AW: [ RadSafe ] Guidance on Outdoor Gamma Dose Rates - Second Request

[Franz Schönhofer]

Leo,

You raise an interesting question, which is not easy to answer. Frankly I do
not know of any such legislation directed to natural gamma radiation in any
country, but I can give you some arguments, why this is probably not of
concern in housing:

In most countries doses from the "undisturbed soil (ground)" are not to be
considered. As soon as for instance someone opens a mining operation the
doses to workers and the population have to be considered. Because of this
legislation it seems to me, that - from the legal point - there could not be
in the countries whose legislation I know any restrictions for extrnal gamma
radiation. 

Part 2 of my comment: Houses usually have foundations and at least newer
ones concrete slabs as a cellar floor. This will provide shielding, so the
really "outdoor" dose rate is not representative for the dose to the
inhabitants of the house. 

Part 3: When looking at potential and actual doses from Rn-222 which occurr
in different parts of the world, the doses you cite from gamma radiation are
not frightening for me, especially when taking into account the above said.
The situation regarding Rn-222 is therefore of much more concern. Some
countries have legislation on indoor radon (Scandinavian ones), almost all
have recommendations. The EU has a recommendation to the member states, but
recommendations are not legally binding and would have to be implemented
into national law.

Part 4: The RP 112 of the EU is very helpful, but again I have to mention
that it is only a recommendation. There also exist national standards on the
radioactivity of building material. In all of them the gamma-dose rate is
either explicitely or implicitely included. In the first case the K-40
concentration has be to considered. 

Part 5: In the Czech Republic there is legislation in force, which
prescribes that in known risk areas an official certified expert has to test
for radon in soil at the planned site for a new house. They evaluate the
radon risk and give recommendations on which measures to take during
construction to reduce the possible radon concentration. An evaluation of
the radon risk is also done in Finland. These are the two countries I
definitely know about, but there might be others as well. 


I hope I gave you a little information and especially food for thought. Feel
free to contact me, if you think I could be of more help.

Best regards,

Franz

Franz Schoenhofer, PhD
MinRat i.R.
Habicherg. 31/7
A-1160 Wien/Vienna
AUSTRIA


-----Ursprüngliche Nachricht-----
Von: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] Im Auftrag
von Leo M. Lowe
Gesendet: Mittwoch, 29. August 2007 18:13
An: radsafe at radlab.nl
Betreff: [ RadSafe ] Guidance on Outdoor Gamma Dose Rates - Second Request

Dear Radsafers,

I previously sent the query below to Radsafe but I have received no 
responses (except for one on the potential hormetic effects of 
elevated background radiation levels).  To repeat, are there any 
reference levels on natural  background gamma radiation relative to 
new residential construction?

Feel free to respond to me directly.
____________________________________________________
Do you know of any criteria/guidelines for outdoor gamma 
dose/exposure rates for natural background radiation; that is, given 
that many people live in areas resulting in annual doses greater than 
1, 2, 5 mSv/y or more, is there any guidance on a background dose 
rate above which people would be advised not to live?  This could be 
an issue, for example, if someone wanted to build a house in an area 
with some natural thorium or uranium mineralization.

I am aware of recommended limits for NORM in building materials (such 
as the European Commission in Radiation Protection 112),  reference 
limits for initiating action for existing situations (ICRP 2007 says 
that remedial action is not likely justified below 10 mSv/y) and of 
limits for indoor radon, but is there any specific guidance on the 
issue of outdoor natural gamma radiation relative to new construction?
____________________________________________________________________________
___________

Leo M. Lowe, Ph.D., P.Phys.

SENES Consultants Limited
llowe at senes.ca
www.senes.ca
Tel:  905-764-9380
Fax: 905-764-9386