




































Asian Review of Environmental 

and Earth Sciences 
ISSN: 2313-8173 
Vol. 1, No. 1, 5-7, 2014 

http://www.asianonlinejournals.com/index.php/AREES 

 
 

 

 

 

 

5 

 

Indoor and Outdoor Gamma Dose Rate Exposure Levels in 

Major Commercial Building Materials Distribution Outlets 

in Jos, Plateau State-Nigeria 
 
D.I.Jwanbot

1
 --- M.M.Izam

2
 --- G.G. Nyam

3
 --- M.Yusuf

4
 

 
1,2,4 Department of Physics, University of Jos-Nigeria 
3Department of Physics, University of Abuja-Nigeria 

 

Abstract 

 

 

 

 

 

 

 

 

 

 

 

 

 
 

 

 

 

 
This work is licensed under a Creative Commons Attribution 3.0 License 

Asian Online Journal Publishing Group 
 

1. Introduction 
Radioactive materials containing radionuclides of natural origin are known as NORM (Naturally Occurring 

Radioactive Materials).  Some minerals have significant levels of natural radionuclides that are extracted and 

processed with other elements. Some industries involve processes that concentrate natural radionuclides and then 

may cause some risk to people if their exposure are not under control.  These naturally radioactive materials that are 

concentrated by some industries are known as TENORM (Technological Enhanced Naturally Occurring Radioactive 

Materials).  Although there is a conceptual difference between NORM and TENORM, sometimes the term NORM is 

used referring to TENORM. TENORM is found in some effluent flows and waste from non-nuclear industries, for 

example in metal residues, scales sludge and fluid.  The materials, the by-products and final products from processes 

may enhance the exposure of workers and members of the public.  The most important radioactivity source in 

TENORM is due to the presence of isotope produces of the Uranium and Thorium decay chain. All building 

materials contain various amounts of natural radioactive nuclides. Materials derived from rocks and soils contain 

mainly natural radionuclides of uranium
238

 U and Thorium Th series, and their radioactive isotope of potassium 
40

 K. 

The external radiation exposure is caused by the gamma emitting radionuclide which is the uranium series mainly 

belonging to the decay chain segment starting with 
226

Ra. The internal (inhalation) radiation exposure is due to 
222

Rn 

and marginally to 
220

Rn and their short lived decay products, exhaled from building materials into the air. 

Naturally occurring radioactive materials a widespread substance that can be found everywhere in the 

environment including rocks, soil water, air and also tissues of living things. There are no ways to avoid the presence 

of natural radionuclide since its presence is from the formation of the earth. Man is continuously exposed to ionizing 

radiation from naturally occurring radioactive materials. The origin of these materials is the earth crust, but they find 

their way into building materials, air, water, food and human body itself. Measurement of activity concentrations of 

radionuclides in building materials is important in the assessment of population exposure, as most individuals spend 

80% of their time indoors [1]. In many parts of the world, building materials containing radioactive materials have 

been used for generations. As individuals spend more than 80% of their time indoors, the internal and external 

radiation exposure from building materials creates prolonged exposure situations [2]. Recycled industrial by-

Certain types of building materials are known to be radioactive. Exposures to indoor and outdoor 

radiation like exposure to any other type of ionizing radiation result in critical health challenges. The 

measurements of the indoor and outdoor gamma dose rate exposure levels of various types of building 

materials in the major  commercial  building materials distribution outlets in Jos Plateau was carried-

out. A total number of 56 shops where building materials are sold were surveyed using gamma-scout 

(model GS2 with serial number A20). The range of the radiation levels were: (0.258 - 0.264) mSv/yr 

and (0.218 - 0.226) mSv/yr for floor titles indoor and outdoor respective, (0.226 – 0.25 –0.250) mSv/yr 

and (0.210 - 0.214) mSv/yr for PVC ceiling indoor and outdoor respectively. The average total annual 

effective doses due to outdoor and indoor gamma exposures were 1.80mSv (floor tiles) and 1.64mSv 

(wall tiles) while for wash  hand basin was 1.69mSv/yr, white cement and PVC pipes materials 

recorded the lowest annual effective dose amongst all the others, which is above  1mSv/yr  (the 

acceptable limit for the general public). Hence these could pose some health hazards to the occupants of 

these store/shops.  
 

