Heliyon 9 (2023) e15259
Contents lists available at ScienceDirect 
Heliyon 
journal homepage: www.cell.com/heliyon 
Research article 
Radon mapping, correlation study of radium, seasonal indoor 
radon and radon exhalation levels in communities around Ghana 
atomic energy commission 
Francis Otoo a,b,*, Rita Kpordzro a,b, A.S.K. Amable c 
a Radiation Protection Institute, Ghana Atomic Energy Commission, P. O. Box LG 80, Legon-Accra, Ghana 
b School Nuclear and Allied Sciences, University of Ghana, Atomic Campus, P. O. Box AE1, Legon-Accra, Ghana 
c School of Basic and Biomedical Sciences, Department of Basic Sciences, University of Health and Allied Sciences, PMB 31, Ho - Volta, Ghana   
A R T I C L E  I N F O   A B S T R A C T   
Keywords: Radon mapping and seasonal radon studies have been carried out within the communities around 
Radon concentration the Ghana Atomic Energy Commission (GAEC), using ArcMap geostatistical interpolation tool. 
Dwellings The correlation analysis was done using Pearson’s correlation tools. Average seasonal indoor 
Soils radon variations for CR (rainy) and CD (dry) with mean values ranging from 28.9 to 177.2 Bq/m3 CR-39 
HPGe (78.1 ± 38.7 Bq/m
3) and 24.4–125.5 Bq/m3 (69.9 ± 24.2 Bq/m3). Average seasonal soil radon 
exhalation for ER (rainy) and ED (dry) with mean values ranging from 39.6 to 100.3 (68.9 ± 24.2 
μBq/m2 h) and 55.2 to 111.9 (77.1 ± 18.7 μBq/m2 h). Radium concentrations ranged from 8.1 to 
42.2 Bq/kg (21.3 ± 9.9 Bq/kg). Annual effective dose and resultant effective dose to lungs were 
found to be 0.9 to 2.9 (1.9 ± 0.8 mSv/yr), 2.1 to 9.2 (4.6 mSv/yr). The study recorded the highest 
and lowest positive correlation coefficient was found in the study with higher and lower coeffi-
cient values of 0.81 and 0.47 recorded in radium concentration with radon exhalation and indoor 
radon concentration within the dry season respectively. Pearson correlation result recorded 
values 0.81 and 0.47 as the highest and lowest positive coefficient values for the radium con-
centration correlation between radon exhalation and indoor radon concentration. One directional 
principal component was observed in radium concentration, seasonal radon exhalation, and in-
door radon concentration. Two clusters originated from radium and seasonal radon concentra-
tions present in dwellings as well as soils. Pearson’s correlation results were in agreed with the 
principal component and cluster factor analysis. The study obtained the highest and lowest indoor 
radon concentrations with radon exhalation in rainy and dry seasons. Radium concentration was 
found to have a considerable effect on indoor radon and radon exhalation in dwellings and soils.   
1. Introduction 
Radon exists everywhere from workplaces to dwellings as well as soils. Most of the radiation exposure to the public was found to be 
radon gas, especially in an indoor environment [1–4]. Radon and its progenies get to the body by inhalation. Continuing exposure to 
elevated radon gas for long periods in enclosed areas has been linked to a higher risk of lung cancer in exposed individuals. Indoor 
radon exposure is categorised as the most cause of lung cancer cases second to smoking tobacco. About 5% to 20% of lung cancer 
* Corresponding author. Radiation Protection Institute, Ghana Atomic Energy Commission, P. O. Box LG 80, Legon-Accra, Ghana. 
E-mail address: kwaotoo@yahoo.com (F. Otoo).  
https://doi.org/10.1016/j.heliyon.2023.e15259 
Received 23 January 2023; Received in revised form 30 March 2023; Accepted 31 March 2023   
Available online 6 April 2023
2405-8440/© 2023 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license
(http://creativecommons.org/licenses/by/4.0/).
F. Otoo et al.                                                                                                                                                                                                  H   e l i y  o  n 9 (2023) e15259
deaths may attribute to radon exposure [2,4]. Radon resulted from the direct progeny of Radium-226 as a decay product of 
uranium-238 decay series in building materials, rocks, and soil. The amount of radon gas that retains or emanates into the air from soil 
or rocks in the buildings depends on the dwelling construction type, occupant behavior, building materials, water supplies, radium 
concentration differences in soil, and rock geology underlying the dwellings [5–8]. Higher lung cancer cases were found to be coming 
from uranium miners and prolonged indoor radon gas exposure to the public [9,10]. This incident led to an engendering interest in 
indoor radon and radon exhalation studies in dwellings and soils [9,10]. 
To determine radon concentration in dwellings and soils, there have been several studies and procedures to assess the risk of radon 
exposure and identify radon-prone areas [11–15]. The most common techniques mostly used are geostatistical which involve vario-
gram fit and kriging [12–15]. These methods were used to study radon levels and for developing potential radon maps. This procedure 
can also use to study radon distribution patterns as well as the classification of radon-prone areas [11–15]. 
Studies report on the radon levels and their distribution in soil and dwellings vary from season to season, type of buildings, and 
location to location [16–22]. Seasonal indoor radon was found to be affected by the meteorological parameters, geology, radium 
concentration, construction materials, and building type, as well as the ventilation rate in closed environments [5,22–26]. The indoor 
radon variation concentration in a given dwelling could be affected by environmental factors. Radon studies indicated that seasonal 
variational factors were found to be varied with radon levels in soils and dwellings. The winter or rainy season has higher radon 
concentration mostly occurring in winter or rainy periods than other seasons [16–29]. This is because windows and doors tend to be 
shut for a period longer than in the dry season leading to an increase in radon levels as a result of the lower ventilation rate [30]. 
Seasonal radon variation in dwellings and soils was found to be a very important phenomenon and its impacts on the dependence of 
radium concentration due to radon exposure to the public. Some studies conducted on soils, and building materials indicate radium 
concentration is a potential source of increasing indoor radon concentration in dwellings [5,16,31]. 
Some radon studies have been done in other countries to establish the radium concentration dependence on radon gas in soils and 
dwellings, this is in order to determine radon-prone areas or radon indoor levels [15,16,30]. Studies of seasonal indoor radon with 
radium concentration and associated effective doses are very important from a radiation protection perspective. This is to help in 
reducing the likelihood of a higher incidence of lung cancer associated with prolonged exposure to higher radon levels in dwellings [2, 
4,17,32]. In Ghana, the majority of radon and radium studies have focused on radon exhalation rates in soils, rocks, and building 
materials [5,27,32,33]. Some studies have reported on seasonal variations of radon between dwellings and soils [16,17,20], but there 
is no comparable study that establishes a radon map and the determined effects of radium concentration on seasonal indoor radon and 
radon exhalation in soils and dwellings. Therefore, this study assesses radon mapping, seasonal indoor radon indoor, seasonal radon 
exhalation, and its dependence on radium concentration. This is to ascertain the influence of radium concentration on radon levels and 
associated effective doses to residents around the Ghana Atomic Energy Commission (GAEC). 
Fig. 1. Geological map of the study areas.  
