between indoor radon and geology [18,19,20,21,22,23]. Indoor radon levels may vary with seasonal changes, as climate change affects indoor and outdoor air differently [24,25]. Radon has a high density (9.73 g/L under normal conditions), which, combined with its inertness and low mobility, contributes to its retention in indoor air. The main reason for the increase in radon concentration is not its mass, but limited air exchange renewal and the presence of a constant source of radon from the underlying soil.
The main sources of radon (Rn222) in indoor air are its entry from the soil under the building and from building materials. In this regard, in multi-story buildings, the highest radon content is observed in basements and ground floor rooms.
Recently, many researchers have shown interest in studying the effects of radon on human health [26,27]. The World Health Organization (WHO) has developed recommendations for measuring radon concentrations worldwide based on data collected by the United Nations Atomic Energy Committee on the Effects of Atomic Radiation [5]. A study conducted in Brazil showed that there is a close relationship between geological and climatic features and the level of radon in the air [28]. In poorly ventilated areas, radon and its decay products can accumulate in quantities tenfold compared to outside air [3,4,29].
An example of a high level of radon manifestation in mine workings and in residential premises in Kazakhstan is the Akchatau mine (Figure 1). A comprehensive survey of radon concentrations in the mine shafts and residential premises was conducted at the mine. The incidence of diseases of the respiratory system, nervous system, and circulatory system exceeds the average for the region by 2.9 times, which indicates the negative impact of radon.
It can be seen from the diagram that part of the territory of the Karaganda region is classified as radon hazardous. The bulk of the research was carried out in the village of Akchatau, since the most dangerous radiation situation was identified there. It arose in connection with the development of tungsten and molybdenum deposits (Akchatau deposit). Until 1991, tungsten and molybdenum ores were mined by the mine method. The deposit is located in the western part of the Akchatau massif and belongs to the greisen group. The main mass of greisen bodies is located in the endocontact part of the granite massif and in adamellites. The deposit is located in a complex structural-tectonic setting near uranium ore and rare metal–uranothorium structural–metallogenic zones (Figure 1). In general, there is a significant relationship between radon concentration and geological factors [30].
In the Akchatau area, underground mining was carried out using the shaft method. Geological exploration and mining operations were carried out at a considerable depth, with the creation of a system of mine workings and ventilation shafts. This man-made factor, in our opinion, could have affected increasing permeability of the geological environment near the surface due to the deformation of rocks, the appearance of cracks, and possible subsidence. Similar processes are described in the scientific literature, where underground operations led to the formation of new migration routes for radon from deep horizons [31,32,33]. The depth of mine workings at the Akchatau mine ranges from 25 to 120 m. This corresponds to the category of near-surface mines, at which the anthropogenic impact on the geological environment is maximized. Such depths are characteristic of areas of increased radon hazard, as shown in the coal basins of Poland, China, and Russia. Under such conditions, channels of vertical radon migration to the surface are created, including in residential buildings, even those located outside the direct projection of the mine mouth.
According to the UN National Committee for Atomic Resources, radon and all of its daughter products account for approximately 75% of the annual individual equivalent dose of radiation received by the population from natural sources of radiation [16,34,35]. Moreover, the contribution of Rn222 is approximately 20 times higher than the contribution of Rn220. Internal radon Rn222 is associated with the radionuclides Po, Pb, and Bi. A person spends on average up to 80% of the time indoors, inevitably being exposed to stronger effects of radon isotopes than outside the building. The problem of radon hazard is very relevant for Kazakhstan. In areas of Kazakhstan with normal levels of natural background radiation, the content of Rn222 in the air of residential premises averages 30–40 Bq/m3, which is close to the world average. However, the range of variation in the concentration of Rn222 is quite large, from 3 to 8500 Bq/m3. The level of radon study in Kazakhstan is currently comparatively low. On a regional scale, selective studies were mainly conducted [34,35,36,37].
Geological factors can also affect radon accumulation (Table 2).
Studies have shown that radon concentrations vary depending on the season. High levels of radon contamination have also been detected on the ground floors and in the basements. In general, the problem of elevated radon levels in the Akchatau area, where about 1200 people currently live, has not been addressed in detail. The mine has now been closed, but the radon hazards for the local population remain.
Misunderstanding of radon radiation problems gives rise to unfounded radiophobia about non-existent dangers on the one hand and to ignoring the real radiation threats to health on the other. Based on the above, the purpose of this study is to assess radon levels in residential buildings in the Akchatau settlement of the Karaganda region, identify geological and anthropogenic factors that contribute to its elevated levels, and analyze the potential effective dose on the population.

