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Journal of Environmental Radioactivity xxx (2010) 1e6

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Journal of Environmental Radioactivity

journal homepage: www.elsevier .com/locate/ jenvrad

Indoor and outdoor Radon concentration measurements in Sivas, Turkey,in comparison with geological setting

Metin Mihci a, Aydin Buyuksarac b,1, Attila Aydemir c,*, Nilgun Celebi d

a Iller Bankası, Etud Plan ve Yol Dairesi, Opera, 06053 Ankara, TurkeybCanakkale Onsekiz Mart University, Department of Geophysical Engineering, 17020, Canakkale, Turkeyc Turkiye Petrolleri A.O. Mustafa, Kemal Mah. 2. Cad. No: 86, 06100 Sogutozu, Ankara, TurkeydCekmece Nuclear Research and Training Centre (CNAEM), Cekmece, Istanbul, Turkey

a r t i c l e i n f o

Article history:Received 8 December 2009Received in revised form29 May 2010Accepted 18 June 2010Available online xxx

Keywords:Radon (222Rn)SivasCR-39 alpha-track detectorAlphameter

* Corresponding author. Tel.: þ(90) 312 207 2342;E-mail address: [email protected] (A. Aydemir)

1 Present address: Canakkale Onsekiz Mart Universical Engineering, Canakkale, Turkey.

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Please cite this article in press as: Mihci, M.,geological setting, J. Environ. Radioact. (201

a b s t r a c t

Indoor and soil gas Radon (222Rn) concentration measurements were accomplished in two stages in Sivas,a central eastern city in Turkey. In the first stage, CR-39 passive nuclear track detectors supplied by theTurkish Atomic Energy Authority (TAEA) were placed in the selected houses throughout Sivas centrum intwo seasons; summer and winter. Before the setup of detectors, a detailed questionnaire form wasdistributed to the inhabitants of selected houses to investigate construction parameters and properties ofthe houses, and living conditions of inhabitants. Detectors were collected back two months later andanalysed at TAEA laboratories to obtain indoor 222Rn gas concentration values. In the second stage, soil gas222Rn measurements were performed using an alphameter near the selected houses for the indoormeasurements. Although 222Rn concentrations in Sivaswere quite low in relationwith the allowable limits,they are higher than the average of Turkey. Indoor and soil gas 222Rn concentration distributionmapswereprepared seperately and thesemapswere appliedonto the surface geologicalmap. In thisway, both surveyswere correlated with the each other and they were interpreted in comparison with the answers of ques-tionnaire and the geological setting of the Sivas centrum and the vicinity.

� 2010 Elsevier Ltd. All rights reserved.

1. Introduction

Radon (222Rn) is a radioactive noble gas emitted by the decay of226Ra, an element of the 238U decay series. Radon-222 decays intoa series of other radioactive elements, of which 214Po and 218Po arethe most significant, as they contribute the majority of radiationdose when inhaled. Following a number of decay series, 218Potransforms into 210Po and it decays into stable 206Pb. The 222Rn andits decay products are reported as major causes of lung cancer(UNSCEAR, 2000a,b; ICRP, 1987), especially when they are inhaledattached to dust particles in the air. The 222Rn exists in soil andwater, and propagates into the atmosphere from these naturalsources. Meteorological parameters such as temperature, pressuredifferences, and humidity also affect indoor 222Rn concentrations.Levels of 222Rn can also be modified by the ventilation conditions,heatingecooling systems and the life style of inhabitants. Becauseof these factors and impact of 222Rn on the public health,

fax: þ(90) 312 286 9049..ity, Department of Geophys-

All rights reserved.

et al., Indoor and outdoor Rad0), doi:10.1016/j.jenvrad.2010

geophysical studies performing 222Rn concentrationmeasurementsare very important (Shirav and Vulkan, 1997; Wysocka et al., 2005).

