Physical Science Unit

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Residential Radon Exposure in Dwellings of
Kathmandu Valley (Nepal)
Dr. Buddha Ram Shah F. JSPS Senior
Scientist Nepal Academy of Science and Technology
(NAST)
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Brief Introduction of NAST Activities
Radon Monitoring Program
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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
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Introduction
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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...
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Production of Radon and its daughters from
Uranium decay.
Pu-218 (3.05m)
Ra-226 (1600yr)
Pb-206 Stable
U-238
Rn-222 (3.8days)
Po-210 (138.4days)
Pb-214 (26.8m)
Bi-210 (5.01day)
Bi-214 (26.8m)
Pb-210 (21yr)
Po-214 (164µs)
Long Lived Pollutants
Short lived pollutants
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Radon entry inside the dwelling
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Damage of DNA due to Ionizing Alpha particle

• Alpha
• Particle

Free Radical Formation
Double Strand DNA Breaks
Defects in tumor suppressor genes p53
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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.

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Materials and Methods

• Material Kodalpha Radon Dosimeter developed by
  KODAK company, France
• Type Type II, LR115 film plastic track
  detector
• Dimensions 4.0cm7.5cm0.5 cm
• Composition of LR115 film 12µm thin film of red
  coloured Cellulose nitrate coated in 100µm thick
  polyester base.

SSNTD
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Track Analysis Etching
LR115 Film
Under Optical Microscope (300X)
Etching 2.5 M NaOH, 60 0C for one and half hour
alpha tracks
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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.
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Working formula

•  

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Calibration Factor

• As determined by Dosirad Laboratory France, the
  calibration factor of our dosimeter was
• 2.1 tracks/cm2 1 kBqh/m3

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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 (Bq/m3) Radon Concentration in (Bq/m3) Radon Concentration in (Bq/m3) Annual Effective dose in (mSv)
S.N. Name of district  Total number of Dwellings Minimum Maximum Average2s Annual Effective dose in (mSv)
1. Bhaktapur 12 368 41571 9017 1.54
2. Kathmandu 20 82 16129 5611 0.96
3. Lalitpur 9 82 787134 9317 1.59
Arithmetic mean Arithmetic mean Arithmetic mean Arithmetic mean Arithmetic mean 8015 1.36
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  Average radon concentration in
bedroom and kitchen of different dwellings of
Bhaktapur district
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Average radon concentration in bedroom and
kitchen of different dwellings of Kathmandu
district
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Average radon concentration in bedroom and
kitchen of different dwellings of Lalitpur
district
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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.
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Radon Awareness Program
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Program in Pokhara- Amar Singh HSS
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wGojfb .
Thank You!