2. Materials and Methods

The village of Akchatau, located in the Karaganda region, is characterized by a high level of indoor radon concentrations in the air of premises, established by the results of a number of accompanying and special studies. Until 1991, tungsten and molybdenum ores were mined by the shaft method. Akchatau harbors a high-temperature hydrothermal tungsten–molybdenum deposit that belongs to the greisen group. The geological structure of the ore field (Figure 2) includes the Silurian terrigenous formations (sandstones, siltstones, and shales), which have high permeability and facilitate vertical migration of radon, as well as the Lower Carboniferous volcanic rocks (andesites, dacites, liparites, their tuffs, and lavas). The host strata are intruded by rocks of acidic composition: adamelites and alaskite granites of the Permian age. Granite is radioactive because it contains long-lived natural radioactive isotopes: U238, U235, Th232, and K40, as well as almost all of their decay products, including radon. The Akchatau district is characterized by the presence of large tectonic faults, including faults and fault-slips with a displacement amplitude of more than 1 km, as well as small shifts with an amplitude of tens and hundreds of meters. These faults form channels through which radon can migrate from deep horizons to the surface. The Akchatau district is crossed by a network of tectonic faults of varying depth and power. Some of them are deep faults penetrating into the earth’s crust to significant depths. This process is enhanced in fault intersection zones and in areas where rocks have fracture permeability, for example, the West Dzhungar fault located in Central Kazakhstan. Such faults can serve as channels for vertical migration of radon [39]. Permeable cover deposits (sandy loam, sand) that are typical for part of the territory of Akchatau do not prevent radon migration but, on the contrary, facilitate its entry into the lower levels of buildings. A loose fit of the foundation to the ground, cracks in concrete slabs, gaps in ceilings, as well as utility lines (pipelines, ventilation shafts) create pathways for radon penetration into residential premises. This process is enhanced by the pressure difference between the indoor air of the house and the soil (the “suction” effect). Thus, radon enters residential buildings mainly from underground sources through the soil, using cracks in rocks, utility gaps, and utility lines as conductors. The geological features of the Akchatau district (high radon content of rocks, active faults, high permeability of cover deposits) contribute to the intensification of this process, which confirms the need for constant monitoring and the implementation of radon protection measures during construction.
In 2023–2024, the studies were conducted seasonally: in winter, spring, and summer. All the measurements were performed in heated rooms with the temperature of 18–25 °C. The Alfarad Plus complex measures temperature, humidity, and pressure simultaneously with radon. When taking measurements using the algorithm built into the program, the measurement results are calculated and displayed on the device display. When measuring radon volumetric activity (VA) using the passive sampling method, the sensor is installed for 1–6 days at the shipping temperature. The air temperature during passive sampling on sorption columns SK-13 when measuring the average radon VA was from plus 12 °C to plus 30 °C, relative air humidity was up to 95% at the temperature of plus 30 °C, and atmospheric pressure was from 84 to 107 kPa. Humidity is taken into account during measurements by entering values in the appropriate column provided by the software. Humidity is determined by the weight method.
When studying the radioactivity of building materials, a gamma-spectrometric complex with a semiconductor detector made of high-purity germanium (HPGe) with a hardware complex manufactured by the NTC Aspect and the specialized SpectraLine software (version 3) was used. The energy resolution along the line is 1.33 keV–1.8 eV, and the relative registration efficiency is 21.8%. In accordance with the “Methodology of performing measurements”, the error is no more than 20% when using Marinelli vessels with a volume of 1 L. The studied samples of the 0–5 mm fraction are placed in a measuring container and placed in the spectrometer. The measurement time is 30–40 min. The detection limits of Ra226 and daughter decay products are at least 2 Bq/kg. The obtained results are assessed for compliance with the requirements of sanitary regulations, where the requirements for the specific effective activity of radionuclides in building materials are set at 370 Bq/kg.
The measurement of the equivalent equilibrium concentration (EEC) of radon isotopes in the air of the premises was carried out by a portable device and was considered an instantaneous measurement. EEC of daughter products of radon isotopes is a weighted sum of the activity values of short-lived daughter products of radon isotopes. The EEC of radon in the air was measured using equipment with an electrostatic chamber and is based on the fact that about 90% of the atoms of the daughter decay products have a positive charge.
