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Evaluation of excess life time cancer risk fromgamma dose rates in Jhelum valley

Muhammad Rafique a,*, Saeed Ur Rahman b, Muhammad Basharat c,Wajid Aziz d, Iftikhar Ahmad e, Khursheed Ahmed Lone f, Khalil Ahmad g,Matiullah h

aDepartment of Physics, University of Azad Jammu & Kashmir, Muzaffarbad 13100, Azad Kashmir, PakistanbDepartment of Medical Physics, Nuclear Medicine, Oncology and Radiotherapy Institute, Islamabad, Pakistanc Institute of Geology, University of Azad Jammu & Kashmir, Muzaffarbad 13100, Azad Kashmir, PakistandDepartment of Computer Sciences and Information Technology, University of Azad Kashmir, 13100 Azad Kashmir,

PakistaneDepartment of Mathematics, University of Azad Jammu and Kashmir, Muzaffarbad 13100, Azad Kashmir,

PakistanfConsultant Medical Oncologist, Abbas Institute of Medical Sciences, Muzaffarabad, PakistangRadiation Dosimetry Laboratory, Health Physics Division, PINSTECH, Nilore, Islamabad, PakistanhDirectorate of Systems and Services, PINSTECH, Nilore, Islamabad, Pakistan

a r t i c l e i n f o

Article history:

Received 4 November 2013

Accepted 24 November 2013

Keywords:

Back ground radiation

Ambient outdoor gamma dose rates

Lithology

Excess life time cancer risk

* Corresponding author.E-mail addresses: mrafique@gmail.com,

Peer review under responsibility of The Egy

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1687-8507/$e see frontmatterCopyrightª 2014,TheEg

http://dx.doi.org/10.1016/j.jrras.2013.11.005

a b s t r a c t

Human beings are continuously exposed to the radiations coming from outside and inside

their bodies. Outside and inside radiations are coming from ground, building materials,

food, air, the universe and even elements within human own bodies. According to

UNSCEAR 2000 report, background radiations deliver an average effective dose of 2.4 mSv

per person worldwide. Sustained exposure from high background radiation levels may

pose substantial health threats to general public. In the current study we are presenting the

results of ambient outdoor gamma dose rates measured for Jhelum valley of the state of

Azad Kashmir. This study has been carried out by using Ludlum micrometer-19 which is an

active and portable detector. Effects of different parameters of interest on the measured

values of gamma dose rates have been investigated. For the region under investigation,

minimum and maximum indoor gamma dose rates were found as 610 � 4.05 mGy$y�1 and

1372 � 2.7 mGy$y�1, respectively, whilst minimum and maximum outdoor gamma dose

rates were found as 495 � 4.49 mGy$y�1 and 1296 � 2.78 mGy$y�1, respectively. Overall

arithmetic mean (A.M) and geometric mean (G.M) values of gamma dose rates for indoor

and outdoor measurements were found as 940 � 3.26 mGy$y�1, 892 � 3.35 mGy$y�1 and

928 � 3.28 mGy$y�1, 880 � 3.37 mGy$y�1 respectively. Excess life time cancer risk (ELCR) for

mrafique@ajku.edu.pk, rafi_722002@yahoo.com (M. Rafique).

ptian Society of Radiation Sciences and Applications

evier

yptianSocietyofRadiationSciencesandApplications. ProductionandhostingbyElsevier B.V.All rights reserved.

J o u r n a l o f R a d i a t i o n R e s e a r c h and A p p l i e d S c i e n c e s 7 ( 2 0 1 4 ) 2 9e3 530

indoor exposure ranges from 1.057 � 10�3 to 2.377 � 10�3 with an average value of

1.629 � 10�3. For outdoor exposure, ELCR varies from 0.352 � 10�3 to 0.792 � 10�3 with mean

value of 0.543 � 10�3. Average values of indoor gamma doses were found to be greater than

the world population-weighted average for indoor gamma dose rates (780 mGy$y�1 or

89 nGy h�1).