      Keywords: Dose rate, Building materials, Indoor gamma exposure, Outdoor gamma exposure, exposure       lev level. 

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Asian Review of Environmental and Earth Sciences, 2014, 1(1): 5-7 

 

 

 

 

6 

 

products containing Technologically Enhanced Natural Occurring Radioactive materials are extensively used in the 

construction industry. Coal ash produced as waste in the combustion of coal, is used as an additive to cement in 

concrete and in some countries bricks are made from fly ash. Coal slag is used in floor structures as insulating filling 

material. Phosphogypsum, a by-product in the production of phosphorous, fertilizer is used as building material and 

red mud, a waste from primary aluminum production is used in bricks, ceramics and tiles [3, 4].  Building materials 

cause direct radiation exposure because most of them contain naturally occurring radioactive materials mainly 

radionuclides from 
226

Ra and 
232

Th  decay chains and 
40

K .The world wide average indoor effective dose due to 

gamma rays from building materials is estimated to be about 0.4 mSv per year [5]. Elevated indoor external dose 

rates may arise from high radionuclide content in building materials [6-10]. Generally natural building materials 

reflect the geology of their site of origin. However, elevated levels of natural radionuclides causing annual doses 

several mSv have been identified in some regions around the world e.g. in Brazil, France, India, Nigeria and Iran 

[11]. This external radiation exposure caused by gamma emitting radionuclides in building materials can be assessed 

either by direct exposure measurements in the existing buildings or by radionuclide analyses of building materials 

with dose rate modeling. 

 

2. Materials and Method 
The Rwang-Pam building material shops in Jos North and that of Building Materials, Bukuru in Jos South were 

selected for this study because they are the largest building materials distribution outlets in Plateau State. It is always 

full of daily activities for customers who come from different towns in the State and also from neighboring States to 

buy different building materials for construction purposes. These building materials are usually displayed at the front 

of their shops while their warehouses filled with the materials are located inside the shops. The implication of this 

system of business which is generally practiced by both small and medium size business involves long business hour 

stay time with these materials. Hence, the exposure scenario is of concern given that these materials have element of 

natural radioactive materials with their accompanying nuclear particle emissions. Of greater concern is the confine 

space and poor ventilation that characterized most of these shops and this may lead to high radioactive build up 

especially radon gas concentration. The different shops housing different brands of building materials sold at Rwang-

Pam Street and Building materials market Bukuru were covered in the measurement. The instrument use to perform 

the environmental radiation survey is a gamma scout. The Gamma Scout is a general purpose survey meter that 

measures alpha, beta, gamma and x-ray radiation. It has proven to be useful in medical, nuclear, mining, metal scrap 

and laundry industries.  The gamma scout sets a new standard in portable Geiger counter performances and 

functionality. The gamma scout is calibrated across a wide scale (0.01 up to 1000.00 µSv/hr). Measurement at each 

shop/store was performed by holding the gamma-scout at 1m above to ground surface. Each measurement was taken 

three times and the average taken to represent the value for the shops/stores. 

 

3. Results and Discussion 
The results are as presented in Tables 1 and 2. Exposure of persons due to the presence of these building 

materials in each shops was assessed assuming that exposure was uniformly distributed through-out the year based 

on 12 hours a day, 6 days a week and 52 weeks in a year for salesmen/saleswoman and shopkeepers that stay at their 

sales point from morning to evening and for six days in a week. This is the typical daily routine peculiar to the 

traders at the market. The range and mean values of the indoor and outdoor gamma dose exposure dose rate levels at 

the various shops are presented in Table1, while the annual effective dose values are presented in Table 2. The 

background values in Table 1 indicates that the environment dose rate outside the building of the shop while the 

outdoor values are the dose values where the building materials are usually displayed for sales to prospective buyers. 