The measurement time was 20–40 min. These are the Alfarad Plus devices manufactured in Moscow by New Technologies Group, Russia, as well as the Ramon-Radon radiometer manufactured in Almaty, Kazakhstan by Solo LTD. The Alfarad Plus device was equipped with a built-in microprocessor and the ALFA AR software, which provides automatic registration, processing, and storage of measurement results. This study allows the detection of the presence of a hazardous gas and the determination of its concentration, including the equilibrium coefficient between radon and its decay products. In subsequent data processing, the equilibrium coefficient was used to calculate the radon EEC based on the volumetric activity measurements of the quasi-integral detector. The measurement error was 20%.
The volumetric activity (VA) was determined by detectors placed in the room under study for 3–6 days. In this study, the “Chamber 01” equipment was used with activated charcoal; it is a passive radon detector developed and manufactured in the Republic of Kazakhstan. The method was based on passive sampling and sorption of a certain amount of radon depending on its volumetric activity. The measurement error was 20%.
First, radiometric measurements were carried out in the same rooms where radon concentration in the air was to be measured. The radon concentration was measured, if possible, in rooms that were not ventilated for at least 24 h. In each room, four measurements were taken, and the average value was taken.
In the Akchatau district, one- and two-story residential buildings with basements or ground floors predominate, often with insufficient waterproofing and natural ventilation. Such design features contribute to the penetration of radon from the soil into residential premises and its accumulation, especially in winter. The ambient dose equivalent rate was measured using DKS AT 1121 and DKS AT 1123 dosimeters. These are dosimeters with a scintillation detector that measures the ambient dose rate of continuous X-ray and gamma radiation in the range of 50 Sv/h to 10 Sv/h. The limit of the permissible basic relative error in measuring the dose and dose rate was ±15%. Measurements were carried out at a height of 1 m from the floor and no closer than 0.5 m from the walls in all rooms.
A feature of radon exposure is that its volumetric activity and the volumetric activity of the daughters can vary for one room by several orders of magnitude depending on the change in the air exchange rate. To take this effect into account, integrating radon detectors are used, i.e., detectors whose response is proportional to the average volumetric activity of radon over the measurement period. To obtain the AVA (average volumetric activity) over a measurement period of 1–6 days, detectors were used whose operating principle is based on the ability of activated charcoal to absorb radon from the surrounding atmosphere. The carbon adsorber method for determining the AVA is based on sampling with a sorption column with activated charcoal, open at one end, with subsequent measurement of the carbon activity by beta or gamma radiation of short-lived radon daughters Pb and Bi. Radon adsorption occurs passively, without the use of forced pumping.
In 2023, fifty detectors were placed at the school. When placing the detectors, no classes were held at the school (Minicenter 1). Only the security service was working.
During the winter season, 10 pairs of measurements of EEC-1 and AAVA-1 (average annual volumetric activity) of radon were performed. To analyze the relationship between the instantaneous values of EEC and AVA, a linear dependence was constructed. The trend line coefficient (Figure 3) was 0.282, which indicates a weak positive correlation between these indicators; the equilibrium coefficient between radon and its decay products is 0.4, which corresponds to typical values for non-ventilated rooms, and the coefficient of reduction in EEC radon during the daytime relative to the average during the day is 0.705, which is probably due to natural ventilation and decreasing the radon concentration during the daytime.
The graph shows the relationship between the activity measured over several days and the activity measured by the device for 30–40 min. The measurements were carried out mainly during the day, when the concentration is lower than at night. These results were used to calculate the average volumetric activity of radon and to assess the dose characteristics. Complex measurements of the volumetric activity of radon were carried out by specialists from Ecoexpert and Ecoservice-S.
The doses of radon exposure on the population are determined according to the Methodological Guidelines (order of the GSEN Committee, dated 09/08/2014, No. 94). The transition factor is adopted according to the Methodological Recommendations on Radiation Hygiene and is 5.1 × 10−9 Sv/(Bq × m−3 × h). There, the following is the accepted structure of human staying time: outdoors 0.2 annual time and indoors 0.8 annual time. Taking into account the insignificant share of radon inhalation outdoors, as well as the annual volume of inhaled air by an adult equal to 8100 m3/year (in accordance with Hygienic Standards No. KR DSM-71 02/08/2022 [40]), the algorithm for calculating doses from radon is as follows:
DRn = 0.8 × 8100 × 5.1 × 10−9 × EEC av. year.

