monitoring of 220 rn concentrations in buildings of kufa

Research ArticleMonitoring of 220Rn Concentrations in Buildings ofKufa Technical Institute Iraq

Ali Abid Abojassim Al-Hamidawi

Department of Physics Faculty of Science University of Kufa Box 221 Al-Najaf Kufa Iraq

Correspondence should be addressed to Ali Abid Abojassim Al-Hamidawi alialhameedawiuokufaeduiq

Received 7 November 2015 Revised 19 November 2015 Accepted 22 November 2015

Academic Editor Massimo Zucchetti

Copyright copy 2015 Ali Abid Abojassim Al-Hamidawi This is an open access article distributed under the Creative CommonsAttribution License which permits unrestricted use distribution and reproduction in any medium provided the original work isproperly cited

This paper presents the measurements of thoron and the progeny in fifteen buildings in Kufa Technical Institute Iraq from June2015 to April 2015 using RAD-7 detectors Also annual effective dose rate was calculated in all buildings under study The thoronconcentration varies from 0535 plusmn 058Bqm3 to 5350 plusmn 182Bqm3 with an average 1839 plusmn 418Bqm3 The concentration ofthoron daughters was found to vary from 014 mWL to 144mWL with an average 053 plusmn 011mWL The annual effective dosesdue to thoron mainly vary from 0042mSvy to 081mSvy with an average 020 plusmn 006mSvy The preliminary results in this studyindicate that they may be suitable for evaluating the indoor 220Rn and its progeny concentrations whenever the public exposure to220Rn and its progeny is taken into account During this survey the continuous difficulty in measuring thoron was also pointed outdue to its short half-life and faults in the measuring system

1 Introduction

Radon isotopes are chemically inert radioactive gases thatoccur in the environment as a result of the decay of radioac-tive elements in soil and minerals [1 2] Thoron (220Rn) isone of three naturally occurring radon isotopes which resultsfrom the decay of thorium 232Thseries It has a half-life equalto 55 seconds In indoor environments the air mixing timeis usually much larger than the half-life of 220Rn the 220Rnconcentration is highly nonuniform so it is difficult to obtaina representative value of indoor 220Rn concentrations [3]Moreover from the view of dose contribution 220Rn progenyis much more important than 220RnTherefore it is desirableto know the concentrations of 220Rn progenyThoron can stillbe a hazard since its progeny 212Pbwith a half-life of 106 h canaccumulate to significant levels in breathable air [4]Themainsource of the indoor thoron concentration is the surroundingbuilding material In the traditional dwellings this is the baresoil floor either soil in cave dwellings or unburned adobebricks and unplastered stone in aboveground dwellings Itis assumed that the inhalation dose to the human beingsfrom thoron and its progeny is negligible although recent

studies in many countries have revealed that this may not beentirely correct [5] Thoron and its progeny contribute littleto the radiation dose in normal background region due toits small half-life Increased concentrations of thoron (220Rn)were recently measured in residential traditional dwellingsin China [6ndash8] India [9 10] and Iraq [11] The aim of thepresent work is to determine the thoron concentration inbuildings of Kufa Technical Institute using RAD-7 (radonmonitoring system) of Durridge Company (USA) AlsoThoron progeny (in mWL) and annual effective dose (inmSvy) were calculated using standard equations found inICRP and UNSCEAR

2 Study Area

Kufa Technical Institutewas established in 1980 with locationof latitude 32∘310158403410158401015840N and longitude 44∘2410158401810158401015840E with a totalarea 268035m2 [12] shown in Figure 1

The institute includes nearly fifteen buildings which arePharmacy Department dwelling Cars Department work-shops Student Housing Analyses Departments incubationElectricity Department Deanship of Institute Deanship of

Hindawi Publishing CorporationScience and Technology of Nuclear InstallationsVolume 2015 Article ID 738019 5 pageshttpdxdoiorg1011552015738019

2 Science and Technology of Nuclear Installations

Table 1 Sites of measurements in studied area for taking samples

No Name of Building Code of Building CoordinatesLat (deg) Long (deg)

