Determination of Residential Soil Gas Radon Risk Indices Over the Lithological Units of a Southwestern Nigeria University (original) (raw)
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International journal of public health research, 2016
The radon concentration and natural radioactivity i n soil of Aramoko, Ekiti State, Nigeria have been d etermined. The soil gas radon measurement was performed in-situ with Rad7 r adon monitor coupled with a soil gas probe. Natural radioactivity measurement in soil samples was carried out using N aI(Tl) gamma spectrometer. This study is aimed at d etermining the correlation between the radioactivity of the soil a nd its radon concentration. It was found that the r adon concentration of soil gas in the study area ranged from 0.63BqL -1 to 35.04BqL -1 with an average value of 9.82±0.56BqL -1 . The average activity concentrations of 238 U, 232 Th and 40 K were found to be 22.62Bq/Kg, 34.74Bq/Kg and 316.7 2Bq/Kg, respectively. The average radium equivalent and average absorbed dose rates a t a height of 1m above the ground are 95.99±62 BqKg -1 and 45.18±27.28 nGyh -1 respectively. The mean external and internal hazar d indices were also found to be 0.26 and 0.32 respe ctively. All the d...
Journal of Environmental and Public Health
Seasonal radon levels have been studied in dwellings and soils in selected areas in Ga East, Greater Accra Region of Ghana using LR-115-type II (SSNTDs). This study was conducted to determine the seasonal correlation between soil and dwelling radon concentrations. Detectors were exposed from January to March and April to June, for dry and wet seasons, respectively. Overall, indoor radon was 133.4 ± 6.7 Bqm−3 and 72.1 ± 3.6 Bqm −3 for wet and dry seasons. The estimated annual effective dose to the lung received by the occupants at Paraku Estate, Dome, and Kwabenya was 6.9 ± 0.4, 7.2 ± 0.5, and 9.8 ± 0.8 mSvy−1 for the wet season and 3.8 ± 0.2, 4.3 ± 0.2, and 4.6 ± 0.3 mSvy−1 for the dry season. On average, the soil radon concentration was found to be 0.96 ± 0.07 kBqm−3 and 2.24 ± 0.01 kBqm−3 for wet and dry seasons. To determine the correlation between soil and dwelling radon, a positive Pearson correlation coefficient value R = (0.74) and R = (0.66) was obtained representing the dry...
Nigerian Journal of Physics (NJP), 2024
The evaluation of radon concentration in soil sample from boreholes in Kaltungo local Government area of Gombe state, Nigeria have been carried out. A total of fifteen (15) soil samples were collected from different boreholes sites in five (5) different locations and were analyzed using Gamma spectrometry (Sodium Iodide with thallium NaI (TL) detector. The mean result of Radon activity concentration obtained varies from 0.86± 0.05 to 1.71± 0.03 Bqm-3 and the annual effective dose rate ranged from 0.0039 to 0.0077WLm/y respectively. The result shows variations in the radon concentration with various depths which indicates a relative dependence of radon concentration with depths. Comparing the results with the WHO recommended value of 100 Bqm-3 indicate that the mean values for all the boreholes soil samples were below the world recommended value. Also the mean values for all the boreholes soil samples were below the world average radon concentration of 40Bqm-3 (UNSCEAR). The values of AEDE obtained in various borehole soil samples were less than the ICRP world average. Therefore, the soil samples in each of the borehole may not pose any health threat to the residents.
Research Square (Research Square), 2022
In the U series, Rn − 222 (T 1/2 = 3.82 days) builds up more quickly in homes. Although it originates from rocks and dirt, it dissolves in water. A RAD7 solid state detector was used to test the outdoor and soil gas in-situ radon-222 activity at 26 locations in Abeokuta, Nigeria. The six geological formations that were picked for a cell and spaced at least 3 km apart served as the basis for choosing the measuring site. The Global Positioning System compass was used to determine the locations of the measurement sites. Outdoor radon levels ranged from (0.001 to 4530) Bqm − 3 while soil gas levels ranged from (52.5 to 19250) Bqm − 3. In comparison to the reference level for outdoor radon recommended by the International Commission on Radiological Protection (ICRP), which ranges from (100 to 300) Bqm − 3 , the average outdoor radon concentration value measured was 463.52 Bqm − 3. The exhalation rate ranged from (0.000108 to 0.0395) Bqm − 2 s, and the rate of production of soil gas activity ranged from (0.00011 to 0.0404) Bqm − 3 s. The mean annual effective dose from outdoor radon activity was determined to be 4.242 mSv/year, which is greater than the ICRP-recommended limit of 1 mSv/year for dosage from public exposure. The annual effective doses ranged from 0 to 16.57 mSv/year. The measured values did not correlate, which may be partially explained by the characteristics of the soil and by meteorological conditions.