3. Results

It is currently accepted that about 80% of the annual radiation dose of the planet’s population comes from radon and its decay products. Estimation of dose characteristics of radon hazard is a complex task due to the need to take into account many factors: the isotopic composition of radon and daughter products of their decay, the type and polyenergetic composition of ionizing measurements, the migration characteristics of dose-forming nuclides and their half-lives, the medical and biological aspects of radon radiation, etc. In our work, radon risk is estimated based on the effective annual radiation dose. Radiation safety standards must be calculated regardless of whether the radiation comes from natural or man-made sources of ionizing radiation. Therefore, systematic radon monitoring should not only be of independent importance but also be part of a complex of rehabilitation measures to survey areas exposed to man-made impacts.
The authors conducted seasonal studies that showed an increase in radon concentrations indoors from summer to winter.
The authors of [36] conducted a study of the building materials used in the village of Akchatau (Table 3). The table lists cinder blocks, foam blocks from the tailings dump, and bricks among the building materials in which the concentration of Ra226 is higher than 56 Bq/kg. For loose soils, the upper limit of the range of Ra226 activity is 40 Bq/kg, i.e., the radon flux density from the surface will not exceed the standard of 80 mBq/(m2 × s). From the analysis of Table 3, it is clear that most of the building materials studied have an excess of the reference levels of specific activity of Ra226. This indicates the potential radon hazard of such materials. The appearance of cracks in building structures additionally increases the release of radon into the air of the premises, which can lead to an increase in the volumetric activity of radon in residential buildings above the permissible levels.
It is possible that the radon activity level is largely affected by the nature of tectonics in the site and the time of construction (at a later time, less material from mining waste with increased radioactivity was used).
The gamma survey identified 11 anomalous areas and 12 point anomalies with exposure dose rate (EDR) values of more than 0.3 mSv/h with a background of 0.18 mSv/h. A large anomalous zone was identified in the northwest of the village with an excess of EDR of more than 0.6 mSv/h, which exceeds the average permissible value. The increased EDR values are caused by the presence of outcrops of leucocratic granites on the daylight surface located in the southeastern part of the village under study, as well as a closed mine and the presence of geological fault zones. Within this zone, there are one-story houses in four streets. It was in those houses that subsequent measurements revealed the highest concentrations of Rn222. In each surveyed house, measurements were taken at least three times at different times of the year, which made it possible to determine the average annual values of radon activity [41] and to construct maps of the distribution of halos of increased values of average annual EEC (Figure 4). A large number of measurements were carried out in the summer; the maximum EEC values were obtained during the study of the following streets: Baitursynov St. 350 Bq/m3, Torgovaya St. 516 Bq/m3, Aralbayev St. 1590 Bq/m3, and Shakhtyorskaya St. 458 Bq/m3. In spring and winter, radon concentration increases significantly. In spring, the values showed the following: Baitursynov Street: 1640 Bq/m3; Aralbayev St.: 2044 Bq/m3; Seifullin St.: 390 Bq/m3; Torgovaya St.: 827 Bq/m3; and Shakhtyorskaya St.: 713 Bq/m3. Several measurements were taken during the winter period: Aralbayev St.: 3291 Bq/m3; Seifullin St.: 1533 Bq/m3.
Based on Table 3 and Figure 4, it can be concluded that high radioactivity, in particular increased radon concentration, is also associated with building materials.