There are many studies about the effects of geological andenvironmental factors on 222Rn measurements in a number ofother countries (Botkin and Keller, 1988; Harley and Harley, 1990;Hubbard and Swedjemark, 1991; Robinson and Sextro, 1995;Yamasaki and Lida, 1995; Vaupotic et al, 2003; Yu et al, 1995).Programmed indoor 222Rnmeasurements in Turkey were started in1984 by the Health Physics Department of the Cekmece NuclearResearch and Training Centre (CNAEM). Indoor surveys have beencompleted in 53 cities in the frame of this programme until 2007(Celebi and Ulug, 2002; Gurel and Cobanoglu, 1997; Koksal et al,1993; Ulug et al, 2004; Yarar et al, 2006), and the results aresummarised in Fig. 1.

2. Materials

2.1. Environmental conditions

Sivas city and the vicinity is mainly covered by Oligocene sabkha gypsum, LowerMiocene basal conglomerate, marine limestone and continental to marine clasticrocks, Middle Miocene playa gypsum levels with clastic intercalations, Pliocenefluvial clastic deposits and Quaternary unconsolidated alluvium. The climate in Sivasis continental climate. Although average temperature in winters is 0 �C, it may

on concentration measurements in Sivas, Turkey, in comparisonwith.06.013

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Fig. 1. Completed indoor measurements in Turkey by CNAEM (http://www.taek.gov.tr/tr/bilgi-kosesi/radyasyon-insan-ve-cevre/107-cevre-radyoaktivite-olcumleri/188-kapali-ortam-radon-degisimleri.html) Location of Sivas is illustrated in gray color.

Table 1Average indoor 222Rn concentrations in summer and winter measurements.

Season Number ofselectedhouses

Arithmetic avg.(Bq m�3)

Geometric avg.(Bq m�3)

Arithmeticstandarddeviation

Turkey’savg.(Bq m�3)

Summer 66 98 94 27.5 56Winter 32 89 86 24

M. Mihci et al. / Journal of Environmental Radioactivity xxx (2010) 1e62

decrease down to �36 �C from time to time. The temperature is <0� for 132 days onaverage. In the summer, the temperature is generally above 19 �C and it may reach38 �C. The difference of annual temperature between winter and summer is 74 �C.

2.2. Indoor radon measurements

The 222Rn gas concentration measurements in Sivas were performed in twostages (Mihci, 2008). In the first stage, CR-39 passive nuclear track detectors wereplaced into the selected houses in dwellings of Sivas to monitor the seasonal gas

0

2

4

6

8

18

16

14

12

10

9-0 -0229

4094- 96-06 08

8- 9 901-001 210-129 941-041

961-061 180-189

m/qB(noitartnecnoCnodaR3)

Nu

mb

er o

f B

uild

in

gs

remmuSretniW

Fig. 2. 222Rn measurements in summer and winter.

Please cite this article in press as: Mihci, M., et al., Indoor and outdoor Radgeological setting, J. Environ. Radioact. (2010), doi:10.1016/j.jenvrad.2010

concentration changes, in winter and summer times. In the second stage, soil 222Rngas measurements were accomplished using alphameters at the appropriate loca-tions outside of the selected indoor measurements.

This studywas accomplished in the summer andwinter of 2006. The CR-39 solidstate nuclear track detectors were contained in plastic dosimeters. The containerwas closed with a plastic cap in order to avoid dust deposition on the detector foils.

Table 2Maximum allowed 222Rn gas concentration limits (in Bq m�3) in Turkey and theworld.

Country Max. allowed222Rn(Bq m�3)



USA 150 India 150 Norway 200Germany 250 UK 200 Russia 200Australia 200 Ireland 200 Turkey 400China 200 Sweden 200 EU 400Denmark 400 Canada 800 ICRP 400France 400 Luxemburg 250 WHO 100


http://www.taek.gov.tr/tr/bilgi-kosesi/radyasyon-insan-ve-cevre/107-cevre-radyoaktivite-olcumleri/188-kapali-ortam-radon-degisimleri.html

http://www.taek.gov.tr/tr/bilgi-kosesi/radyasyon-insan-ve-cevre/107-cevre-radyoaktivite-olcumleri/188-kapali-ortam-radon-degisimleri.html

Fig. 3. Locations of indoor and soil gas 222Rn measurements applied onto the geological map.