FUDMA Journal of Sciences , 2020
Radon and its short-lived progenies contributed significantly to natural background radiation. Long-term exposure to such radiation increases the probability of lung cancer to persons. To assess the radiological hazards associated with the inhalation of radon gas from ore dust in Mazat and Kafi-Habu mining sites of Plateau, Nigeria, 12 soil samples from an abandoned tailing dump ground were collected and analysed for radon using RAD-7 electronic detector. The dose rate of each sampling point was directly measured using RADOS RDS-120 portable survey meter. The results gave a mean radon concentration ranging from 771.51 ± 21.9 Bq/m 3 to 5666.13 ± 28.8 Bq/m 3 with 3451.13 ± 42.9 Bq/m 3 as the average value for all measurements. The average concentration of measurements from Mazat and Kafi-Habu is 3671.6 ± 41.2 Bq/m 3 and 3010.16 ± 46.5 Bq/m 3 respectively. The average values obtained from the analysis are significantly higher than the upper limit of 300 Bq/m 3 set by the International Commission on Radiological Protection (ICRP) suggesting quick remediation on the host communities. The geometrical mean value of Dose Rate (DR) and Annual Effective Dose Equivalent (AEDE) were 870 nGy/hr and 1.04 mSv/yr respectively. Again, these values are above the global average limits of 59 nGy/hr and 1 mSv/yr. The result indicates that miners working in those sites and dwellers of the study areas are at higher risk of getting exposed to radon and need to employ protective measures. This work is useful in monitoring and control of radon level for the on-site workers and the host communities.
Journal of Geophysical Research: Atmospheres, 2024
The objectives of the current study are to carry out soil gas radon (Rn) measurements, to evaluate the total inhalation effective dose, to determine risk levels over the lithological formations of the study area. The behavior investigation of Rn activity concentration distributions in dwellings and soils, and soil Rn mapping were also conducted. Soil gas Rn measurements were made at 102 sampling points by Markus 10 instrument. This data was combined with previously reported results from 140 indoor Rn RADTRAK dosimeters to determine the total inhalation effective dose and to conduct a statistical analysis. Overall, the Rn activity concentrations in soil and dwellings range from 4 to 66 kBq m 3 and from 15 to 140 Bq m 3 , with averages of 31 ± 15 kBq m 3 and 41 ± 24 Bq m 3 respectively. The corresponding total inhalation effective dose ranges from 0.35 to 3.53 mSv y 1 , with a mean value of 1.37 ± 0.58 mSv y 1. For soil gas Rn, the chlorite schist lithology showed the highest average concentration level. Which could be justified by the possible presence, within chlorite minerals, highly emitting zones of alpha particles, leading to the formation of radioactive halos. Normal and high-risk level of Rn were found for about 82% and 11% of the total area surveyed respectively. These findings highlight the need for preventive measure against Rn exposure in homes within the investigated areas. This study contributes valuable insights into Rn distribution patterns and risk assessment, offering a basis for targeted interventions in the region. Plain Language Summary Radon (222 Rn (Rn or radon)) is the ubiquitous natural radioactive gas in the earth's crust. It is responsible for about 50% of the total dose received by the public from exposure to natural ionizing radiation. This gas have been recognized as the second leading cause of lung cancer in the world. The current work objectives are to measure the soil gas Rn activity concentrations, to assess the total inhalation dose received by the public and to determine risk levels of various lithological formations. In general, we found that the chlorite schist lithology had the highest average concentration level, due to the presence of minerals such as biotite and chlorite. Public exposure to Rn is greater indoors than outdoors with average inhalation dose relatively higher than the worldwide average. This is due to the numerous factors such as type of construction, building materials, low indoor air renewal rates, etc. The whole study area surveyed were classified as normalrisk zones. These results reveal that preventive and protective measures against the public exposure to Rn are required from the construction of dwellings. Based on the activity concentrations distribution model and risk assessment, areas that could be targeted for potential intervention could be identified. 2. Materials and Methods 2.1. Physical and Geological Setting of the Study Area The study area covers the localities of Yaoundé, Okola, Monatele, Obala, and Mbalmayo in the Center Region of Cameroon, spanning, latitudes 3°10′00″ to 4°30′00″N and longitudes 11°10′00″ to 12°0′00″E. This region belongs to the classic sub-equatorial Guinean climate which is characterized by alternating (regular succession) of
Radon soil–gas as a geological mapping tool: case study from basement complex of Nigeria
Environmental Earth Sciences, 2005
In an effort to quantify the geogenic radon soil–gas potential and appraise the use of radon technique as a geological mapping tool in a crystalline basement rock terrain of Ile–Ife Nigeria, radon measurement concentration were made using a radon detector instrument (EDA RD-200) that measures radon isotopes by a scintillator cell coupled to a photomultiplier tube. The data were collected from soils derived from three different lithologic rock units. The observed values were then correlated with the geology of the area. Significant differences in the radon soil–gas concentrations among the three geologic units were observed. Granite gneiss has the highest concentration, followed by grey gneiss and mica schist in that order. The geometric mean (GM) concentration of radon-222 measured in soils directly overlying the three different rock types were 301.4 pCi/l for granite gneiss, 202.8 pCi/l for the grey gneiss, and 199.4 pCi/l for mica schist. Conversely, the average values for radon-220 averaged 1510.0, 815.4, and 733.0 pCi/l for granite gneiss, grey gneiss, and mica schist rocks, respectively. Statistical t test (α=0.05) results indicated that there was no significant difference in the geometric mean of radon soil–gas measured between low and medium potential zones. However, significant differences were found between the low and high radon potential zones, and between the medium and high zones. The low concentrations of radon soil–gas emission observed in this study is explained in terms of the seasonal variation due to thermal convection fluid movement, while the radon concentrations were found to be controlled by the lithology and geochemistry of the underlying bedrock.