The highest indoor radon concentrations are noted in the northern part (especially in the area of Makhmetov Street), where the radon EEC in individual samples reaches 19,000 Bq/m3 and more. In this part, acidic granites come to the surface in geological terms, which could affect the increased radioactivity. At the same time, the values of the winter measurements are 2.07 times higher than the summer ones and 1.61 times higher than the spring ones. Based on this, it can be concluded that radon concentration increases from summer to winter. This can be due to the fact that in winter, the premises are insulated, which further complicates the release of radon from the premises. The increase in radon exhalation in summer is affected by daily fluctuations in soil temperature and the displacement of radon by soil moisture during precipitation. There are also many studies that confirm that the rate of radon emission depends on temperature and pressure and that there is a strong positive relationship between radon flux density and an increase in air temperature, as well as an inverse relationship with pressure changes [42,43,44,45].
In a comprehensive assessment of the radiation situation, the decisive role is played not by the activity of environmental radionuclides but by dose characteristics. Indeed, radionuclides with the same activity are capable of forming completely different effective doses both in the body as a whole and in its individual components.
The results of measuring the radon activity in the air of the premises under various ventilation conditions showed values from 13 Bq/m3 (with open windows and doors) to 11,821 Bq/m3 (when the premises are completely closed). According to the results of this study, one can talk about a significant decrease in the level of activity in the air of the premises as a result of their ventilation.
The results of the conducted studies indicate that most of the village belongs to the territory with an excess of average annual values of radon activity (EEC) and, accordingly, an excess of the radiation dose to the population.
High values of radon activity in the school premises (Minicenter 1, up to 2000 Bq/m3 and more) are noteworthy, detected mainly on the ground floor of the school building. Based on the results of this study and previously conducted work, it can be concluded that the maximum radon activity is observed in the premises of the first floor and basement, where there is no air movement. In addition, the radon concentration in the premises decreases with height. In the director’s office, the sensors were installed at different heights (on the floor, activity was 1770 Bq/m3; at a height of 30 cm, 1670 Bq/m3; at a height of 75 cm, 990 Bq/m3; and at a height of 190 cm, 450 Bq/m3). According to the results of the studies, no excess concentrations were found in the rooms on the first floor. A high concentration of radon is noted in the basement, which indicates that the main supplier of radon is the soil under the building. In the northwestern part of the territory, acidic granite outcrops are also observed on the surface, which confirms the increased concentrations on the lower floors and basements.
At the same time, in some buildings, single measurements were made, where the reference level of 200 Bq/m3 was exceeded in 23% of the surveyed premises.
Based on the results of calculating the average annual radon EEC, a frequency analysis was performed for 181 premises (Figure 5), which shows that for 43.1% of premises, the effective dose from radon EEC varies from 6.6 mSv/year to 33 mSv/year, and for 9.4% of premises, the effective dose from radon EEC varies from 33 mSv/year to 680 mSv/year. For 47.5% of premises, they comply with the current standards, in which the average annual radon EEC does not exceed 200 Bq/m3.
The obtained results indicate the need to apply anti-radon measures in the studied premises, as well as the use of supply (or positive) ventilation to increase the pressure in the room in relation to the basement (space under the floor). The street is organized in the usual way in relation to each room of the first floor and first-floor exhausts in the space under the floor. Special requirements for the organization of the ventilation system in terms of radon hazard are not required. The main requirement is to create an excess of pressure relative to the basement and the street, which in turn will ensure the dilution of radon after its entry.