2
F. Otoo et al.                                                                                                                                                                                                  H   e l i y  o  n 9 (2023) e15259
2. Materials and methods 
2.1. Geology of the study area 
The location of study around GAEC. It is tropical and characterized by slight temperature differences throughout the year with 
average temperature varying from 24.7 ◦C to 28.0 ◦C. The highest and lowest temperature was found to occur in August and March. 
The average annual temperature within the study areas is 26.8 ◦C. This study area sits below 1000 m (3300 ft) with daylight being the 
same throughout the year, as a result of being nearer to the equator along the coast with higher relative humidity. 
Soil within the study location comprise four main different types such as: drift materials deposits by windblown erosion; alluvial 
and marine motted clays below shales; residual clays and gravels come from weathered quartzites, gneiss, and schist rocks while 
lateritic sandy clay soils obtained from weathered Accraian as a result of the sandstone bedrock structures. Black cotton soils of pockets 
from the alluvial origin are normally obtained in a weak drained area. The area has a soil enclosed with heavy organic levels, can 
expand, and contract easily causing breaks in foundations and footings of the buildings. Strongly acidic associated with the study 
location, weaken the concrete foundation resulting in honeycombing when saturated. Alluvial laterite gravels and sands mainly come 
from the foothills [34,35]. 
2.2. Building materials and occupancy 
Typical building construction associated with these studied dwellings are used depending on the location, type of building, and 
cost. Building wall uses cement, sandcrete and concrete blocks for the walls. Wooden structures are not frequently used as a building 
material compared to blocks, even though it is exported from Ghana, Metal sheets, slate, or asbestos are commonly used for roofing. 
Materials used for floor consist of concrete or cement, terrazzo, tiles, and ceramic [5,36]. The dwellings consist of a storey, bungalows, 
compound houses, etc. With the single room having 2–10 occupants. 
2.3. Sample collection and preparation 
A total of 36 soils from 18 locations within communities around the Ghana Atomic Energy Commission were taken from the lo-
cations in Fig. 1. Soils were taken randomly depending on suitability, accessibility, and availability. The soil samples were taken from 2 
or 3 different places within the study. Sampled soils were put into labeled different Ziploc bags tightly closed and sent to the radon 
laboratory of the Radiation Protection Institute, Ghana Atomic Energy Commission (RPI/GAEC). 
The sampling equipment was carefully cleaned after each sampling point with a different neat rag to prevent any water droplets and 
soil particles to prevent cross-contamination. Analyses of radium and radon concentration were done at the RPI/GAEC. Soil collected 
was standardized, air-dried, and sieved to a particulate uniform mixture size of 2 mm, and sealed in 500 mL beakers. The weight of the 
beakers and samples was recorded. Prepared samples were kept at room temperature for 4 weeks to permit the radioactive equilibrium 
between the parent of 38U and 226Ra decay series with short-lived daughter product [32,37]. 
2.4. Determination of activity concentration of radium 
2.4.1. Calibration of HPGe 
HPGe detector calibration was done by evaluating the efficiency of the sensor using a multigamma-ray solid varied from 46.5 keV to 
1836.1 keV with 1 g/cm3 density in the same geometry used for the analysis of the samples [38]. The detector was shielded with a lead 
of 100 mm lined with copper, cadmium, and plexiglass sheets. Calibration was done using the standard source with the following 
specific activities; 210Pb, 6.63 × 105 Bq; 241Am, 6.60 × 104 Bq; 109Cd, 4.39 × 105 Bq; 57Co, 1.23 × 104 Bq; 123 Te m, 7.65 × 103 Bq; 
113Sn, 2.72 × 104 Bq; 85Sr, 1.05 × 104 Bq; 137Cs, 9.81 × 104 Bq; 88Y, 4.63 × 104 Bq, 60Co, 1.16 × 105 Bq. GESPECOR software was used 
for the self-absorption corrections for the measurement of soils with higher density [39]. 
2.4.2. Estimation of activity concentration of radium content 
The radium concentration was estimated using the energy lines of the decay product. The average energy peak for 226Ra was 
evaluated using the following lines: 214Bi, (609.31, 1120.29, 1764.49 keV) and 214Pb (295.22, 351.93 keV). Soil samples with more 
than one peaks for progenies. Their average energy lines were used to estimate the activity concentration of 226Ra. An empty Marinelli 
beaker of geometric features similar to the counted soil samples with HPGe, was used to determine the background concentration. The 
226Ra in the soils were analyzed for 72,000 s. Spectroscopy Genie 2000 V3.3 (1) software from Canberra was used for display, 
acquisition, and on-line spectrum analysis [32,37]. The 226Ra concentration was determined using equation (1), 
(N − N )
Ac(226 Sam BRa)= (1)  P(E) ∗ n(E) ∗ Tc ∗ Msam
where Ac activity concentration of radium (Bq/kg); Msam mass of the soil sample(kg); Nsam net count of sample (cps), NB count rate for 
the background (cps); Ƞ(E) represents the photo peak efficiency from the standard solution; P(E) gamma emission probability, and 
Tc(s) counting time in seconds. 
3
F. Otoo et al.                                                                                                                                                                                                  H   e l i y  o  n 9 (2023) e15259
2.4.3. Radon measurement 
2.4.3.1. Indoor radon. Radosys set up with CR-39 detectors enclosed in RSKS type diffusion chambers were used for this study. The 
calibration factors of the CR-39 are supplied and traceable to the radon calibration laboratory of the Federal Office for Radiation 
Protection in Germany [40,41]. This study uses one hundred and twenty eight (128) CR-39 passive radon detectors in bedrooms and 
sitting rooms in 18 communities around Ghana Atomic Energy Commission. The radon detectors were deployed in the bed and sitting 
rooms for six months, twice a year from April to September and October to March as rainy and dry seasons respectively. The dwellings 
were randomly chosen based on accessibility and support from the occupant. For each dwelling, a radon detector was deployed in 
either sitting or bedroom (s). The detector was exposed to 1–1.5 m a height above the floor equivalent to the breathing height of the 
person, at 0.5 m greater than the distance apart within the room, and 15 cm smaller than from any other items [5,20,21,32]. The 
detectors were placed in a location evading excessive ventilation. The building features such as room size, structures, building ma-
terials, age, and ventilation systems were noted during the result evaluation. 
2.4.3.2. Radon exhalation rate. Radon exhalation rate from the soil samples was measured by a firmly closed can technique with CR- 
39 of 10 and 25 cm of diameter and height respectively. The measurement was done with known weight of a prepared samples in a can 
covered 78.5 cm2 surface area. Soil samples were closely airtight and kept at room temperature for 4 weeks to enable 226Ra to establish 
equilibrium with its progeny [5,27,32,33]. The radon exhalation was determined by placing the CR-39 at the top of the prepared 
sample in the closed can within the distance of 22 cm from the soil surface. This procedure was used in order to measure only radon 
alpha particles detected on the track density and stop thoron progeny from touching the surface of the CR-39 [5,27,32,33,42]. The 
radon exhalation rate measurement was done for ninety days. 