1 Pharmacy Department B1 44∘401015840480410158401015840N 32∘051015840699310158401015840E2 Dwelling B2 44∘401015840452210158401015840N 32∘051015840922910158401015840E3 Cars of Department B3 44∘401015840587810158401015840N 32∘051015840728610158401015840E4 workshops B4 44∘401015840608910158401015840N 32∘051015840755210158401015840E5 Student Housing B5 44∘401015840416110158401015840N 32∘051015840919310158401015840E6 Analyses Departments B6 44∘401015840470610158401015840N 32∘051015840725810158401015840E7 Incubation B7 44∘401015840445110158401015840N 32∘051015840837310158401015840E8 Electricity Department B8 44∘401015840507910158401015840N 32∘051015840730210158401015840E9 Deanship of Institute B9 44∘401015840590410158401015840N 32∘051015840787810158401015840E10 Deanship of Healthy Technical B10 44∘401015840461510158401015840N 32∘051015840805010158401015840E11 School B11 44∘401015840574910158401015840N 32∘061015840035310158401015840E12 Agricultural Department B12 44∘401015840531310158401015840N 32∘051015840966710158401015840E13 Mechanics of Department B13 44∘401015840572610158401015840N 32∘051015840743610158401015840E14 Nursing Department B14 44∘401015840471310158401015840N 32∘051015840906710158401015840E15 Community Health Department B15 44∘401015840470610158401015840N 32∘051015840725810158401015840E

Figure 1 Map of Kufa Technical Institute

Healthy Technical Department school Faculty of Agri-culture Mechanics Department Nursing Department andCommunity Health Department The study area was chosenfor the following reasons these buildings are easy to accessand it is easy to deal with educated people and that will reducethe losses in distributed detectors it is easy to distributeand collect detectors in governmental buildings compared toother places these buildings are highly populated by peoplewho spend long time in the buildings and these buildings arelocated in the center of Najaf Governorate and form a largeportion of Najaf city

3 Materials and Methods

This title includes important steps (materials and methods)for measuring the thoron concentrations in building under

Air outletAir inletwith filter

Pump

Readout

Detector

Measurement chamber

Figure 2 Measurement chamber of the RAD-7 detector [13]

study location and collection of the samples experimentalsetup and calculation of all the thoron progeny and theannual effective dose

31 Location and Collection of the Samples In the presentstudy 15 buildings were chosen as fair distribution in KufaTechnical Institute The buildings were determined usingGPS as shown in Table 1 Table 1 showed the sites of measure-ment in studied area for taking samples designed accordingto name of building code of building and coordinates

32 Experimental Setup for Measurement of Thoron Con-centration The RAD-7 internal sample cell is a 07 dm3conducting hemisphere with a 2200V potential relative to thedetector that is placed at the center of the hemisphere (seeFigure 2)

Science and Technology of Nuclear Installations 3

Thoron samplingpoint

Small dryingtube

516998400998400 to 316998400998400

reducer

Air flow

Air flow

2998400998400 L 516998400998400 ID

316998400998400 to 18998400998400 reducer

Inlet filter

RAD-7 (thoron protocol)

316998400998400 to 18998400998400 reducer

Air outputExternal power

2998400998400 L 18998400998400 ID

2998400998400 L 18998400998400 ID

36998400998400 L 316998400998400 ID

Figure 3 Experimental setup for operating the counting system for thoron measurements

The detector operates in external relative humidity rang-ing from0 to 95 and internal humidities of 0 to 10withthe low detection threshold of 4 Bqm3 and an upper lineardetection limit of 400 kBqm3 The detector was calibratedwith an accuracy of 5 RAD-7 separates 222Rn and 220Rnsignals by their progeniesrsquo unique 120572-particle energies withlittle cross interference which means that it counts twoisotopes at the same time [13] RAD-7 responds virtuallyinstantly to the presence of thoron Its time constant for theresponse to thoron is less than 1min As mentioned abovethe RAD-7 calculates thoron concentration on the basis ofthe count rate in the alpha line of 216Po (energy 678MeV)the first decay product of thoron gas Thoron calibrationprecision is plusmn25 The measurements were done using theldquothoron protocolrdquo with a 5 or 30min repeating cycle [13]For each thoron concentration the experiment was repeatedabout 24 times (one day) Figure 3 shows experimental setupof RAD-7 detector for measuring thoron concentration