From Tables 1 and 2 it could be seen that the indoor doors rates were higher than the outdoor and background values. 

This is a clear indication of the radiation dose contribution due to these building materials that are always in close 

proximity with the store keeper in their shops. As could be seen from the Table 2, the floor tiles and wall tile shops 

exhibit higher dose rate compared to other types of shops.   

The average total annual effective doses due to outdoor and indoor gamma exposures were 1.80mSv (floor tiles) 

and 1.64mSv (wall tiles) while for wash hand basin it was 1.69mSv, white cement and PVC pipes materials recorded 

the lowest annual effective dose amongst all the others, these values were obtained as a result of summation of the 

annual mean indoor gamma dose level with the annual mean outdoor gamma dose level. Increase in effective dose in 

tiles and wash hand basin could be associated with the presence of TENORM in ceramics and the sources of the clay 

origin. The Jos Plateau is thought to be an area of young granite which intruded through an area of older granites 

rock, making up the surrounding state [12].  The presence of the younger granites could also be a factor leading to 

the increase in the effective dose; the volcanic activities of over 50 million years ago and tin mining activities that 

took place before and after the colonial era could also increase the exposure level to workers and other individuals of 

concern. Therefore the scare of tin mining is still evident in plateau state and tin city of Jos, because the State is 

dotted with over 4000 abandoned mining ponds, describe as very dangerous as they contained radioactive materials. 

Control on the radioactivity of building materials can be based on dose criteria for controls and on exemption   

levels. The dose criteria used for control should be defined as the excess exposure caused by building materials, that 

is the background dose from natural radionuclides in the local typical environment need to be subtracted for the 

external gamma radiation, the local typical environment can be defined either as the average dose received outdoor, 

or as the average dose received in a house built from materials with typical activities..  With a median exposure level 

of 0.52mSv arising from building materials at Rwang Pam street market and building materials market Bukuru, a 

dose criterion of 0.82mSv may be considered that will not cause economically and socially intolerable situations on 

the market. When gamma doses are limited to levels below 1mSv/yr. it is recommended that control could be based 

on a lower dose criterion if it is considered that this is desirable and will not lead to impractical control. It is therefore 

recommended that controls should be based on doses in the range of 0.3 –1mSv/yr.  This is the excess gamma dose 



Asian Review of Environmental and Earth Sciences, 2014, 1(1): 5-7 

 

 

 

 

7 

 

to that received outdoors. Building materials should be exempted from all restrictions concerning their radioactivity 

if the excess gamma radiation originating from them increases the annual effective dose of a member of the public by 

0.3mSv [13].  This is the excess gamma dose to that received outdoors. It therefore follow that salesmen and 

shopkeepers at the  major markets in Rwang-Pam street and building materials Bukuru, should spend less time, say, 

about 10 hours or less a day for 6 days in a week throughout 50 weeks in a year, in order to limit their levels of 

exposure.  

 

4. Conclusion 
The radiation dose levels in some selected building materials in Jos have determined using the gamma scout. The 

average effective dose annually received by the shop keepers due to building materials varies from (0.621 – 1.818) 

mSv.  This suggests that some of the building materials in these shops may not have any significant radiation effect 

on the shop keepers while some may have some radiation effects on the shop owners.  

 

References 
[1] R. Mustonen, "Methods for evaluation of radiation from building materials," Radiat. Prot. Dosim., vol. 1, pp. 235 -238, 1985. 

[2] ICRP, Production of the public in situations of prolonged Radiation Exposure: Publication 82 Elsevier Science B.V., 1999. 

[3] E. Stranden, "Assessment of the Radiological Impact by Fly Ash in cement," Health Phys., vol. 45, p. 145, 1983. 

[4] J. Somlai, "Radiological aspects of the usability of red mud as building material additive," Journal of Hazardous Materials, vol. 150, 

p. 541, 2008. 

[5] UNSCEAR, "United nations scientific on the effects of atomic radiation. Sources, effects and risks of Ionizing radiation," Report is 

the General Assembly in the Annex B. Natural Sources of Radiation. United Nations, New York 1977. 