2.4.4. Etching and radon concentration estimation 
The detector film was detached and etched in a 6.25 mol NaOH prepared solution of 4000 ml of distilled water with 1000 g pellet 
sodium hydroxide at 90 ◦C for 4 h and 30 min to broaden the tracks that form on the exposed detectors as a result of the alpha particles 
produce from radon daughters [5,27,32,33,40,42]. The films were dried for four days. The latent tracks formed on the detector films 
were scanned with RadoMeter and counted in 144 fields by means of an optical microscope with a 40 times magnification objective 
lens. The track density from the unexposed radon detector as a background was measured under the similar etching condition. The 
track density from each detector film was then used to estimate indoor radon concentration and radon exhalation rate from the 
dwellings and soils using equations (2) and (3) [5,27,32,33,42]. 
ϱ
Indoor Radon Concentration (C)= (2)  
ϵt
ϱV λ
Radon Exhalation rate E c Rn( )= ε (3)  SaTc
where, V volume of diffusion chamber (m3c ), Sa surface area of the sample (m2), λRn decay constant of radon (1/s) ϵ calibration factor of 
the CR-39 (track/cm2d/(Bq/m3), ϱ measured surface density of tracks (tracks/cm2), Tc effective exposure period (s) in the diffusion 
chamber and t exposure period 
2.5. Factors that affect ventilation rate 
The ventilation effect on indoor radon gas in dwellings was estimated by considering similar factors in the 69 dwellings within 18 
communities of the studied areas. The factors used to explore the ventilation differences in the room of dwellings were: doors, win-
dows, and building materials such as sandcrete, concrete, clay, and wooden structures. The rooms with one (1) door and window were 
considered poorly ventilated while 2 or more doors and windows were duly classified as well ventilated rooms. At least four rooms 
made up of different ventilation settings were chosen from each studied community. Indoor radon concentrations were determined in 
the same procedure as stated previously. 
2.6. Spatial radon mapping 
The software used in the processing and aggregation of the radon concentration is ArcMap geostatistical interpolation tool. Using 
inverse distance weight (IDW) interpolation the data from unsampled areas was used to generate a contiguous raster to cover the study 
area. This was then captured in a 50 × 50-m grid and the intensity of radon distributions within communities of the Ghana Atomic 
Energy Commission was developed. Choropleth maps were generated using the range of radon intensity values [11–14]. 
2.7. Data statistical analysis 
The Statistical tool used for the analysis of this data includes the Pearson correlation coefficient and Principal components which 
were performed with SPSS (version 23) [43,44]. This is to know the dependence of indoor radon and radon exhalation on radium-226 
concentration within the seasonal periods [5,32,33]. It was also to determine the magnitude of the radon and radium existence in the 
dwellings, soil as well as the contribution of the radon exposure to the occupants. 
4
F. Otoo et al.                                                                                                                                                                                                  H   e l i y  o  n 9 (2023) e15259
2.8. Determination of the effective doses 
The annual effective dose (AD) was estimated based on the mean indoor radon concentration from the study location. The effective 
doses were calculated from the proposed equation (4) by UNSCEAR [1]. 
AD =C × Oif × Dcf × Iof × Thy (4)  
where Oif indoor occupancy factor (0.8); C average indoor radon concentration (Bq/m3); Thy number of hours per year (8760 h/yr) 
[45]; Icf equilibrium factor (0.4) [1] and Dcf dose conversion factor 9 nSv/(Bq h m− 3) [1]. 
The estimation of the resultant annual effective dose to lungs (AL) due to indoor radon exposure to the residents was done using 
equation (5). 
AL =AD × Wr×Wt (5)  
where Wr radiation weighting factor of a value of 20 for alpha particles, AD annual effective dose (mSv/yr); and Wt tissue weighting 
factor of 0.12 for lungs [3,46]. 
3. Result and discussion 
3.1. Activity concentration of radium and seasonal radon 
Results from 18 communities around the Ghana Atomic Energy Commission are presented as the average, range, seasonal radon 
exhalation (E), seasonal indoor radon (C), and radium concentrations presented in Table 1. The result for seasonal indoor radon 
variations for CR (rainy) and CD (dry) with mean values ranging from 28.9 to 177.2 Bq/m3 (78.1 ± 38.7 Bq/m3) and 24.4–125.5 Bq/m3 
(69.9 ± 24.2 Bq/m3). 
Result from indoor radon, radon exhalation, and radium concentrations showed the distributions are not uniform throughout the 
study areas as indicated in frequency distribution graphs and mapping as depicted in Figs. 2–5. Spatial distribution of the radon map 
revealed that the radon gas within the study was not uniformly distributed indicating that radon gas exposure levels to the residence 
within the rooms are not the same. The spatial distribution of the radon map was done by applying the gridded approach. The radon 
levels were described by displaying the various levels of intensity of estimated mean indoor radon concentration within the locality for 
each grid area as depicted in Fig. 5. 
The non-homogeneous distribution levels of radium and radon in soils and dwellings could be attributed to the cracks in floors and 
walls, occupancy behavior such as opening and closing of the door and windows, soil permeability, moisture contents, and geological 
conditions [5–7,47–49]. It may be attributed to the radium concentration differences in construction materials and soil that existed 
below the dwellings [5,32]. The average values from the study were all found to be less than the reference level from WHO, but 3 study 
locations recorded values greater than the reference value. The highest and lowest indoor radon was obtained in GHG and GHD 
communities within the rainy and dry seasons respectively. Closing of windows and doors leading to poor air circulation between 
indoor and outside environments may contribute to the highest indoor radon, [5,16,17,20,30,32,50]. Moreover, during the rainy 
Table 1 
Average radium concentrations, seasonal radon levels in soils, dwellings, and annual effective doses.  