Fig. 4. Surface geology and map of soil gas 222Rn concentration measurements. Contour Interval: 1 kBq m�3. Closed contours of high values are hatched.

Please cite this article in press as: Mihci, M., et al., Indoor and outdoor Radon concentration measurements in Sivas, Turkey, in comparisonwithgeological setting, J. Environ. Radioact. (2010), doi:10.1016/j.jenvrad.2010.06.013

Fig. 5. Surface geology and map of indoor 222Rn concentration measurements in summer. Contour Interval: 10 Bq m�3. Closed contours of high values are hatched.


These containers were distributed to 98 randomly selected houses, 66 of thedetectors were setup for the summer time measurements (from the end of May tobeginning of August) and 32 of them for winter (from mid-October to mid-December). Detectors were installed in the living rooms or bedrooms for a constantexposure period and collected at the same time. The selected roomswere located ondifferent floors, some of themwere at ground level and some of themwere upstairs.Before the setup of detectors, a questionnaire was distributed to the inhabitants ofselected houses and all questionnaires were returned to the authors of this study.The questionnaire included questions about the buildings such as construction date,construction material, existence of a cellar, building isolation status, ventilationconditions and heating system.

After 60 days exposure in each season, all detectors were collected and trans-ferred to the Cekmece Nuclear Research and Training Centre (CNAEM). In order todevelop tracks, CR-39 chips were immersed into 25% NaOH solution at 90 �C androtated slowly for 4 h. The development phase was followed by the track densitycounting with Radometer-2000 microscope unit connected to a computer withspecial analysis software and a Linux data base. The radioactivity concentration wascalculated using the conversion factor of 9 nSv/(Bq/h/m3), as suggested by UNSCEAR(2000a,b) (Koksal et al, 1993). Analysis results are presented in Fig. 2, comparingsummer and winter. Average (arithmetic and geometric) values and the arithmeticstandard deviations for the summer and winter time are presented in Table 1.

2.3. Soil gas 222Rn measurements

Soil gas 222Rn measurements were accomplished at 23 different localitiesoutside of the buildings where the indoor measurements were performed, only insummer time of 2006 in order to avoid or at least to minimize the possible


influences of themeteorology. An alphameter 611 produced by alphaNUCLEAR (with400-mm2 detector area and 65535-16 bit per 15min Counting Capacity) was set intoa 30-cm-deep hole with 51-mm diameter which was 5 m away from the building.The 222Rn concentration was recorded for 15 min together with the notes aboutcharacteristics of the ground such as geologic properties. This procedurewas done toexamine the correlation of the indoor and soil gas measurements and to investigatethe relationship between the ground radon risk and the housing system (includingconstruction material, determination of the settlement location, isolation andventilation systems etc.).

3. Results and discussions

Average 222Rn concentrations for both seasons were higher inSivas than the national average indoor value (56 Bqm�3) for Turkey(Yarar et al, 2006), although they were quite low in comparisonwith the maximum allowed 222Rn concentration limits, either forEU countries or for Turkey (Table 2). The 222Rn concentrations insummer were slightly higher than winter. This is related to theincrease of ground permeability after melting of thick snow layer inthe winter time which is common in this region. Summer timeindoor measurements were consistent with the soil gasmeasurements.

Indoor and soil gas 222Rn concentrations were mapped and thecontours were applied onto the surface geological map (Buyuksarac


Fig. 6. Surface geology and map of indoor 222Rn concentration measurements in winter. Contour Interval: 10 Bq m�3. Closed contours of high values are hatched.

0

02

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06

08

001

021

041

501-5555-5353-5252-5151-55-0Age of Building

Rad

on

C

on

c. (B

q/m

3

)

Fig. 7. Relationship between the 222Rn concentration and building age of selectedhouses.