33 Calculation ofThoron Progeny Concentration and AnnualEffective Dose The thoron progeny levels or PAEC values (inmWL) were calculated by using the equation [14 15]

PAEC (mWL) =119862119879times 119865119879

37 (1)

where 119865119879is equilibrium factor for thoron having the value

(01) [16]The annual effective doses due to the exposure to thoron

and progeny in the building of study area were calculated bythe formula [17]

Annual effective dose(mSvy)

= 119862119879(Bqm3) times 119865 times 119905 (h)

times 119863 (nSvh) per (Bqm3)

(2)

where 119862119879is the measured thoron concentration (in Bqmminus3)

119865 is the average of equilibrium factor for thoron and progeny[18] 119905 is the indoor occupancy time (in dwelling = 7000 hybut in other buildings = 2190 hy) and 119863 is the doseconversion factor which converts activity concentration toeffective dose rate119863 = 40 nSvh per Bqm3

34 Statistical Evaluation Statistical analysis for evaluationof the results was done by calculating arithmetic meanand standard deviation for thoron concentrations thoronprogeny concentrations and annual effective dose measure-ments All these measurements had been done for all samplesunder study Results were expressed as mean plusmn standarddeviation for each building The results were evaluated byStudentrsquos unpaired 119905-tests

4 Results and Discussion

The aim of the studies has been to find an approximatemean and range of thoron concentrations thoron progenyand annual effective dose in buildings in order to assess thepossible health hazards from thoron indoors in buildings ofKufaTechnical Institute Iraq Table 2 represents themeasure-ment of the mean thoron concentrations values plusmn standarddeviation (SD) in Bqm3 in buildings of Kufa TechnicalInstituteThe value of thoron concentration varies from 0535to 5350 Bqm3 with an average of 1839 plusmn 418Bqm3 Alsofrom Table 2 it is found that for some of the buildingssuch as B13 B14 and B15 thoron concentrations do notappear because the value of thoron concentrations is lessthan value of detection limit which is equal to 4 Bqm3 [13]Figure 4 shows the percentage of thoron concentrations in allbuildings under study Table 3 and Figure 5 show the meanvalues of thoron progeny concentrations and the annualeffective dose in building under study which was calculatedfor each sample using (1) and (2) respectively The thoron


Table 2 Results of thoron concentrations in study area

No CodeBuilding

Average of ThoronConcentrations in

(Bqm3)1 B1 5350 plusmn 1822 B2 3210 plusmn 1413 B3 2140 plusmn 1164 B4 1873 plusmn 1105 B5 1783 plusmn 1056 B6 1680 plusmn 1027 B7 1426 plusmn 0818 B8 1204 plusmn 0879 B9 1068 plusmn 04110 B10 1003 plusmn 07911 B11 0803 plusmn 07112 B12 0535 plusmn 05813 B13 BDL14 B14 BDL15 B15 BDL

Average plusmn SD 1839 plusmn 418

B124

B215

B310B4

8

B58

B68

B76

B85

B95

B105

B114

B122

B13BLD

B14BLD

B15BLD

Figure 4 The percentage of the thoron concentrations in all build-ings of Kufa Technical Institute

progeny concentrations in the buildings under study variedfrom 014 to 144mWL with an average of 053 plusmn 011mWLwhile the annual effective dose received by the inhabitantsin the buildings under study varied from 004 to 042mSvywith an average of 020plusmn006mSvyThe results vary becausedifferent factors determine indoor thoron concentrationssuch as the different building material and ventilation rateand one important factor is the geology The results of

Table 3 Results of thoron progeny concentration and annualeffective dose in study area

No CodeBuilding

PAEC(mWL)

Annual effectivedose (mSvy)

1 B1 144 0422 B2 086 0813 B3 057 0164 B4 051 0155 B5 048 0146 B6 045 0137 B7 038 0118 B8 032 0099 B9 028 00810 B10 027 00711 B11 021 00612 B12 014 00413 B13 mdash mdash14 B14 mdash mdash15 B15 mdash mdash

Average plusmn SD 053 plusmn 011 020 plusmn 006

Annual effective dose (mSvy)