LC Samples Description Average Seasonal Radon Levels Radium Con. Effective Dose (mSv/y) 
SS DS Indoor Radon (Bq/m3) Radon Exhalation (μBq/m2 h) 226Ra (Bq/kg) AD AL   
CR CD ER ED    
TEE 5 10 51.1 ± 19.1 45.7 ± 18.7 56.5 ± 18.7 55.2 ± 18.7 8.1 ± 7.8. 0.9 ± 0.1 2.1 ± 0.1 
PEE 3 7 37.9 ± 3.5 24.4 ± 3.9 96.7 ± 18.7 60.4 ± 18.7 11.8 ± 4.7 1.2 ± 0.1 3.0 ± 0.2 
MED 3 11 98.3 ± 22.8 75.8 ± 31.2 43.4 ± 18.7 62.7 ± 18.7 22.6 ± 13.3 2.1 ± 0.3 5.2 ± 0.4 
GHD 6 12 51.1 ± 19.1 45.9 ± 18.7 39.6 ± 18.7 55.8 ± 18.7 8.2 ± 7.9 1.5 ± 0.2 3.6 ± 0.4 
GEE 4 9 44.2 ± 8.2 53.5 ± 22.6 57.7 ± 6.1 71.6 ± 8.2 12.9 ± 1.5 3.0 ± 0.4 7.2 ± 0.7 
GDD 6 14 104.4 ± 78.7 63.1 ± 26.3 64.8 ± 5.1 67.6 ± 5.7 10.8 ± 7.0 3.8 ± 0.5 9.2 ± 0.8 
GFD 4 9 130.8 ± 54.8 102.1 ± 38.4 59.8 ± 4.7 105.6 ± 11.7 38.5 ± 4.5 1.4 ± 0.1 3.3 ± 0.2 
GHG 3 6 132.5 ± 87.2 104.3 ± 79.6 74.7 ± 8.0 89.9 ± 8.9 29.3 ± 21.5 1.5 ± 0.2 3.6 ± 0.2 
EGG 5 11 66.1 ± 29.4 51.9 ± 33.8 42.9 ± 1.7 80.3 ± 7.7 20.9 ± 10.6 1.2 ± 0.1 3.0 ± 0.3 
EGR 4 13 96.8 ± 49.2 89.3 ± 11.0 69.8 ± 8.1 100.4 ± 8.9 35.4 ± 6.3 1.8 ± 0.3 4.3 ± 0.5 
GED 6 14 61.4 ± 42.4 64.6 ± 20.4 79.7 ± 6.7 88.9 ± 9.9 18.1 ± 13.4 1.8 ± 0.3 4.3 ± 0.4 
GAQ 5 13 74.0 ± 28.6 68.9 ± 26.3 87.6 ± 7.7 99.9 ± 9.7 20.3 ± 3.9 1.8 ± 0.3 4.3 ± 0.3 
GFE 3 7 74.6 ± 68.1 67.2 ± 42.2 100.3 ± 9.7 99.7 ± 6.7 24.0 ± 24.0 2.3 ± 0.3 5.6 ± 0.4 
ADW 4 6 28.9 ± 2.6 68.6 ± 53.9 98.8 ± 7.7 94.7 ± 8.7 18.5 ± 16.5 1.6 ± 0.3 3.8 ± 0.4 
GWC 5 8 56.3 ± 27.0 51.1 ± 24.3 68.9 ± 5.7 93.6 ± 8.7 18.8 ± 10.2 1.1 ± 0.1 2.6 ± 0.3 
TDD 3 8 49.2 ± 33.3 69.1 ± 24.1 88.9 ± 8.7 100.3 ± 9.7 24.3 ± 8.7 2.4 ± 0.3 5.6 ± 0.6 
VVD 3 9 70.7 ± 49.2 69.8 ± 11.0 75.6 ± 6.7 78.8 ± 7.7 18.0 ± 6.3 2.2 ± 0.2 5.3 ± 0.5 
GHC 5 11 177.2 ± 91.0 125.5 ± 65.1 49.8 ± 4.7 111.9 ± 12.7 42.2 ± 12.5 2.9 ± 0.3 7.1 ± 0.8 
Average   78.1 ± 38.7 68.9 ± 24.2 69.9 ± 19.4 77.1 ± 18.7 21.3 ± 9.9 1.9 ± 0.8 4.6 ± 1.3 
DS: Number of monitored dwellings and SS: Number of studied soil samples. 
5
F. Otoo et al.                                                                                                                                                                                                  H   e l i y  o  n 9 (2023) e15259
Fig. 2. Indoor radon frequency distribution.  
Fig. 3. Radon exhalation frequency distribution in soils.  
Fig. 4. Frequency of distribution of radium concentration.  
6
F. Otoo et al.                                                                                                                                                                                                  H   e l i y  o  n 9 (2023) e15259
Fig. 5. Radon mapping of the study areas.  
season, the soil becomes water statured resulting in the radon gas moving to dry areas beneath the underlying building, which may also 
be accounted for higher indoor radon gas. Higher radium concentration within the study location may be the cause for the increase in 
the radon levels [5,32]. Circulation of the air in and out of the rooms may be accounted for the lowest indoor radon value [30]. 
The average seasonal radon exhalation for ER (rainy) and ED (dry) with mean values ranging from 39.6 to 100.3 (68.9 ± 24.2 μBq/ 
m2 h) and 55.2 to 111.9 (77.1 ± 18.7 μBq/m2 h). The radium concentrations with mean values were in the range of 8.1–42.2(21.3 ±
9.9 Bq/kg). The communities of GHC and GHD obtained highest and lowest radon exhalation rate within the dry and rainy seasons. 
Radium concentration recorded the highest and lowest value in locations GHC and TEE respectively. It was noticed from the result of 
the study that where radium concentration increases, radon exhalation was found to be also increasing, especially during the dry 
season presented in Table 1. Highest radon exhalation rate obtained in the dry season may be credited to the highest radium content 
and larger pores space existing within the soil [24,27,28] while the lowest value recorded in the rainy season may be due to high water 
content which affects radon emanation from the soil surface. The average radon exhalation values from this work were smaller than the 
average of 125 μBq/m2h proposed by UNSCEAR [1]. The maximum radium concentration from the study was more than 0.9 times 
Fig. 6. Variation of ventilation within the study dwellings.  
7
F. Otoo et al.                                                                                                                                                                                                  H   e l i y  o  n 9 (2023) e15259
greater while the smallest value was found to be 4.9 times lower than the 40 Bq/kg proposed by UNSCEAR indicated in Table 1. 
3.2. Ventilation effects on indoor radon 
The effect of ventilation on radon indoor within the dwellings of different materials was studied. Highest average indoor radon 
concentration was recorded within poorly ventilated concrete room while well ventilated wooden structures obtained the lowest 
average indoor radon concentration as depicted in Fig. 6. Highest and lowest average values recorded in these dwellings were in an 
agreement with similar studies in Ghana [5,16,32]. The lower average radon concentration recorded in both well and poorly ventilated 
wooden dwellings may be attributed to the wood as a building material, not from the earth’s crust, therefore, does not contain sub-
stantial levels of radium concentration [5,16,33,51]. It is indicative, that differences in changes in ventilation conditions in the rooms 
have a substantial influence on indoor radon concentration [30]. It is also evident that radon gas is dependent on the circulation of air 
between indoor and outdoor environments. The differences in the structure of the dwellings such as door, window, and building 
materials may be the cause of the indoor radon variations within the rooms. The highest indoor radon concentration value obtained 
from these studies was found to be well below the proposed maximum value but 4% of the studied rooms obtained values greater than 
the minimum ranged action levels from 200 to 600 Bq/m3 proposed by the ICRP [3]. The 22% of the results were greater than the WHO 
reference level of 100 Bq/m3 [2]. 
3.3. Seasonal indoor radon variation 
Seasonal indoor radon variations showed the dry season had the highest frequency distribution of 36% within range values of 0–40 
Bq/m3 as depicted in Fig. 7 while 30% of the result obtained in the rainy season recorded the highest frequency distribution in the 
range of 0–40 Bq/m3 as also depicted in Fig. 7. The 3% and 2% of the dwellings from both rainy and dry seasons recorded the lowest 
indoor radon distributions from the range of 240–280 Bq/m3 shown in Fig. 7. The result of the seasonal variation indicated that the 
rainy season, had 22% of the indoor radon values while the dry season recorded 16% of the values more than the 100 Bq/m3 as 
proposed by from WHO. presented in Fig. 7. Higher radon concentration recorded in the rainy season may be due to the fact that during 
rains the soil becomes water statured which causes the movement of radon gas from wet to dry areas beneath the underlying dwellings. 