Copyright ª 2014, The Egyptian Society of Radiation Sciences and Applications. Production

and hosting by Elsevier B.V. All rights reserved.

1. Introduction

At present, studies on health effects due to ionizing radiations

have produced substantial evidences that exposure to high

level of radiations can cause illness or even death. Despite a

well known effect of cancer, scientists have long known that

ionizing radiations with high doses may also cause mental

retardations in the children’s of mothers exposed to radia-

tions during pregnancy period. High radiation doses are also

cause of other health effects as mentioned in NRC (BEIR VII

Phase 2, 2006) report that data from atomic bomb survivors

shows that there is connection of high radiation doses with

heart disease and strokes. The National Research Council 1999

report (BEIR VI) suggests a range of 1e10mSvwithmean value

of 2.4 mSv for average annual exposure worldwide from nat-

ural sources including high and low LET. Main source of these

back ground radiations is radon and its progenies, contrib-

uting 1.2 mSv per year (NRC, BEIR VII Phase 2, 2006).

After radon next highest percentage of background radia-

tions comes from Cosmic and terrestrial sources respectively.

Terrestrial radiations’ coming from rocks and soils (contain-

ing radionuclides of different concentrations) varies depend-

ing upon geographical locations. Terrestrial radiations also

contribute significant part to total exposure due to back-

ground radiations (BEIR VI 1999).

Several epidemiological studies and radiation surveys

conducted on atomic bomb survivors in Hiroshima and

Nagasaki served as principal role for the development of

cancer risk estimates. During past many decades many sci-

entists have conducted different studies for monitoring and

risk assessment of radiation exposure (Chikasawa, Ishii, &

Sugiyama, 2001; Clouvas, Xanthos, & Antonopoulos-Domis,

2004; Duggal, Rani, Mehra, & Ramola, 2013; Erees, Akozcan,

Parlak, & Cam, 2006; Hewamanna, & Sumithrarachchi, 2001;

Kovacs, Szeiler, Fabian, Kardos, Gregori�c & Vaupoti�c 2013;

Matiullah, Fariha, & Rafique 2012; Rafique, 2013; Rafique,

Basharat, Azhar Saeed & Rahman, 2013; Rafique, Rehman,

Matiullah, Malik, Rajput, Rahman, & Rathore, 2011; Rahman,

Matiullah, Malik, Rafique, Anwar, Ziafat, & Jabbar 2011; Rah-

man & Rafique 2012; Rahman, Rafique, Jabbar & Matiullah

2013). They have preliminary monitored the radiation doses

and then tried to develop different mathematical models in

order to estimate the level of risk factor. In current study we

have monitored gamma dose rates while dividing the whole

area of study in to three Zones. namely, 1) Kakerwara

(Zone#1), 2) Lawasi (Zone#2) and 3) Hattian Duppatta (Zone#3).

Major radionuclide’s contributing gamma dose rates in the

studied area are 137Cs, 226Ra, 232Th and 40K. In a recent study

conducted in Leepa valley (Rafique, Jabbar, et al., 2013) which

is the part of Jhelumvalley the activity concentrations of 137Cs,226Ra, 232Th and 40K in the soil samples were found as

15.04 � 0.29, 31.25 � 0.46, 44.1 � 1.07 and 575 � 8.89 Bq kg�1

respectively. This study will help us to set a baseline data for

radiation levels and from obtained data we shall calculate

excess life time cancer risk (ELCR) for inhabitants of the area.

2. Material and method

A GPS based gamma survey was conducted using a portable

radiometric instrument, Ludlum micrometer 19 (manufac-

tured by Ludlum measurements Inc). It is used for low level

micro R gamma surveys and consists of 100�1

00(2.5 � 2.5 cm)

(Dia x L) NaI (TI) scintillator (http://www.drct.com/dss/

INSTRUMENTATION/Ludlum/Ludlum-Model-19.htm). Its

sensitivity is 175 cpm/mR/h (17,500 cpm/mSv/h), based upon

Cs-137 gamma. The detector has energy dependent response.