B2B1 B3 B4 B5 B6 B7 B8 B9 B10

B11

B12

B13

B14

B15

Code buildingsPAEC (mWL)BL

DBL

DBL

DFigure 5 Results of thoron progeny concentrations and the annualeffective dose in building under study

thoron concentrations thoron progeny concentrations andthe annual effective dose are lower than the safe limitsrecommended by ICRP 1993 and ICRP 2011 [14 19] Theaverage of thoron concentration obtained in this study wascompared with other similar studies in literature and this ispresented in Table 4

5 Conclusion

Indoor thoron concentrations thoron progeny concentra-tions and annual effective dose received by the general publichave been determined for the selected residences of buildingsin Kufa Technical Institute and found under the safe limit laiddown by ICRP and UNSCEAR Present study concludes that


Table 4 Comparison of thoron concentration rate of the present study with other studies of the different countries

Number Country Average of thoron concentrations (Bqm3) References1 Romania 53 [20]2 India 106 144 [21 22]3 Iran 34 [23]4 Present study 1839 mdash

the buildings are safe without posing significant radiologicalthreat to the human beings

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

References

[1] E Giargoni A Honing and A Rottger ldquoDevelopment of acalibration facility for measurements of the thoron activityconcentrationrdquo Nuclear Instruments and Methods in PhysicsResearch Section A Accelerators Spectrometers Detectors andAssociated Equipment vol 506 no 1-2 pp 166ndash172 2003

[2] L Mjones R Falk H Mellander and L Nyblom ldquoMeasure-ments of thoron and thoron progeny indoors in SwedenrdquoRadiation Protection Dosimetry vol 45 no 1ndash4 pp 349ndash3521992

[3] W Zhuo T Iida and X Yang ldquoEnvironmental radon andthoron progeny concentrations in Fujian province of ChinardquoRadiation Protection Dosimetry vol 87 no 2 pp 137ndash140 2000

[4] J Chen D Moir T Pronk T Goodwin M Janik and STokonami ldquoAn update on thoron exposure in Canada withsimultaneous 222Rn and 220Rnmeasurements in fredericton andhalifaxrdquo Radiation Protection Dosimetry vol 147 no 4 pp 541ndash547 2011

[5] F SteinhauslerW Hofmann andH Lettner ldquoThoron exposureofman a negligible issue 1st IntWorkshop Rimini Italy 276ndash2793rdquoRadiation ProtectionDosimetry vol 56 pp 127ndash131 1994

[6] J Tschiersch andM Musch ldquoRadon exposures in homes is thecontribution of 220Rn (Thoron) to dose always negligiblerdquo inProceedings of the 9th International Conference on Health EffectsIncorporated Radionuclides (HEIR rsquo04) U Oeh P Roth and HG Paretzke Eds GSF-Bericht 0605 pp 214ndash220 NeuherbergGermany 2005

[7] B Shang B Chen Y Gao Y Wang H Cui and Z Li ldquoThoronlevels in traditional Chinese residential dwellingsrdquo Radiationand Environmental Biophysics vol 44 no 3 pp 193ndash199 2005

[8] L Zhang J Wu Q Guo andW Zhuo ldquoMeasurement of thorongas in the environment using a Lucas scintillation cellrdquo Journalof Radiological Protection vol 30 no 3 pp 597ndash605 2010

[9] M Sreenath Reddy P Yadagiri Reddy K Rama Reddy K PEappen T V Ramachandran and Y S Mayya ldquoThoron levelsin the dwellings of Hyderabad city Andhra Pradesh IndiardquoJournal of Environmental Radioactivity vol 73 no 1 pp 21ndash282004

[10] L A Sathish H C Ramanna K Nagaraja and S SundareshanldquoDistribution of indoor thoron and its progeny levels in adwellingrdquo Arabian Journal for Science and Engineering vol 35pp 209ndash218 2010

[11] A A AbojassimRadon and thoron concentrationsmeasurementin Al-Najaf and Al-Kufa area [PhD thesis] Baghdad UniversityCollege Sciences 2013

[12] T Ring International Dictionary of Historic Places Middle Eastand Africa Taylor amp Francis 1996

[13] Durridge Company Reference Manual Version 601 RAD-7Electronic Radon Detector Durridge Company Billerica MassUSA 2010