This may result in blocking the radon gas from emanating through the soil surrounding the dwelling, thereby forcing most of the radon 
gas to pass through the dry soil beneath buildings or plumbing pipelines or cracks within the dry foundation with higher permeability 
[16,17,20,30,50]. Most of the windows and doors are also closed during the rainy season resulting in poor ventilation. These phe-
nomena may cause the building up of radon gas as a result of the building materials as well as the soil beneath the dwellings, resulting 
in higher indoor radon gas in the room during the rainy season [7,16–18,22]. Lower values obtained in the dry season may be due to 
the circulation of air between the room and the outdoor environment due to frequently opening of the windows and doors [16,30,50]. 
Higher indoor radon concentrations within the rainy season were also in agreement with similar work conducted in other parts of 
Ghana [16,17,20]. 
3.4. Statistical analysis of radium and seasonal radon levels 
3.4.1. Correlation analysis 
Pearson’s statistical correlation coefficient was used to study the linkage that exists between the radium concentration, and sea-
sonal radon levels present in the studied dwellings and soils. 
The correlation result is presented and described in Table 2. Pearson’s positive correlation result was found to exist in the pair of 
radium concentrations with seasonal radon levels present in the dwellings and soils. The positive correlation associated with this study 
may attribute to the radon concentration coming from the decay series of the 226Ra which is the direct daughter of 222Rn as stated in 
Table 2. A positive correlation resulting from the Pearson analysis between radium concentration and seasonal indoor radon indicated 
that radium content existing in the soil contributes to significant levels of radon exposure to the residents. In other words, increasing 
Fig. 7. Variation of season indoor radon concentration.  
8
F. Otoo et al.                                                                                                                                                                                                  H   e l i y  o  n 9 (2023) e15259
Table 2 
Correlation between seasonal radon concentrations in soil and dwellings with radium concentration.   
C 226R CD Ra ER ED 
CR 1.00     
CD 0.64 1.00    
226Ra 0.76 0.47 1.00   
ER 0.79 0.62 0.73 1.00  
RD 0.72 0.64 0.81 0.72 1.00  
the radium content in the soil will lead to higher indoor radon gas in dwellings [5,26,27]. 
The highest and lowest positive correlation values of 0.81 and 0.47 were found to be between the correlation of radium concen-
tration with radon exhalation (ED) and indoor radon (CD) in soils and dwellings of the dry season respectively. The highest coefficient 
may be due to the direct radon exhalation resulting from the radium concentration present in the soil. The lowest coefficient recorded 
in radium concentration with indoor radon within the room might not come from only underlying soil below the dwellings but also 
from construction materials. This result is in agreement with similar studies [5,26,32]. Variations in the correlation coefficient may be 
due to differences in soil properties, occupant lifestyle, dwelling characteristics, ventilation conditions, and building materials [5, 
22–26,47–50]. The higher correlation coefficient values were recorded between indoor radon concentration with radon exhalation 
than with radium concentration. Result may link to radon gas mobility nature as compared to the radium concentration which is 
permanently present in the soil. 
3.4.2. Clustering analysis 
Cluster analysis in the form of a dendrogram was used to determine the similarity between E , E , 226R D Ra, CR, and CD. From the 
dendrogram in Fig. 8, there were two (2) clusters, and the first cluster is composed of E , E , and the 226R D Ra, which is linked to them 
externally, implying that the three variables are directly correlated. It also indicates that radon exhalation rates from the soil are highly 
dependent on the radium concentration [5,26,27,32]. Study result was in line with the report by Otoo et al., 2022, 2020, 2018 [5,32, 
33] and Farid [30]. Indoor radon concentration for rainy and dry seasons (CR and CD) was obtained as the second cluster. These two 
clusters are linked to each other with a high degree of similarity. This is an indication that during the rainy and dry seasons, indoor 
radon gas may be coming from the same origin such as building materials and the underlying soil beneath the buildings. The result is in 
line with Pearson’s correlation result presented in Table 2 and Fig. 8. 
3.3.3. Principal component analysis 
The discrepancies associated with the study data were determined using Principal Component Analysis (PCA). The statistical tool 
was used to study the linkage and to identify the variables of radium concentration, seasonal radon levels present in dwellings and soils 
by applying varimax rotation with the Kaiser Normalization Method [5,27,45]. The PCA result as shown in Fig. 9, indicated only one 
component from the automatic selection tool of SPSS with an eigenvalue greater than 1. 
One directional component existed for the C 226D ER, ED, Ra, and CR, which was in agreement with the Pearson analysis that 
accounted for the only positive correlation coefficient values that occurred in the radium concentration with seasonal indoor and l 
radon exhalation rate as presented in Table 2. Further distance of CD from E 226R, ED, Ra, and CR, indicated that during the dry season, 
most of the indoor concentration present in the rooms may come from the soil underlying the building. 
3.3.4. Scree plot analysis 
The factor analysis for radium content with seasonal indoor radon and seasonal radon exhalation rate shows that the data flattens 
after the second component as depicted in Fig. 10; thus, indicating that two factors were extracted from the study data as shown in 
Table 3. The first factor consists of E 226R, ED, Ra, and CR accounting for a total variance of 81.013% whiles the second factor accounts 
for 9.061% and is highly loaded on CD as shown in Fig. 10 and Table 3. The flattening after the second component and the lower total 
variance may be the same reason attributed to the further distance between ER, ED, 226Ra, CR, and CD in the component analysis shown 
in Fig. 10. 
3.4. Annual effective doses 
The annual effective dose (AD) associated with indoor radon gas to the residents ranging from 0.9 to 2.9 mSv, with a mean of 1.9 ±
0.8 mSv/yr presented in Table 1. The highest and lower values were found in TEE and GDD. Estimated lung annual effective dose (AL) 
was found to range from 2.1 to 9.2 with an overall mean of 4.6 mSv/yr as stated in Table 1. The 3 communities recorded the average 
annual effective doses bigger than the proposed lower range value of 3 mSv/yr from the ICRP 3 and 2.4 mSv/yr world average value 
proposed by UNSCEAR [1]. The overall mean value of 1.9 mSv/yr was recorded for this study shown in Table 1 and found to be 1.6 and 
1.3 times smaller than the lower action level and world average values recommended by ICRP and UNSCEAR. 
3.5. Comparison study with national and international data 
Comparing this study this work with other studies in Ghana, showed that indoor radon varies in dwellings from one location to 
9
F. Otoo et al.                                                                                                                                                                                                  H   e l i y  o  n 9 (2023) e15259
Fig. 8. Clustering of radon and radium concentration variables.  
Fig. 9. Component plot in the varimax – rotated space.  
Fig. 10. Scree plot of radium and radon data.  
another presented in Table 4. The result of this study agrees with the studies compared. The radium concentration from this study was 
found to be 1.3 and 1.4 times less than the data from the Greater Accra and Accra Metropolis in Ghana. In comparison with other results 
from different countries, this work recorded radium concentration smaller than the lower range values from Ethiopia [55] and Kosovo 
[53] Saudi Arabia [26], and Cameroon [54] but greater than studies from Saudi Araba and Cameroon. The maximum range values 
were all found to be greater than the current result from Ghana. 