4. Conclusions

The main anthropogenic source of radon hazard in the studied Akchatau district is a hydrothermal tungsten–molybdenum deposit located near rare-metal–uranium–thorium structural–metallogenic zones. In the context of radiation safety, radon radionuclides create approximately 75% of the annual equivalent dose for the population. Moreover, significant radiation hazards are created by radionuclides Rn222, Rn220, and their daughter products (radioisotopes Po, Pb, and Bi). The frequency analysis of radon EEC in 181 premises of the village of Akchatau in the Karaganda region showed that only in 47.5% of the surveyed premises does the average annual effective dose not exceed 200 Bq/m3, and in 43.1% of the premises the effective dose varies from 6.6 mSv/year to 33 mSv/year.
The main factors causing high radon concentrations in the houses of the village are high exhalation from the soil surface, the radioactivity of building materials, and low air exchange in the premises.
Significant seasonal changes in radon volume activity have been established. The measured values of radon activity in winter periods are approximately 2.1 times higher than summer measurements. In the northwestern part of Akchatau, anomalous zones have been identified where the exposure dose rate of gamma radiation exceeds 0.6 mSv/hour with the background value of 0.18 mSv/hour. The use of comprehensive measures to reduce radon volume activity is relevant for 37% of the surveyed premises. Systematic measures are needed to minimize the flow of radon into the premises and to remove it as much as possible using active and passive methods.
The importance of the radon radiation problem in Kazakhstan requires the practical implementation of large-scale programs to assess and to reduce the level of public exposure from natural radioactive sources and ionizing radiation. Guided by the recommendations of the ICRP, it is necessary to continue a more detailed study of architectural, construction, and engineering characteristics, which, in interaction with environmental factors, will allow developing effective strategies for reducing radon levels. The existing methods of reducing radon radiation levels cannot claim to be viable in the long term. Regarding systematic radiation, environmental and hygienic monitoring of radon safety levels in the environment are needed to reduce effective doses in the population.

Author Contributions

Conceptualization: Y.P.; preparation of the initial draft: D.P. and V.M.; methodology: D.I. and P.T.; formal analysis: A.T. and P.M.; software: D.P. and Y.B.; writing, reviewing, and editing: D.I., Y.P. and P.T.; project administration: Y.P. and V.M. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the Science Committee of the Ministry of Science and Higher Education of the Republic of Kazakhstan (grant no. AP19678770).

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

The original contributions presented in this study are included in the article. Further inquiries can be directed to the corresponding author.

Acknowledgments

The authors express their gratitude to the employees of Ecoexpert LLC, Ecoservice-S, and the Institute of Nuclear Physics.

Conflicts of Interest

Vladimir Matonin, Pavel Timoshenko, Yuriy Barkov, and Pavel Medvedev are employees of Ecoexpert LLP. The paper reflects the views of the scientists and not the company. The authors declare no conflict of interest.