[14] International Commission on Radiological Protection (ICRP)ICRP Publication No 65 Pergamon Press Oxford UK 1993

[15] M S Khan and A Azam ldquoDepth dependent study of radonthoron and their progeny in tube-wellsrdquo Journal of Radioana-lytical and Nuclear Chemistry vol 294 no 2 pp 289ndash293 2012

[16] UNSCEAR United Nation Scientific Committee on the Effectsof Atomic Radiation Sources and Effects of Ionizing RadiationUnited Nations New York NY USA 1999

[17] United Nation Scientific Committee on the Effect of AtomicRadiation (UNSCEAR) Exposures from Natural RadiationSources (Report to General Assembly Annex B) 2000

[18] ICRP Limits for Inhalation of RadonDaughters byWorkers ICRPPublication 32 Annals of the ICRP6 (1) PergamonPressOxfordUK 1981

[19] ICRP International Commission on Radiological ProtectionICPR Publication-113 Pergamon Press Oxford UK 2011

[20] B Burghele andCCosma ldquoComparison between radon passiveand active measurements and problems related to thoronmeasurementsrdquo Romanian Journal of Physics vol 58 pp 56ndash612013

[21] A Sharmaa A K Mahur S Asad Ali R G Sonkawade andA C Sharma ldquoMonitoring of indoor radon thoron levels andannual effective dose in some dwelling of Jaipur RajasthanIndia using double dosimeter cupsrdquo Archives of Applied ScienceResearch vol 7 no 2 pp 1ndash4 2015

[22] V Mehta S P Singh R P Chauhan and G S MudaharldquoMeasurement of indoor radon thoron and their progeny levelsin dwellings of Ambala district Haryana northern India usingsolid state nuclear track detectorsrdquoRomanian Journal of Physicsvol 59 no 7-8 pp 834ndash845 2014

[23] Y Fakhri A H Mahvi G Langarizadeh et al ldquoConcentrationof radon (Radon 222 andThoron) in indoor air decorative stoneof warehouses and the effective dose by staffMinab Iranrdquo IOSRJournal of Environmental Science vol 9 no 3 pp 62ndash67 2015

TribologyAdvances in

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

FuelsJournal of


Journal ofPetroleum Engineering


Industrial EngineeringJournal of


Power ElectronicsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in

CombustionJournal of


Journal of


Renewable Energy

Submit your manuscripts athttpwwwhindawicom


StructuresJournal of


RotatingMachinery


EnergyJournal of


Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal ofPhotoenergy


Nuclear InstallationsScience and Technology of


Solar EnergyJournal of


Wind EnergyJournal of


Nuclear EnergyInternational Journal of


High Energy PhysicsAdvances in

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014


Table 1 Sites of measurements in studied area for taking samples

No Name of Building Code of Building CoordinatesLat (deg) Long (deg)

1 Pharmacy Department B1 44∘401015840480410158401015840N 32∘051015840699310158401015840E2 Dwelling B2 44∘401015840452210158401015840N 32∘051015840922910158401015840E3 Cars of Department B3 44∘401015840587810158401015840N 32∘051015840728610158401015840E4 workshops B4 44∘401015840608910158401015840N 32∘051015840755210158401015840E5 Student Housing B5 44∘401015840416110158401015840N 32∘051015840919310158401015840E6 Analyses Departments B6 44∘401015840470610158401015840N 32∘051015840725810158401015840E7 Incubation B7 44∘401015840445110158401015840N 32∘051015840837310158401015840E8 Electricity Department B8 44∘401015840507910158401015840N 32∘051015840730210158401015840E9 Deanship of Institute B9 44∘401015840590410158401015840N 32∘051015840787810158401015840E10 Deanship of Healthy Technical B10 44∘401015840461510158401015840N 32∘051015840805010158401015840E11 School B11 44∘401015840574910158401015840N 32∘061015840035310158401015840E12 Agricultural Department B12 44∘401015840531310158401015840N 32∘051015840966710158401015840E13 Mechanics of Department B13 44∘401015840572610158401015840N 32∘051015840743610158401015840E14 Nursing Department B14 44∘401015840471310158401015840N 32∘051015840906710158401015840E15 Community Health Department B15 44∘401015840470610158401015840N 32∘051015840725810158401015840E