The average value from the current study was found to be greater than all the results compared with other countries except the 
study from Kosovo which had an average value 1.6 times lower than the current study. Season indoor radon values from this study 
were greater than the similar work from Accra Metropolis [28] but less than the reported seasonal studies from the GA East district 
10
F. Otoo et al.                                                                                                                                                                                                  H   e l i y  o  n 9 (2023) e15259
Table 3 
Rotated component ladings and explained variance for variables.  
Variable Component 
1 2 
CR 0.887 0.351 
CD 0.311 0.914 
226Ra 0.687 0.600 
ER 0.902 0.310 
ED 0.731 0.620 
Eigen value 4.051 0.453 
Total Variance (%) 81.013 9.061 
Cumulative (%) 81.013 90.074  
Table 4 
Comparison of the radium, indoor radon, radon, exhalation, annual effective doses, and with other countries and Ghana.  
Study Area Country 226Ra (Bq/m3) C (Bq/m3) E (μBq/m2 h) AD (mSv/yr) 
Rajasthan [18] India – 143.2 - 1.9 × 10− 3 
Karnataka [19] India  10 - 0.28 
Obuasi [17] Ghana  50.5–152.0 - 0.6–3.90 
Accra Metropoli’s [18] Ghana  28.3  – 
Abirem [20] Ghana 29.0 ± 16.0 54.7 65.1 ± 27.6 1.21 ± 0.2 
Meghalava [50] India  55.9  1.8 
South Dayi [52] Ghana  34.9 - 0.15–1.40 
Sombo & Jirapa [53] Ghana – 57.0 & 32.3 - 0.7 & 1.52 
Kpong [54] Ghana  39.2 - 1.89 
Dome [55] Ghana  466.9 ± 1.2 –  
Kassena Nakana [56] Ghana  130 – – 
Greater Accra [5,33] Ghana 27 77 87 ± 40 – 
77–112.0 
GA-East [20] Ghana – 133.4&721 - 6.9 & 9.8 
Metohija [57] Kosovo 32 (13) 128 - – 
Jeddah city [26] Saudi Arabia 18.0–33.0 21–52 (36) - 0.35–0.89 
Lomié [58] Cameroon 19.6–63.8 (34.8) 30–300 (65) - 0.23–0.72 (0.42) 
Wolaita Sodo [59] Ethiopian 89.3–522.1 (264.5) 30.8–708.1 (236.7) - – 
This study Ghana 21.3 77.9 &69.9 69.9&77.1 1.9 ± 0.8  
[20]. The result from the current study was far less than the studies in comparison except for the reported data from the 
Kassena-Nakana [56], Dome [55], and GA East in the greater Accra region. The current result was also found to be greater than the 
compared lower range values from other countries but less than the maximum range values from Ethiopia and Cameroon as presented 
in Table 4. The average values for the two seasons were found to be more than the compared studies from other countries except for the 
result from Ethiopia which had values 3 and 4 times greater than the current study from Ghana. Radon exhalation rate result was 
greater than the work reported in Abirem [20], but less than the research work reported in greater Accra as shown in Table 4. This 
study obtained values fall within the range of data report from Oyibi and Pokase [33] in the greater Accra region. The radiological data 
associated with the indoor radon concentrations from this study reported an average annual effective dose greater than other studies 
compared in Ghana apart from the result from GA East which was found to be 3.6 and 5.2 times more than the dose from this study 
shown in Table 4. In general radium studies from Ghana were less than the values from other countries. Indoor radon data from 
GA-East of Ghana recorded a value greater than all the studies in comparison. Radon exhalation rate value from the greater Accra 
region was greater than others from Ghana while the GA-East in the same region obtained results far less than the studies from other 
countries. 
4. Conclusion 
The radium concentration, seasonal indoor radon, radon exhalation, mapping, and radon distribution in dwellings and soils around 
the Ghana Atomic Energy Commission have been studied. The radium content and radon levels were found to be not uniformly 
distributed. This work was compared with similar studies in Ghana and other countries. The maximum and smallest seasonal indoor 
radon concentrations were recorded within the rainy and dry seasons. Dwellings with poor ventilation recorded higher seasonal indoor 
radon than well-ventilated rooms. The overall mean radium and indoor radon concentration within the study locations obtained values 
less than the reference levels recommended by the WHO and UNSCEAR. The four communities recorded average indoor radon values 
bigger than the recommended reference level from WHO. A positive correlation was found to exist between radium concentration and 
radon levels in dwellings and soils. One directional component and positive correlation were found to be associated with all the study 
parameters with dry season recorded higher and lower coefficient values in radium with radon exhalation and indoor radon. Two 
clusters were observed between radium concentration with seasonal radon levels in dwellings and soils. Pearson’s correlation results 
11
F. Otoo et al.                                                                                                                                                                                                  H   e l i y  o  n 9 (2023) e15259
were in agreed with the principal component and cluster factor analysis. Annual effective doses were also found to be less than the 
proposed dose limit by ICRP. Statistical analysis indicated that radium concentration was found to have significant effects on radon 
levels in soil and buildings. However, dwellings with indoor radon levels higher than the reference levels of WHO, are highly rec-
ommended to ensure effective improvement in the indoor ventilation conditions to reduce or prevent any risk of developing lung 
cancer in the future. 
Author contribution statement 
Francis Otoo: Conceived and designed the analysis; Analyzed and interpreted the data; Performed experiment; Contributed re-
agents, materials, analysis tools or data; Wrote the paper. 
Rita Kpordzro: Performed the experiments; Contributed reagents, materials, analysis tools or data: wrote the paper. 
A.S.K. Amable; Analyzed and interpreted the data; Contributed reagents, materials, analysis tools or data; wrote the paper. 
Funding statement 
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. 
Data availability statement 
Data included in article/supplementary material/referenced in article. 
Declaration of interest’s statement 
The authors declare no conflict of interest. 
Acknowledgments 
The authors are very grateful to the RPI/GAEC, and the residents for the availability of their facilities and dwelling for this study. 
References 
[1] United Nations Scientific Committee on the Effects of Atomic Radiation, Ionizing radiation: exposure due to natural radiation sources, in: UNSCEAR 2000 
Report, United Nations, New York, 2000. 
[2] World Health Organization, Handbook on Indoor Radon. A Public Health Perspective, WHO, Switzerland, 2009. 
[3] International Commission on Radiological Protection, Protection against radon-222 at home and at work, in: ICRP Publication No.60?, Pergamon Press, Oxford, 
1993. 
[4] International Agency for Research (IARC), Monographs on the Evaluation of Carcinogenic Risk to Humans, 65, 1996. 
[5] F. Otoo, E.O. Darko, M. Garavaglia, Correlation analysis of natural radionuclides, radon exposure, soil particles and moisture from quarry towns in greater Accra 
region, Ghana, Water, Air, Soil Pollut. 233 (8) (2022) 338, https://doi.org/10.1007/s11270-022-05791-7. 