M. Mihci et al. / Journal of Environmental Radioactivity xxx (2010) 1e6 5

et al., 2007) in order to investigate possible relationships. Fig. 3illustrates the locations of observation points distributed onto thegeological map. Initially, soil gas 222Rn values were applied onto thesurface geological map to observe if the 222Rn emission from theground was directly dependent on the geological units (Fig. 4).However, there was no significant dependence on the surfacegeology except for an increment of contour values at the boundarybetween alluvium and the geological unit composed of sandstone,siltstone and marl (Fig. 4). High 222Rn concentrations were rela-tively intensified on the alluvium covered area to the contrary ofexpectations for more porous and permeable units to the north andnorthwest of the city.

Seasonal distribution of indoor 222Rn concentrations were alsomapped onto the surface geological map, seperately for summer(Fig. 5) and for winter time (Fig. 6). Closed contours are focusedaround the boundary between the alluvium and more porous andpermeable units. There was another high concentration area on thealluviumvery close to the Kizilirmak River (Fig. 5). Although it is notso clear, 222Rn concentration increased towards the north andnorthwest, perhaps an artifact of insufficient sampling in this area.

On the contrary to the map of summer measurements, thewinter concentration map indicates an increment of contour values


to the north where the more porous and permeable units areexistent (Fig. 6). This could be related with the thick snow coveragein the winter creating a permeability barrier at the uppermostfrozen layers of alluvium which has already a limited permeability.Although, more porous and permeable formations to the north areexposed to the same weather conditions, excess of porosity andpermeability may allow extra 222Rn seepage relative to the allu-vium covered area.


0

02

04

06

08

001

021

041

061

02510150

Soil Radon Concentration (kBqm3-

)

In

do

or R

ad

on

C

on

c. (B

qm

-3)

Fig. 8. Comparison of indoor and soil gas 222Rn concentrations.


The construction materials of the houses were generallyconcrete and brick. Inhabitants in both seasons prefer naturalventilation in spite of usage of air conditioning (almost 100%), 94%of the houses observed in winter were regularly ventilated whileonly 86% of houses selected for summer were ventilated. Therewas no significant relationship between the 222Rn concentrationand building age of the selected houses: 222Rn concentrationdecreased considerably only for the buildings older than 55 years(Fig. 7).

Sivas can generally be classified in the low risk categorybecause of the low soil gas 222Rn concentration and there was nodirect relationship between the indoor and soil gas measurementresults (Fig. 8). Geological units have limited influence on theindoor concentrations. This study was focussed around thedowntown of Sivas and where there were relatively high 222Rnconcentrations on the alluvium covered area. However, moreporous and permeable units (sandstone, siltstone, conglomerate,etc.) are located to the north and northwest of the city. Althoughthere is no fault system reported in the study area, the boundarybetween alluvium and the geological units given above could bea fault related boundary, because it is apparently linear andregularly extended. Local soils may play a significant contributoryrole to soil gas and indoor 222Rn concentrations. Therefore,additional soil gas and indoor 222Rn measurements should beperformed with dense sampling intervals in these parts of thecity centre. In general, the sampling density used in Sivas wasnot sufficient for most 222Rn assessment tasks, all these obser-vations should be improved by expansion of the study areaperforming new measurements, especially through the north-eastern part of the city. In addition, only short term intra-soilradon measurements were accomplished in this study. Wesuggest short term and long term outdoor measurements(paralel to the intra-soil measurements) with the track detectorsto determine the local atmospheric levels (radon concentrationin the air).


Acknowledgement

This study is supported by the Cumhuriyet University, ScentificResearch Projects-Support Program, Project No: M-312. Authorswould like to thank the Cekmece Nuclear Research and TrainingCentre (CNAEM), Istanbul, Turkey for analyses of track detectors atits laboratories and their support to perform the Project. We wouldlike to extend our sincere thanks to Res. Assist. Dr. Ozcan Bektas toclassify the observed data and under graduate students; Mr. SinanKosaroglu, Mr. Cem Yucekas and Mr. M. Turgut Ezgo for setup ofdetectors into the selected houses and to collect them back. Authorsare also grateful to Mr. S.C. Sheppard, Editor-in-Chief of the Journalof Environmental Radioactivitiy and two anonymous reviewers fortheir constructive suggestions and critiques.