Figure 1 Map of Kufa Technical Institute

Healthy Technical Department school Faculty of Agri-culture Mechanics Department Nursing Department andCommunity Health Department The study area was chosenfor the following reasons these buildings are easy to accessand it is easy to deal with educated people and that will reducethe losses in distributed detectors it is easy to distributeand collect detectors in governmental buildings compared toother places these buildings are highly populated by peoplewho spend long time in the buildings and these buildings arelocated in the center of Najaf Governorate and form a largeportion of Najaf city

3 Materials and Methods

This title includes important steps (materials and methods)for measuring the thoron concentrations in building under

Air outletAir inletwith filter

Pump

Readout

Detector

Measurement chamber

Figure 2 Measurement chamber of the RAD-7 detector [13]

study location and collection of the samples experimentalsetup and calculation of all the thoron progeny and theannual effective dose

31 Location and Collection of the Samples In the presentstudy 15 buildings were chosen as fair distribution in KufaTechnical Institute The buildings were determined usingGPS as shown in Table 1 Table 1 showed the sites of measure-ment in studied area for taking samples designed accordingto name of building code of building and coordinates

32 Experimental Setup for Measurement of Thoron Con-centration The RAD-7 internal sample cell is a 07 dm3conducting hemisphere with a 2200V potential relative to thedetector that is placed at the center of the hemisphere (seeFigure 2)



Small dryingtube

516998400998400 to 316998400998400

reducer

Air flow

Air flow

2998400998400 L 516998400998400 ID

316998400998400 to 18998400998400 reducer

Inlet filter


316998400998400 to 18998400998400 reducer


2998400998400 L 18998400998400 ID

2998400998400 L 18998400998400 ID

36998400998400 L 316998400998400 ID




PAEC (mWL) =119862119879times 119865119879

37 (1)





= 119862119879(Bqm3) times 119865 times 119905 (h)


(2)








No CodeBuilding




B124

B215

B310B4

8

B58

B68

B76

B85

B95

B105

B114

B122

B13BLD

B14BLD

B15BLD




No CodeBuilding

PAEC(mWL)





B2B1 B3 B4 B5 B6 B7 B8 B9 B10

B11

B12

B13

B14

B15


DBL

DBL



5 Conclusion








References




























FuelsJournal of







Advances in



Journal of


Renewable Energy





RotatingMachinery


EnergyJournal of



















Small dryingtube

516998400998400 to 316998400998400

reducer

Air flow

Air flow

2998400998400 L 516998400998400 ID

316998400998400 to 18998400998400 reducer

Inlet filter


316998400998400 to 18998400998400 reducer


2998400998400 L 18998400998400 ID

2998400998400 L 18998400998400 ID

36998400998400 L 316998400998400 ID




PAEC (mWL) =119862119879times 119865119879

37 (1)





= 119862119879(Bqm3) times 119865 times 119905 (h)


(2)








No CodeBuilding




B124

B215

B310B4

8

B58

B68

B76

B85

B95

B105

B114

B122

B13BLD

B14BLD

B15BLD




No CodeBuilding

PAEC(mWL)





B2B1 B3 B4 B5 B6 B7 B8 B9 B10

B11

B12

B13

B14

B15


DBL

DBL



5 Conclusion








References




























FuelsJournal of







Advances in



Journal of


Renewable Energy





RotatingMachinery


EnergyJournal of



















No CodeBuilding




B124

B215

B310B4

8

B58

B68

B76

B85

B95

B105

B114

B122

B13BLD

B14BLD

B15BLD




No CodeBuilding

PAEC(mWL)





B2B1 B3 B4 B5 B6 B7 B8 B9 B10

B11

B12

B13

B14

B15


DBL

DBL



5 Conclusion








References




























FuelsJournal of







Advances in



Journal of


Renewable Energy





RotatingMachinery


EnergyJournal of























References




























FuelsJournal of







Advances in



Journal of


Renewable Energy





RotatingMachinery


EnergyJournal of





















FuelsJournal of







Advances in



Journal of


Renewable Energy





RotatingMachinery


EnergyJournal of

















monitoring of 220 rn concentrations in buildings of kufa

Documents