Gamma dose rates were measured at the distance of one

meter above the ground. For each location twomeasurements

spanning over 2 min were carried out and these measure-

ments were than averaged to single value. Data obtained for

the external exposure rate in mR/h was converted into absor-

bed dose rate mGy/y using the conversion factor:

1 mR=h ¼ 8:7 nGy=h ¼ 8:7� 10�3 mGy=ð1=8760 yÞ

¼ 8:7� 10�3 mGyð1=8760 yÞ ¼ 76:212 mGy y�1:

The readings are presented in terms of mGy/y as well as in

nGy/h.

3. Geological setting of the area

The Hazara Kashmir Syntaxis (HKS) is the prominent struc-

tural feature in the northwest Himalayas, Pakistan. It is built

up of a Precambrian to Tertiary rocks which are imbricated

and folded (Baig & Lawrence, 1987; Bossart, Dietrich, Greco,

Ottiger & Ramsay; 1988; Greco 1991; Wadia 1931: Fig. 1a). The

core of the syntaxis consists of red beds of sandstone,

mudstone, shale and claystone of earlyMiocene age belonging

to the Murree Formation. The western limb of HKS is trun-

cated by Jhleum Fault (JF) and Muzaffarabad Fault (MF) (Baig &

Lawrance, 1987). The active Muzaffarabad Fault is the major

fault run in the study area (Fig. 1b). The rocks of the area are

intensely deformed due to Himalayan orogeny. The Muzaf-

farabad Fault runs entirely within the Murree Formation

Fig. 1 e (a) Inset map shows the structural feature of Hazara

Kashmir Syntaxis in NW Himalayas, Pakistan. (b) Map

shows the geological units within study area (compiled

and modified after Baig & Lawrence, 1987; Greco, 1991;

Wadia, 1931).

J o u rn a l o f R a d i a t i o n R e s e a r c h and A p p l i e d S c i e n c e s 7 ( 2 0 1 4 ) 2 9e3 5 31

(which is divided into lower and upper part based on litho-

logical characteristics) and Quaternary sediments in this area.

The lower Murree Formation in the hanging wall block has

been thrusted on the upper Murree Formation along Muzaf-

farabad Fault in the south of Muzaffarabad. In the Jhelum

valley area the Murree Formation is overlain by the Kamlial

Formation. The geological units in the study area comprise

early Miocene Murree Formation and late Miocene Kamlial

Formation.

3.1. Murree formation

The Murree Formation occupies the major extent within the

study area (Fig. 1b). In Jhelum valley, it is exposed near

Fig. 2 e Indoor gamma dose ra

Niazpura, Langarpura, Paprusa, Khun Bandi, Malasi, Garhi

Dopatta, Kakarwara and Hattian Bala areas. The Murree For-

mation comprises of interbedded sandstones, shales, silt-

stone sand claystones. The sandstone shows cross bedding

and ripple marks. The sandstone is medium grained and

medium to thick bedded. The weathered color of sandstone is

gray to dark gray and reddish brown while fresh color is gray.

The calcite and quartz veins are abundantly present within

the sandstone. The siltstone is thin bedded. The shales of

Murree Formation are reddish brown.

3.2. Kamlial formation

The Kamlial Formation is exposed along the left bank of the

river Jhelum in Kumar Bandiand Garhi Dopatta areas (Fig. 1b).

The formation mainly consists of sandstones, shale’s, clay

stones and minor intra formational conglomerates. The

sandstone is purple gray and blackish gray, medium to coarse

grained, hard and compact. The Kamlial Formation is differ-

entiated from Murree Formation by its spheroidal weathering

and dominance of mineral tourmaline over epidote. The for-

mation overlies the Murree Formation with a transitional

contact while the upper contact is not exposed in the study

area. The age of the Kamlial Formation is Late Miocene.