[6] C. J. Chen and Y. M. Lin, "Assessment of building materials from compliance with regulations of Roc," Environ. Internat., vol. 22, 

pp. S221 – S 226, 1996. 

[7] S. Y. U. Stoulos, M. Manolopoulou, and C. Papastefanou, "Assessment of natural radiation exposure and radon exhalation in 

building materials in Greece," J. Envrion. Radioact., vol. 69, pp. 225-240, 2003. 

[8] S. Righi and L. Bruzzi, "Natural radioactivity and radon exhalation in building materials used in Italian dwellings," J. Environ. 

Radioact., vol. 88, pp. 158-170, 2006. 

[9] F. O. Brigido, E. A. Montalvan, S. R. Rosa, Z. J. Tomas, and P. A. Hemandez, "Natural radio nuclides content in building materials 

and Gamma dose rate in Dwellings in Cuba," J. Environ Radioact., vol. 99, pp. 1834 -1 1837, 2008. 

[10] N. K. Ahmed, "Measurement of natural radioactivity in building materials in Qena city, Upper Egypt," Environ Radiact., vol. 83, pp. 

91-99, 2005. 

[11] UNSCEAR, United Nations scientific on the effects of atomic radiations. Sources, and effects of Ionizing radiation. United Nations, 

New York, 1977; 1993; 2000. 

[12] D. I. Jwanbot, Measurement of radioactivity levels in soil and food crop samples in mining areas on the Jos-Plateau. Nigeria: Lap 

Lambert Publishing House Germany, 2012. 

[13] N. N. Jibiri and S. T. U. Obarhua, "Indoor and outdoor Gamma dose rate exposure levels in major commercial building material 

distribution outlets and their radiological implication and occupant in Ibadan, Nigeria," Journal of Natural Sciences Research, vol. 3, 

pp. 25-31, 2013. 

 

 Table-1. The Range of Indoor and Outdoor Gamma Dose Rate Level at the Shops and Background Dose Rate Level 

S/N Types of 

building material 

Indoor (µSv/h) Outdoor (µSv/h)          

Background 

(µSv/h) 
Range Mean +SD Range Mean +SD 

1.  Floor tiles 0.234-0.226 0.23 + 0.01 0.215-0.206 0.21+0.01 0.127 

2.  Wall tiles 0.258-0.264 0.261+0.01 0.226-0.218 0.222+0.01 0.101 

3.  Wash hand basin 0.262-0.226 0.244+0.01 0.224-0.216 0.220+0.01 0.108 

4.  Cements   0.226-0.290 0.258+0.01 0.106 

5.  White cement 0.290-0.255 0.272+0.01 0.220-0.206 0.213+0.01 0.108 

6.  Paints 0.266-0.226 0.246+0.01 0.214-0.206 0.210+0.01 0.110 

7.  PVC ceiling 0.226-0.250 0.238+0.01 0.222-0.214 0.218+0.01 0.105 

8.  PVC Pipes 0.268-0.226 0.247+0.01 0.248-0.276 0.260+0.01 0.136 

9.  Iron rods   0.246-0.257 0.251+0.01 0.137 

 
Table-2. Annual indoor and outdoor effective gamma dose level 

S/N Building materials Indoor Dose (mSv) Outdoor (mSv) 

1 Floor tiles 0.977 ± 0.09 0.831±0.01 

2 Wall tiles 0.924 ± 0.04 0.823 ± 0.05 

3 Wash hand basin 0.913± 0.03 0.786 ± 0.04 

4 Cement No items displayed 0.816± 0.04 

5 White cement 0.804 ± 0.07 0.775 ± 0.01 

6 Paints 0.846 ± 0.03 0.876 ± 0.01 

7 PVC ceiling 0.827± 0.05 0.793 ± 0.01 

8 PVC pipes 0.808 ± 0.01 0.778± 0.03 

9 Iron rods No items displayed 0.621 ± 0.01 

 

 

 

 

 

 

 

 
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