[6] M. Hosoda, M. Shimo, M. Sugino, M. Furukawa, M. Fukushi, Effect of soil moisture content on radon and thoron exhalation, J. Nucl. Sci. Technol. (Tokyo, Jpn.) 
44 (4) (2007) 664–672, https://doi.org/10.1080/18811248.2007.9711855. 
[7] A. Louizi, D. Nikolopoulos, H. Lobotessi, C. Proukakis, Factors affecting indoor radon concentration in Greece, Radon in the living environ 272 (2001) 1–3. 
[8] H. Wang, L. Zhang, P. Gao, Q. Guo, A pilot survey on indoor radon concentration in Beijing, Rad. Med. Prot. 3 (2022) 22–25, https://doi.org/10.1016/j. 
radmp.2022.01.003. 
[9] National Research Council Committee on Health Risks of Exposure to Radon (BEIR VI), Health Effects of Exposure to Radon: BEIR VI. (DC), in: National 
Academies Press (US); Appendix E, Exposures of Miners to Radon Progeny, 1999. https://www.ncbi.nlm.nih.gov/books/NBK233269/. 
[10] W. Jacobi, The history of the radon problem in mines and homes, Ann. ICRP 23 (2) (1993) 39–45. 
[11] F. Giustini, G. Ciotoli, A. Rinaldini, L. Ruggiero, M. Voltaggio, Mapping the geogenic radon potential and radon risk by using Empirical Bayesian Kriging 
regression: a case study from a volcanic area of central Italy, Sci. Total Environ. 661 (2019) 449–464, https://doi.org/10.1016/j.scitotenv.2019.01.146. 
[12] A. Lima, B. De Vivo, D. Cicchella, M. Cortini, S. Albanese, Multifractal IDW interpolation and fractal filtering method in environmental studies: an application on 
regional stream sediments of (Italy), Campania region, Appl. Geochem. 18 (2003) 1853–1865, https://doi.org/10.1016/s0883-2927(03)00083-0. 
[13] R. Borgoni, P. Quatto, G. Somà, D. De Bartolo, A geostatistical approach to define guidelines for radon prone area identification, J. Ital. Stat. Soc. 19 (2009) 
255–276, https://doi.org/10.1007/s10260-009-0128-x. 
[14] F. Loffredo, A. Scala, G.M. Adinolfi, F. Savino, M. Quarto, A new geostatistical tool for the analysis of the geographical variability of the indoor radon activity, 
Nukleonika 65 (2020) 99–104, https://doi.org/10.2478/nuka-2020-0015. 
[15] J. Miles, K. Ball, Mapping radon-prone areas using house radon data and geological boundaries, Environ. Intern 22 (1) (1996) 779–782. https://doi.org/10. 
1016/S0160-4120(96)00183-3. 
[16] F. Otoo, E.O. Darko, M. Garavaglia, C. Giovani, S. Pividore, A.B. Andam, J.K. Amoako, O.K. Adukpo, J.B. Tandoh, S. Inkoom, Seasonal indoor radon studies in 
buildings of Accra metropolis of greater Accra region of Ghana, Radioprotection 53 (3) (2018) 199–206. 
[17] I. Opoku-Ntim, A.B. Andam, V. Roca, J.J. Fletcher, T.T. Akiti, Indoor radon concentration and risk assessment in some residences of Obuasi, Mining Town. Rad. 
Prot. Dosim. 188 (1) (2019) 30–370, https://doi.org/10.1093//rpd/ncz254. 
[18] V. Duggal, A. Rani, R. Mehra, A study of seasonal variations of radon levels in different types of dwellings in Sri Ganganagar district, Rajasthan, J. Radia. Res. 
Appl. Sci. 7 (2) (2014) 201–206, https://doi.org/10.1016/j.jrras.2014.02.007. 
[19] D.V. Kamalakar, P.R. Vinutha, C.S. Kaliprasad, Y. Narayana, Seasonal Variation of Indoor Radon, Thoron and Their Progeny in Belagavi District of Karnataka, 
India 194, Environ Monit Assess, 2022, p. 310, https://doi.org/10.1007/s10661-022-09931-8. 
[20] R. Kpordzro, J.K. Gbadago, A.B. Andam, O.K. Adukpo, F. Otoo, I. Opoku-Ntim, M. Abubakar, E. Amoatey, Assessment of Seasonal Radon Concentration in 
Dwellings and Soils in Selected Areas in Ga East, Greater Accra Region of Ghana, J. of Environ. Pub. Health, 2022, p. 9, https://doi.org/10.1155/2022/ 
6600919. 
[21] I. Yarmoshenko, G. Malinovsky, A. Vasilyev, A. Onishchenko, Seasonal variation of radon concentrations in Russian residential high-rise buildings, Atmos 12 
(2021) 930, https://doi.org/10.3390/atmos12070930. 
12
F. Otoo et al.                                                                                                                                                                                                  H   e l i y  o  n 9 (2023) e15259
[22] C.Y. King, A. Minissale, Seasonal variability of soil gas radon concentration in Central California, Radiat. Meas. 23 (4) (1994) 683–692. 
[23] R. Fujiyoshi, K. Sakamoto, T. Imanishi, T. Sumiyoshi, S. Sawamura, J. Vaupotic, I. Kobal, Meteorological parameters controlling variability of 222Rn activity 
concentration in soil gas at a site in Sapporo, Japan. Sci. Tot. Env. 370 (1) (2006) 224–234. 
[24] J.W. Washington, A.W. Rose, Regional and temporal relations of radon in soil gas to soil temperature and moisture, Geophys. Res. Lett. 17 (6) (1990) 829–832. 
[25] M.E. Kitto, Interrelationship of indoor radon concentrations, soil-gas flux, and meteorological parameters, Radio. Nucl. Chem. 264 (2) (2005) 381–385. 
[26] S.M. Farid, Indoor radon in dwellings of Jeddah city, Saudi Arabia and its correlations with the radium and radon exhalation rates from the soil, Indoor Built 
Environ. 25 (1) (2016) 269–278, https://doi.org/10.1177/1420326X14536749. 
[27] F. Otoo, E.O. Darko, M. Garavaglia, O.K. Adukpo, J.K. Amoako, J.B. Tandoh, S. Inkoom, S. Nunoo, S. Adu, Assessment of natural radioactivity and radon 
exhalation rate associated with rock properties used for construction in Greater Accra Region, Ghana, J. Radioanal. Nucl. Chem. 328 (2021) 911–923, https:// 
doi.org/10.1007/s10967-021-07709-9. 
[28] J. Dolejs, J. Hulka, The weekly measurement deviations of indoor radon concentration from the annual arithmetic mean, Radiat. Protect. Dosim. 104 (2003) 
253–258. 
[29] A. Baeza, E. Navarro, C. Roldán, J.L. Ferrero, D. Juanes, J.A. Coebacho, F.J. Guillén, Indoor radon levels in buildings in the autonomous community of 
Extremadura (Spain), Radiat. Protect. Dosim. 103 (3) (2003) 263–268. 