4. Results and discussion

Results of indoor and outdoor gamma radiation dose rates are

shown in Figs. 2 to 7. Fig. 2 gives indoor gamma dose rates for

Kakerwara region (Zone#1) of Jhelum Velley. Minimum indoor

gamma dose rate value 610 � 4.05 mGy$y�1 (70 nGy$h�1) was

recorded at two places (location site 2 & 4) of Kakerwara lying

at latitudes of 34�11085400 N, 34�2012500 N and longitudes of

73�0089600 E and 73�40089100 E respectively, whilst maximum

value 1372 � 2.7 mGy$y�1 (157 nGy$h�1) was measured at

location site 18, situated at latitude of 34�11088000 N and

longitude of 73�40086100 E. Arithmetic Mean (A.G) and Geo-

metric Mean (G.M) was found as 978 � 3.2 mGy$y�1

(112 nGy$h�1) and 954 � 3.24 mGy$y�1 (109 nGy$h�1) respec-

tively. For outdoor measurements, minimum outdoor gamma

dose rate 495 � 4.49 mGy$y�1 (57 nGy$h�1) was recorded at

location site 6 (as may be seen in Fig. 3), situated at latitude of

34�12018600 N and longitude of 73�41005700 E, whilst maximum

value 1296 � 2.78 mGy$y�1 (148 nGy$h�1) was recorded for

tes in Kakerwara (Zone#1).

Fig. 3 e Outdoor gamma dose rates in Kakerwarha (Zone#1).

J o u r n a l o f R a d i a t i o n R e s e a r c h and A p p l i e d S c i e n c e s 7 ( 2 0 1 4 ) 2 9e3 532

location site 18, situated at latitude of 34�11085700 and longitude

of 73�40086000 N. A.M and G.M gamma dose rate values for

outdoormeasurementswere found as 1013� 3.14 mGy$y�1 and

982 � 3.19 mGy$y�1 respectively.

Fig. 4 gives indoor gamma dose rates for Lawasi region of

Jhelum Velley (Zone#2). Minimum indoor gamma dose rate

value (686 � 3.82 mGy$y�1) was recorded at location site 5& 19

of Lawasi lying at latitudes of 34�14040700, 34�14038900 N and

longitudes of 73�36053000 E, 73�36052100 E, whilst maximum

value (1219 � 2.86 mGy$y�1) was measured at location site 6,

situated at latitude of 34�14041200 N and longitude of 73�36052700

E. A.M and G.M dose rate values for indoor measurements

were found as (913 � 3.31 mGy$y�1) and (903 � 3.33 mGy$y�1).

For outdoor gamma dose measurements, minimum out-

door gamma dose rate (762 � 3.62 mGy$y�1) was measured at

location site 12 & 20 (as may be seen in Fig. 5), situated at

latitudes of 34�14043600 N, 34�14043100 N and longitude of

73�36049200 E, 73�36049900E, whilst maximum value

(991 � 3.18 mGy$y�1) was recorded for location site 8, situated

at latitude of 34�14039400 N and longitude of 73�36054000. A.M and

G.M dose rate values for outdoor measurements were found

as (867 � 3.4 mGy$y�1) and (865 � 3.4 mGy$y�1).

Results for Zone#3 can be seen from Figs. 6 and 7. Fig. 6

gives indoor gamma dose rates for Hattian Dopatta region of

Jhelum Velley. Minimum indoor gamma dose rate value

(686 � 3.82 mGy$y�1) was recorded at location site 28, lying at

latitudes of 34�13083800 N and longitudes of 73�36084100 E, whilst

maximum value (1296 � 2.78 mGy$y�1) was measured at loca-

tion site 34, situated at latitude of 34�13082800 N and longitude

Fig. 4 e Indoor gamma dose

of 73�36088900 E. Arithmetic Mean (A.G) and Geometric Mean

(G.M) was found as (935 � 3.27 mGy$y�1) and

(927 � 3.28 mGy$y�1) respectively.