References

Botkin, D., Keller, E., 1988. Environmental Science. John Wiley & Sons, NY.Buyuksarac, A., Yilmaz, H., Bektas, O., Arisoy, M.O., 2007. Sivas Ili Deprem Duyarlik

ve Mikrobolgelendirme Projesi. DPT Bilimsel Arastirma Projesi. Sonuç Raporu(Project No: 2005. K.120220).

Celebi, N., Ulug, A., 2002. Alpha track technique for the determination of Rn anddecayproducts in air. In: Proceedings of 7th International Conference on NuclearAnalyticalMethods in the Life Sciences (NAMLS’7), Antalya, Turkey, pp.108e109.

Gurel, C., Cobanoglu, Z., 1997. Radon Kirliligi. Cevre Sagligi Temel Kaynak Dizisi.Saglik Bakanligi, Ankara.

Harley, N.H., Harley, J.H., 1990. Potential lung cancer risk from indoor radon expo-sure. CA Cancer J. Clin. 40, 265e275.

Hubbard, L., Swedjemark, G.A., 1991. Radon dynamics in Swedish dwellings:a status report. In: Proceedings of International Symposium on Radon andRadon Reduction Technology, Philadelphia, vol. 3. US Environmental ProtectionAgency, Research Triangle Park, NC Paper V-4.

International Commission on Radiation Protection (ICRP), 1987. Lung Cancer Riskfrom Indoor Exposure to Radon Daugthers Oxford. ICRP Publication. 50 17(1).

Koksal, M., Celebi, N., Ozcinar, B., 1993. Indoor radon concentrations in Istanbulhouses. Health Phys. 65, 87e88.

Mihci, M., 2008. Sivas merkez yerlesiminde radon gazi dagiliminin belirlenmesi veTurkiye’de yapilasma oncesi radon gazi olcumune yonelik yonetmelik taslagihazirlanmasi. M.Sc. Thesis, Cumhuriyet University, Turkey (unpublished), (inTurkish with English abstract).

Robinson, A.L., Sextro, R.G., 1995. The influence of a subslab gravel layer and openarea on soil-gas and radon entry into two experimental basements. HealthPhys. 69, 367e377.

Shirav, M., Vulkan, U., 1997. Mapping radon-prone areas: a geophysical approach.Environ. Geol. 31 (3/4).

Ulug, A., Karabulut, M.T., Celebi, N., 2004. Radon measurements with CR-39 trackdetectors at specific locations in Turkey. Nucl. Technol. Radiat. Prot. 19, 46e49.

UNSCEAR, 2000a. Sources and Effects of Ionizing Radiation. Report to the GeneralAssembly.

UNSCEAR, 2000b. Scientific Annexes, vol. I New York, United Nations.Vaupotic, J., Andjelov, M., Kobal, I., 2003. Relationship between radon concentra-

tions in indoor air and in soil gas. Environ. Geol. 42, 583e587.Wysocka, M., Kotyrba, A., Chalupnik, S., Skowronek, J., 2005. Geophysical methods

in radon risk studies. J. Environ. Radioact. 82, 351e362.Yamasaki, T., Lida, T., 1995. Measurements of thoron progeny concentration using

a potential alpha-energy monitor in Japan. Health Phys. 68, 840e844.Yarar, Y., Gunaydin, T., Celebi, N., 2006. Determination of radon concentrations of the

Dikili geothermal area in Western Turkey. Radiat. Prot. Dosimetry 118, 78e81.Yu, K.N., Chan, T.F., Young, E.C., 1995. The variation of radon exhalation rates from

building surfaces of different ages. Health Phys. 68, 716e718.


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