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Figure 1. Scheme of zoning the territory of Kazakhstan according to radon hazard.
Figure 1. Scheme of zoning the territory of Kazakhstan according to radon hazard.
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Figure 2. Schematic geological map of the Akchatau granite massif (compiled by Beskin S.M., Larin V.N., Marin Yu.B., and Rubo G.L.). 1—loose Quaternary accumulations; 2–10—Akchatau complex (P): 2—wolframite–quartz veins with greisen rims; 3–6—vein greisens (3—dense quartz, W; 4—quartz–topaz, a, and topaz–quartz, b; 5—quartz–muscovite, W and others; 6—quartz with “beresite” rims, Mo); fine-grained aplite-like alaskites, vein (7); fine-grained miarolitic alaskites, vein (8); medium-fine-grained alaskites B-4 (9) and medium-grained alaskites B-3 (10). 11–13—Kaldyrma complex (C3): fine-grained, often porphyritic granites; veined and undifferentiated (11); medium-fine-grained sharply porphyritic biotite granites A-4 (12); and medium-grained porphyritic granites A-2 and A-3 (13). 14—Topar complex (C2): granodiorites and adamellites; 15—sandstones, tuffs of quartz porphyry, and andesite porphyrites and their tuffs (Karkaraly suite); 16—sandstones, siltstones, and shales (Ludlov); 17—tectonic faults; 18—contacts traced (a) and approximate (b); 19—the bedding of contact surfaces is gentle up to 300 (a), and steep (b); and 20—section lines.
Figure 2. Schematic geological map of the Akchatau granite massif (compiled by Beskin S.M., Larin V.N., Marin Yu.B., and Rubo G.L.). 1—loose Quaternary accumulations; 2–10—Akchatau complex (P): 2—wolframite–quartz veins with greisen rims; 3–6—vein greisens (3—dense quartz, W; 4—quartz–topaz, a, and topaz–quartz, b; 5—quartz–muscovite, W and others; 6—quartz with “beresite” rims, Mo); fine-grained aplite-like alaskites, vein (7); fine-grained miarolitic alaskites, vein (8); medium-fine-grained alaskites B-4 (9) and medium-grained alaskites B-3 (10). 11–13—Kaldyrma complex (C3): fine-grained, often porphyritic granites; veined and undifferentiated (11); medium-fine-grained sharply porphyritic biotite granites A-4 (12); and medium-grained porphyritic granites A-2 and A-3 (13). 14—Topar complex (C2): granodiorites and adamellites; 15—sandstones, tuffs of quartz porphyry, and andesite porphyrites and their tuffs (Karkaraly suite); 16—sandstones, siltstones, and shales (Ludlov); 17—tectonic faults; 18—contacts traced (a) and approximate (b); 19—the bedding of contact surfaces is gentle up to 300 (a), and steep (b); and 20—section lines.
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Figure 3. Comparison of the radon winter values of AAVA-1 and EEVA-1.
Figure 3. Comparison of the radon winter values of AAVA-1 and EEVA-1.
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Figure 4. Map of the average annual radon EES values.
Figure 4. Map of the average annual radon EES values.
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Figure 5. Frequency analysis of average annual EES.
Figure 5. Frequency analysis of average annual EES.
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Table 1. Radon sources in the atmosphere [2].
Table 1. Radon sources in the atmosphere [2].
SourceRn Generation per Year, Bq
Soil9 × 1018
Plants and groundwater<2 × 1018
Oceans8.5 × 1017
Houses3 × 1016
Natural gas3 × 1014
Coal2 × 1013
On average1.2 × 1018
Table 2. Geological factors of the Akchatau district [38,39].
Table 2. Geological factors of the Akchatau district [38,39].
No.Geological FactorManifestation in the Akchatau DistrictEffect on the Radon Level
1Type of rocksGranitoids, pegmatites, uranium-bearing intrusionsHigh uranium content, active radon formation
2Permeability of cover depositsSandy loams, sands, loess depositsFacilitate vertical migration of radon
3Depth of radioactive rocksSometimes less than 10–15 mIncreases the likelihood of radon reaching the surface
4Faults and fracturingDeep faults, up to 5–7 km, intersect the residential areaCreate channels for radon from the depths to the surface layers
5Hydrogeological conditionsSeasonal drying of rocks, variability of groundwater levelsAt low humidity, radon release increases
Table 3. Radon activity of building materials [36].
Table 3. Radon activity of building materials [36].
No.MaterialNumber of HousesRadon Average Activity, Bq/m3
Southwestern part of the village
1Cinder block, Foam block53246.48
2Concrete, Monolith16146.54
3Brick9426.55
Northeastern part of the village
1Cinder block, Foam block12348.25
2Concrete, Monolith3167
3Brick, Stone25330.08
Northern part of the village
1Cinder block, Foam block144641.93
2Concrete, Monolith172
3Brick, Stone61668.83
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Pak, Y.; Pak, D.; Matonin, V.; Ibragimova, D.; Timoshenko, P.; Barkov, Y.; Tebayeva, A.; Medvedev, P. Study of Radon Radiation in the Area of the Akchatau Polymetallic Mine, Republic of Kazakhstan. Atmosphere 2025, 16, 769. https://doi.org/10.3390/atmos16070769

AMA Style

Pak Y, Pak D, Matonin V, Ibragimova D, Timoshenko P, Barkov Y, Tebayeva A, Medvedev P. Study of Radon Radiation in the Area of the Akchatau Polymetallic Mine, Republic of Kazakhstan. Atmosphere. 2025; 16(7):769. https://doi.org/10.3390/atmos16070769

Chicago/Turabian Style

Pak, Yuriy, Dmitriy Pak, Vladimir Matonin, Diana Ibragimova, Pavel Timoshenko, Yuriy Barkov, Anar Tebayeva, and Pavel Medvedev. 2025. "Study of Radon Radiation in the Area of the Akchatau Polymetallic Mine, Republic of Kazakhstan" Atmosphere 16, no. 7: 769. https://doi.org/10.3390/atmos16070769

APA Style

Pak, Y., Pak, D., Matonin, V., Ibragimova, D., Timoshenko, P., Barkov, Y., Tebayeva, A., & Medvedev, P. (2025). Study of Radon Radiation in the Area of the Akchatau Polymetallic Mine, Republic of Kazakhstan. Atmosphere, 16(7), 769. https://doi.org/10.3390/atmos16070769

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