For outdoor measurements, minimum outdoor gamma

dose rate (686 � 3.82 mGy$y�1) was recorded at two location

sites 17 & 22 (as may be seen in Fig. 7), situated at latitude of

34�13093400 N, 34�13089700 N, and longitude of 73�36082300 E,

73�36081300E, whilst maximum value (991 � 3.18 mGy$y�1) was

recorded for location site 34, situated at latitude of 34�13082800

N and longitude of 73�36088200 N. A.M and G.M gamma dose

rate values for outdoor measurements were found as

(845 � 3.44 mGy$y�1) and (841 � 3.45 mGy$y�1) respectively.

Gamma dose rates were measured at 166 sites for both

indoor and outdoor cases. Overall arithmetic mean (A.M) and

geometric mean (G.M) values of gamma dose rates for indoor

and outdoor measurements were found as 940� 3.26 mGy$y�1,

892 � 3.35 mGy$y�1 and 928 � 3.28 mGy$y�1, 880 � 3.37 mGy$y�1

respectively.

4.1. The annual effective dose equivalent (AEDE)

Measured absorbed gamma dose rates were used to calculate

the annual effective dose equivalent (AEDE) received by peo-

ples of surveyed area. For calculating AEDEwe have used dose

conversion factor of 0.7 Sv/Gy and the occupancy factor for

indoor and outdoor was 0.75 (18/24), and 0.25 (6/24) respec-

tively. Occupancy factor for indoor and outdoor situations

were calculated based upon interviews with peoples of the

study area. Peoples of study area spent almost 6 h in outdoor

rates in Lawasi (Zone#2).

Fig. 5 e Outdoor gamma dose rates in Lawasi (Zone#2).

J o u rn a l o f R a d i a t i o n R e s e a r c h and A p p l i e d S c i e n c e s 7 ( 2 0 1 4 ) 2 9e3 5 33

and 18 h in indoor environment. This occupancy factor (OF)

changes for women of the Hattian Dopatta area who spent

slightlymore time in indoor environment as compared tomen

(O.F ¼ 5/24 for indoor, 19/25 for outdoor environment). The

annual effective dose is determined using the following

equations

AEDEðIndoorÞðmSv=yÞ ¼ Absorbed dose rateðnGy=hÞ � 8760 h

� 0:7 Sv=Gy� 0:75

AEDEðOutdoorÞðmSv=yÞ ¼ Absorbed dose rateðnGy=hÞ� 8760 h� 0:7 Sv=Gy� 0:25

In the UNSCEAR 1993 report the Committee used 0.7 Sv/Gy

for the conversion coefficient from absorbed dose in air to

effective dose received by adults. Estimated values of annual

effective dose equivalent for indoor exposures ranges from

0.32 to 0.72 mSv/y with mean value of 0.49 mSv/y. For outdoor

exposure AEDE ranges from 0.106 to 0.240 mSv/y with mean

value of 0.164mSv/y. Resulting average of the annual effective

dose is 0.654 mSv/y, which is large as compared to the

resulting worldwide average of the annual effective dose

0.48 mSv.

4.2. Excess lifetime cancer risk (ELCR)

Based upon calculated values of AEDE, Excess Lifetime Cancer

Risk (ELCR) is calculated using Eq. (1).

Excess lifetime cancer risk ðELCRÞ¼ AEDE�Average duration of life ðDLÞ � Risk factor ðRFÞ

(1)

where AEDE, DL and RF is the annual effective dose equiva-

lent, duration of life (66 years) (http://en.worldstat.info/Asia/

Fig. 6 e Indoor gamma dose rates

Pakistan) and risk factor (Sv�1), fatal cancer risk per sievert.

