Residential Radon Exposure in
Dwellings of Kathmandu Valley
(Nepal)
Dr. Buddha Ram Shah F. JSPS
Senior Scientist
Nepal Academy of Science and Technology
(NAST)
Brief Introduction of NAST & Activities
Radon Monitoring Program
Nepal Academy of Science and Technology
(NAST)
Establishment
Established by a Royal
Ordinance as an autonomous
apex body in December 5, 1982
Promulgation of RONAST Act
by the Parliament of Nepal in
1991
NAST Act revisions by the
Parliament of Nepal in 2007
Introduction
RADON ?????
Radon is a colorless, odorless, tasteless,
naturally occurring radioactive gas produced
from the decay of the element radium, which
occurs naturally in rocks and soil worldwide…..
2nd leading cause of Lung Cancer after smoking...
Production of Radon and its daughters from
Uranium decay.
U238
Ra226
(1600
yr)
Rn-222
(3.8day
s)
Pu-218
(3.05m
)
Pb-214
(26.8m
)
Po-210
(138.4
days)
Pb-206
Stable
Bi-210
(5.01d
ay)
Bi-214
(26.8m
)
Po214
(164µ
s)
Short lived pollutants
Pb210
(21yr)
Long Lived
Pollutants
Radon entry inside the dwelling:
Damage of DNA due to Ionizing Alpha
particle:
Alpha
Particle
Defects in tumor
suppressor genes – p53
Objective:
To evaluate the Radon activity concentration in
(Bq/m3) over the exposure time of 100 days.
To determine the annual effective dose from Radon in
(mSv/yr).
To evaluate the concentration of radon progeny in
terms of Potential Alpha Energy Concentration
(PAEC) in (mWL).
To determine the life time fatality risk due to radon.
Materials and Methods:




Material: Kodalpha Radon
Dosimeter developed by
KODAK company, France
Type: Type II, LR115 film
plastic track detector
Dimensions:
4.0cm×7.5cm×0.5 cm
Composition of LR115 film:
12µm thin film of red
coloured Cellulose nitrate
coated in 100µm thick
polyester base.
SSNTD
Track Analysis: Etching
LR115 Film
Ionization
Under Optical
Microscope
(300X)
Etching:
2.5 M NaOH,
60 0C for one
and half hour
Swift
moving αparticle
alpha tracks
Experimental Details:
 Altogether 41 numbers
of dwellings around
Kathmandu Valley,
were selected.
 Two rooms including
kitchen and bedroom
were selected in each
house.
 Houses were concrete
with plastered walls
and proper ventilation
system.
 Dosimeters were
installed at the height
of 2m from the floor
for 100 days.
Radon Dosimeter hanged
on the wall.
Working formula:
Calibration Factor:
As determined by Dosirad
Laboratory France, the
calibration factor of our
dosimeter was
2.1 tracks/cm2 = 1 kBqh/m3
Result and Discussions:
Table shows Average radon concentration, annual exposure, annual
effective dose and life-time fatality risk of Kathmandu Valley.
S.N.
Name of district
Total number of
Dwellings
Radon Concentration in
Annual
(Bq/m3)
Effective dose in
(mSv)
Minimum
Maximum
Average±2σ
1.
Bhaktapur
12
36±8
415±71
90±17
1.54
2.
Kathmandu
20
8±2
161±29
56±11
0.96
3.
Lalitpur
9
8±2
787±134
93±17
1.59
80±15
1.36
Arithmetic mean
350
300
250
200
150
100
50
0
Su
rya
bin
ay
ak
Lu
ka
Ga ntha
tht
l
ha i
g
Du har
wa
k
Du ot 1
wa
ko
Jh t 2
au
kh
el
Sa
lla
gh
Ch ari
un
d
Du evi
dh
pa
ti
Ka
T
ma him
i
lbi
na
ya
k
Bo
de
Average Radon Concentration (CRn)
400
CRn in Bedroom
CRn in Kitchen
Name of place
Average radon concentration
in bedroom and
kitchen of different dwellings of Bhaktapur district:
an
th
Ba a
Ki laju
rti
Ki pur
rti 1
pu
r2
N
Sh
an axal
tin
ag
Te ar
ku
1
Mi Teku
n
Ma bha 2
ha wan
r
Ba ajgu
n
n
Gu eshw j
rju or
So dhar
rak a
Ha hut
ttig te
au
Jo da
rp
Dh ati
a
Ma pasi
Sin itide
v
a
An mang i
am al
na
Ka gar
lan
ki
Bu
da
nil
k
Average Radon Concentration (CRn)
Average radon concentration in bedroom and kitchen of
different dwellings of Kathmandu district:
160
140
CRn in Bedroom
CRn in Kitchen
120
100
80
60
40
20
0
Name of place
Average radon concentration in bedroom and
kitchen of different dwellings of Lalitpur district:
700
CRn in Bedroom
CRn in Kitchen
600
500
400
300
200
100
0
Dh
ap
aH
eig
Go
ht
da
m
Ch
au
r
Kh
um
alt
ar
Ha
ttib
Ma
an
ng
al
Ba
zar
Gw
ark
o
Dh
ob
igh
at
La
ga
nk
he
l
Sa
tdo
ba
to
Average Radon concentration (CRn)
800
Name of Place
Conclusion:
 The measurements indicate higher radon concentration in industrially polluted
and densely urbanized areas like Kamalbinayak, Kirtipur, Maharajgunj,
Sinamangal and Godam Chaur of Kathmandu valley.
 We found the radon concentration is maximum in kitchen than in bedroom in
most of the dwellings due to extra contribution of radon from water and cooking
gas, kerosene, etc.
 The low radon level in most of the concrete houses with plastered walls is due to
the proper ventilation system. Also the cement impedes the flow of radon as it has
low permeability.
 Although, the overall concentration of radon and annual effective dose of radon
and its progeny in Kathmandu valley are well within the action level (200-600
Bq/m3 and 3-10 mSvy-1) of International Commission of Radiological Protection
(ICRP-103, 2007) , one of the places that is Godam Chaur area of Lalitpur district
is under the significant radiological threat to the population.
Radon Awareness
Program
Program in Pokhara- Amar Singh HSS
wGojfb .
Thank You!