[30] R. Mehra, P. Bala, Effect of ventilation conditions on the annual effective dose due to indoor radon concentration, Adv. Appl. Sci. Res. 4 (1) (2013) 212–215. 
[31] A. Azhdarpoor, M. Hoseini, S. Shahsavani, N. Shamsedini, E. Gharehchahi, Assessment of excess lifetime cancer risk and risk of lung cancer due to exposure to 
radon in a middle eastern city in Iran, Rad. Med. Prot. 3 (2021) 112–116, https://doi.org/10.1016/j.radmp.2021.07.002. 
[32] F. Otoo, I. Arhin, E.O. Darko, Studies of radon levels, radium concentration and estimated effective dose in dwellings and soils in gold mining towns in Abirem of 
Eastern region of Ghana, Radiat. Protect. Dosim. (2020) 1–14, https://doi.org/10.1093/rpd/ncaa129. 
[33] F. Otoo, E.O. Darko, M. Garavaglia, C. Giovani, S. Pividore, A.B. Andam, J.K. Amoako, O.K. Adukpo, S. Inkoom, S. Adu, Public exposure to natural radioactivity 
and radon exhalation rate in construction materials used within Greater Accra Region of Ghana, Sci Afri 1 (2018), e00009. 
[34] K.B. Dickson, G. Benneh, A New Geography of Ghana, Longmans Group Limited, London, UK, 2004. 
[35] G.O. Kesse, The Mineral and Rock Resources of Ghana, A. A Balkema, Rotterdam, Netherlands, 1985. 
[36] Ghana Statistical Service (GSS), Ghana Statistical Service on Population and Housing Census of District-Level Analytical Reports on Metropolitan, Municipal and 
District Assemblies, Accra, Ghana, 2014. 
[37] C. Bangou, F. Otoo, E.O. Darko, Performance testing and comparative study of natural radioactivity in soil samples using high purity germanium (HPGe) 
detector, MethodsX 8 (2021), 101397. 
[38] Eckert, Ziegler Nuclide Mixtures NG1 to NG6, 2011. 
[39] O. Sima, D. Arnold, C. Dovlete, GESPECOR, A versatile tool in gamma-ray spectrometry, J Radio.Nucl Chem 248 (2001) 359–364. 
[40] S.A. Durrani, R. Ilic, Radon Measurements by Etched Track Detectors, World Scientifc Publishing Co, 1997. 
[41] RADOSYS Operating Manual, Radosys/Radometer 2000 System, 2013. 
[42] Atomic Energy Commission Inaugurates Radon Monitoring Laboratory, 2019. https://gaecgh.org/atomic-energy-commission-inaugurates-radon-monitoring- 
laboratory/. 
[43] J.E. Jackson, A User’s Guide to Principal Components, 39, Wiley, New York, 1991. 
[44] Multivariate Data Analysis, Kluwer Murtagh and Heck, Dordrecht, 1987. Multivariate data analysis, Kluwer, http://strule.cs.qub.ac.uk/~fmurtagh/books/ 
holdall.pdf. 
[45] World Health Organization, 2015. http://www.who.int/countries/gha/en. 
[46] International Commission on Radiological Protection, Annals on Recommendations of the ICRP, 2007, pp. 2–4. https://www.icrp.org/docs/ICRP_Publication_ 
103. 
[47] G.M. Douglas, W.M. George, Prediction of indoor radon based on soil radon and soil permeability, J. Envir. Sci. Health, Part A. 34 (6) (1999) 1253–1266, 
https://doi.org/10.1080/10934529909376894. 
[48] W. Zhang, Y. Zhang, Q. Sun, Analyses of influencing factors for radon emanation and exhalation in soil, Water Air Soil Pollut. 230 (2019) 16, https://doi.org/ 
10.1007/s11270-018-4063-z. 
[49] D.G. Mose, G.W. Mushrush, J.E. Slone, Environmental factors governing indoor radon, J. Env. Sci Health, Part A 31 (3) (1996) 553–577, https://doi.org/ 
10.1080/1093452960937637. 
[50] A. Pyngrope, A. Khardewsaw, Y. Sharma, D. Maibam, A. Saxena, B.K. Sahoo, Study of indoor radon, thoron and their progeny in south west khasi hills district of 
Meghalaya, India, Radiat. Protect. Dosim. 189 (3) (2020) 347–353, https://doi.org/10.1093/rpd/ncaa048. 
[51] R.L. Kathren, NORM sources and their origins, Appl. Radiat. Isot. 49 (3) (1998) 149–516. 
[52] C.Y. Ansre, M.K. Miyittah, A.B. Andam, D.E. Dodor, Risk assessment of radon in the south dayi district of the volta region, Ghana, Journal of Rad. Res. Appl Sci. 
11 (2018) 10–17. 
[53] A.B. Yuoni, Assessment of Indoor Radon Activity Concentration Levels in Two Districts of the Upper West Region of Ghana, University of Ghana, Accra, 2014 
https:ugspace.ug.edu. 
[54] D. Kitson-Mills, S. Sovoe, I. Opoku-Ntim, K.A. Kyei, S. Marnotey, S. Anim-Sampong, M.A. Kwabeng, F. Otoo, F. Baiden, An assessment of indoor radon level in a 
suburb of Ghana, Environ. Res. Commun. 1 (2019), 061002. 
[55] I. Nsiah-Akoto, J.J. Fletcher, O.C. Oppon, A.B. Andam, Indoor radon levels and the associated effective dose rate determination at Dome in the Greater Accra 
Region of Ghana, Rev. Environ. Earth Sci. 3 (2) (2011) 124–130. 
[56] F.K. Quashie, J.J. Fletcher, O.C. Oppon, A.B. Asumadu-Sakyi, D.A. Wordson, C.A. Adjei, E.O. Amartey, P. Amponsah, Preliminary studies on indoor radon 
measurements in some adobe houses in the Kassena nankana area of the upper East region of Ghana, Rev. Environ. Earth Sci. 3 (1) (2011) 51–55. 
[57] L. Gulan, J.M. Stajic, F. Bochicchio, C. Carpentieri, G. Milic, D. Nikezic, Z.S. Zora S Zunic, Is high indoor radon concentration correlated with specific activity of 
radium in nearby soil? A study in Kosovo and Metohija, Environ. Sci. Pollut. Res. Int. 24 (2017) 19561–19568, https://doi.org/10.1007/s11356-017-9538-8. 
[58] G. Dieu, D.G. Souffit, J.M. Valdes, B.O. Modibo, Y.S.T. Flore, J.A.B. Félix, Saïdou Shinji, S. Tokonami, Radon risk assessment and correlation study of indoor 
radon, radium-226, and radon in soil at the cobalt–nickel bearing area of lomié, eastern Cameroon, Water Air Soil Pollut. 233 (2022) 196, https://doi.org/ 
10.1007/s11270-022-05666-x. 
[59] N. Nigus Maregu, L. Nebere, N. Abeje, B. Dessalegn, T. Yibka, Investigation of radon concentrations and effective radium content in soils and dwellings of 
Wolaita Sodo Town, Ethiopia, J Radiat. Cancer Res. 10 (2019) 66–71. 
13