For low dose background radiations which are considered to

produce stochastic effects, ICRP 60 uses values of 0.05 for the

public exposure (Taskin, Karavus, Topuzoglu, Hindiroglu, &

Karahan, 2009).

ELCR for indoor exposure ranges from 1.057 � 10�3 to

2.377� 10�3 with an average value of 1.629� 10�3. For outdoor

exposure, ELCR varies from 0.352 � 10�3 to 0.792 � 10�3 with

mean value of 0.543 � 10�3.

Highest A.M and G.M values for indoor 978 � 3.2 mGy$y�1

(112 nGy$h�1) and 954 � 3.24 mGy$y�1, (109 nGy$h�l) and out-

door 1013� 3.14 mGy$y�1, (116 nGy$h�1) and 982� 3.19 mGy$y�1

(112 nGy$h�1) measurements were recorded in Zone#1

(Kakerwara region), which lies in Murree Formation. No spe-

cific relation exists between indoor and outdoor gamma dose

rates. Majority of indoor measurements were carried out in

houses with concrete and wooden flooring. Presence of

wooden walls and floors contribute less towards the external

exposure. This may be the reason of lower values of indoor

A.M and G.M.

Murree Formation is exposed mainly with lithology

comprising of interbedded sandstones, shale’s, siltstone sand

clay stones. The sandstone is medium grained andmedium to

thick bedded. The calcite and quartz veins are abundantly

present within the sandstone. The siltstone is thin bedded.

The shale’s of Murree Formation are reddish brown. Varia-

tions in ambient gamma dose rate for three Zones can be seen

from Figs. 2e7. All three Zones under investigation lies in

Murre Formation, exposed by almost the same lithology.

External exposures from outdoor sources arises mainly from

radionuclide’s present in trace amount in soils, rocks. For

current study mean outdoor gamma dose rates may be due to

Shales, which contains relatively higher levels of radionuclide

concentrations. The outdoor variations of gamma dose rates

in Hattian Duppatta (Zone#3).

Fig. 7 e Outdoor gamma dose rates in Hattian Duppatta (Zone#3).

J o u r n a l o f R a d i a t i o n R e s e a r c h and A p p l i e d S c i e n c e s 7 ( 2 0 1 4 ) 2 9e3 534

from place to place may be attributed due to change in

weathering conditions. As under changing weathering con-

ditions, fluctuations in radon progeny concentration in air

take place due to rainfall, soil moisture and snow cover

(UNSCEAR 2000). High absorbed dose rates in air for Zone#1

may be due to associated with thorium-bearing and uranium-

bearing minerals in the soil.

Linear regression mathematical expression (Y ¼ A þ B*X)

for indoor and outdoor gamma dose rates is given in Eq. (2).

Indoor gamma dose rate ¼ 628þ 0:28119

�Outdoor gamma dose rate (2)

Linear correlation analysis between indoor and outdoor

gamma dose rates has been shown in Fig. 8, with slope of

0.29466. The value of linear correlation coefficient (r) between

indoor and outdoor gamma doses rates was found as 0.29466.

This shows that gamma dose rates have no correlation with

altitude. Probability value ‘p ¼ 0.00685’ shows slight depen-

dence of variations in indoor gamma dose rates with outdoor

gamma dose rates.