Physical Science International Journal
This study evaluates the radon concentrations in public places and private residences with different altitudes in selected locations in Delta State. These measurements were carried out using a professional radon monitoring instrument (Alpha GUARD PQ2000 PRO) and a geographical positioning system (GPS-Garmin GPS Map 76S). The recorded mean radon concentration varied from 11.70 ± 5.20 Bq/m3 to 23.90 ±16.60 Bq/m3, which is within the WHO acceptable range (100 Bq/m3). The basement had greater radon concentrations than the upper floors in most situations, although there were few exceptions. The average values of the estimated radiation risk parameters, which include equilibrium equivalent radon concentration, the potential alpha energy concentration, radon exhalation rates, and excess lifetime cancer risk due to exposure to radon radiation from their progeny are 4.7 Bq/m3 to 9.5Bq/m3, 1.20 × 10-3mWL to 2.60 × 10-3mWL, 0.04 × 10-3WML/y to 0.09× 10-3 WML/y, 3.7Bq/m2/h to 7.52Bq/m2/h and 2...
Risk assessment of radon in the South Dayi District of the Volta Region, Ghana
Journal of Radiation Research and Applied Sciences
Radon is a globally present and known radioactive gas with its ability to cause lung cancer as its major health implication. Ghana currently lacks national policies on radon gas and substantive radon vulnerability map largely due to lack of adequate baseline radon concentration data for the entire country. LR115 type II detectors were deployed in 30 sites/homes within the South-Dayi District. The detectors were retrieved after specified periods and analyzed for the radon concentration at the Nuclear Track Detection Laboratory of the Ghana Atomic Energy Commission. From the results, indoor radon concentration was found to range from 11.60 to 111.07 Bq/m 3 with the mean value for the district being 34.90 ± 20.18 Bq/m 3 , a value lower than the mean global indoor concentration of 40 Bq/m 3. The values of 0.44 mS/yr, 8.80 mSv/yr and 1.01 mSv/yr were the mean annual; absorbed dose, equivalent dose and effective dose to lungs respectively for the populace of the district. The mean soil radon concentration for the district was 1.76 ± 0.91 kBq/m 3 with values ranging from 0.38 to 3.93 kBq/m 3. Correlation and T-test analysis was performed to establish strength of the linear relationship between indoor radon concentration and the soil radon concentration, indoor radon concentration on altitude and soil radon concentration on altitude.
Journal of Environmental Health Science and Engineering, 2020
Purpose In this study, measurements of radon concentrations and estimation of exhalation rates were carried out in soil around buildings within Lagos State in order to determine the contribution to indoor radon concentrations from the soil, and determine the influence of soil moisture on the exhalation rates. Methods Fifty-four samples were collected randomly with 27 measured as wet samples and 27 dried before measurements so as to account for the moisture content. Passive measurement method, using cover cup technique with solid state nuclear track detectors, CR-39, was employed. Results The results showed weak correlations between the concentrations of radon emanated from the soil samples and the indoor radon concentrations. The results obtained suggested lower concentrations of radon emanated from wet soil than dry soil indicating the influence of moisture. The results further indicate that the highest and lowest values as well as the highest mean for both wet and dry soil samples were obtained from the same environment, suggesting that the soil in that environment are of anomalous petrophysical property. Conclusion Concentrations of radon emanated from dry soil are higher than in wet soil, suggesting that the presence of moisture may results in reduction of radon concentrations in soil samples. The result of the surface exhalation rates and the mass exhalation rates are in congruent with results obtained for the concentrations of radon emanated from wet and dry soil samples.