Overall mean indoor/outdoor gamma dose rates obtained

for current study is compared with the data obtained for

different studies conducted in different parts of world and

recapitulated in the UNSCEAR (2000) report. Mean indoor and

outdoor gamma dose rates measured for current study were

Fig. 8 e Variation of indoor with outdoor gamma dose

rates.

found as 940 � 3.26 mGy$y�1 (107 nGy$h�1) and

1013 � 3.14 mGy$y�1 (116 nGy$h�1), respectively. Indoor

gamma dose rate measured for the current study is greater

than those reported for various countries including New

Zealand (175 mGy$y�1), United states (333 mGy$y�1), Japan

(464 mGy$y�1), Denmark (473 mGy$y�1), United Kingdom

(526 mGy$y�1), Poland (587 mGy$y�1), Greece (587 mGy$y�1),

Germany (613 mGy$y�1), Finland (639 mGy$y�1), France

(657 mGy$y�1), Norway (692 mGy$y�1), Slovenia (657 mGy$y�1),

world population-weighted average for indoor gamma dose

rates (780 mGy$y�1 or 89 nGy h�1), Hungary (832 mGy$y�1),

China (867 mGy$y�1) Portugal (885 mGy$y�1) Italy (920 mGy$y�1),

Australia (902 mGy$y�1) (UNSCEAR (2000)) and Muzaffarabad,

Pakistan (761 mGy$y�1) (Rafique, 2013). On the other hand

measured average values of gamma dose rate for different

regions of Jhelum valley are smaller than the values reported

for countries like, Iran (1007 mGy$y�1) and Spain (964 mGy$y�1)

(UNSCEAR (2000)).

Outdoor gamma dose rate measured for current study

928 � 3.28 mGy$y�1 (106 nGy$h�1) is higher than the values

previously reported by Rafique, 2013 and Rafique, Basharat,

et al., 2013, 710 � 3.75 mGy$y�1 and 893.5 mGy$y�1

(102 nGy$h�1) for Muzaffarabad and Poonch respectively and

for the Greek population, i.e. 280 mGy$y�1 (32 nGy h�1) (Clouvas

et al., 2004). Current outdoor gamma dose rates are less than

the values, reported for Turkey, 686 to 1189 mGy$y�1

(78.3e135.7 nGy h�1) (Erees et al., 2006) and Japan 121 to

1638 mGy$y�1 (13.8 nGy h�1 to 187 nGy h�1) (Chikasawa et al.,

2001).

5. Conclusion

To measurement indoor and outdoor gamma dose rates have

been carried out in Jhelum valley using Ludlum micro meter

19. Following results are drawn from the current survey;

1. For all three Zones, minimum and maximum indoor

gamma dose values were found as 610 � 4.05 mGy$y�1 and

1372 � 2.7 mGy$y�1, respectively.

2. Minimum and maximum outdoor gamma dose value was

found as 495 � 4.49 mGy$y�1 and 1296 � 2.78 mGy$y�1,

respectively.

3. Overall arithmetic mean (A.M) and geometric mean (G.M)

values of gamma dose rates for indoor and outdoor mea-

surements were found as 940 � 3.26 mGy$y�1,

J o u rn a l o f R a d i a t i o n R e s e a r c h and A p p l i e d S c i e n c e s 7 ( 2 0 1 4 ) 2 9e3 5 35

892 � 3.35 mGy$y�1 and 928 � 3.28 mGy$y�1,

880 � 3.37 mGy$y�1 respectively.

4. Average values of indoor and outdoor gamma doses were

found to be greater than the world population-weighted

average for indoor gamma dose rates (780 � 3.58 mGy$y�1

or 89 nGy h�1),

5. Estimated values of annual effective dose equivalent for

indoor exposures ranges from 0.32 to 0.72 mSv/y withmean

value of 0.49 mSv/y. For outdoor exposure AEDE ranges from

0.106 to 0.240 mSv/y with mean value of 0.164 mSv/y.

6. ELCR for indoor exposure ranges from 1.057 � 10�3 to

2.377 � 10�3 with an average value of 1.629 � 10�3. For

outdoor exposure, ELCR varies from 0.352 � 10�3 to

0.792 � 10�3 with mean value of 0.543 � 10�3.

Acknowledgments

The authors are thankful to the University of Azad Jammu and

Kashmir, Muzaffarabad, Pakistan, for providing the laboratory

and research facilities.

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