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ICRP: Free the Annals!

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Submitted by Bertrand Theriault, Canadian Nuclear Safety Commission
   Commenting on behalf of the organisation
Document Radiological Protection against Radon Exposure

1.      The title is a somewhat misleading since the document is primarily focused on the application of ICRP 2007 recommendations with respect to radon than it is on practical radiological protection against radon (such as that in the section on uranium mining).  It is suggested that the title be changed to reflect this, for example “Application of the ICRP Recommendations for Radon and Radon Progeny”.

2.      Line  67: “…and the level of ambition of the national authorities” sounds deprecating, suggest alternate wording such as “the accepted level of risk of the national authorities” or “risk tolerance of the national authorities”.

3.      Line 179:   This paragraph describes what happens to the unattached fraction, but there is no mention of the decay products that are attached to small dust particles and are deposited in the lungs.

4.      Lines 188 & 189: “There is now compelling evidence that radon and its progeny can cause lung cancer”.  There has been “compelling evidence” from uranium mine studies since the mid-1970’s.  Do you mean at low concentrations of radon in homes? This also applies to line 353.

5.      Line 189 States that there is compelling evidence that radon and its decay products can cause lung cancer.  Is there any direct evidence that radon causes lung cancer?  The cancer risk is from the progeny, not radon itself. This also applies to line 353.

6.      Line 229: It is suggested to replace “ambition” with “goal” or “objective” and elsewhere in the document.

7.      Line 372: There appears to be some text missing. Suggest stating “is a decision that should be taken by the national authorities”.

8.      Lines 706 & 707: The sentence stating  “Depending on the ventilation rate of the building, radon gas can concentrate as compared to outdoor air” is a little confusing.  Suggest changing to: “Depending on the ventilation rate of the building, radon gas can collect and can reach much higher concentrations than that found in outdoor air.”

9.      Line 806: It would be useful to provide the typical range of equilibrium factors outdoors and indoors.

10.  Line 1555:  It is not clear by what is meant by “A positive list of…”.

11.  Line 1558: Suggest not starting with the word “Anyway,”. It should be removed or a term such as “Finally,” or “Nevertheless” should be used.

12.  Figure 7: It should be noted that it might be possible to exceed 10 mSv/a from residential occupancy (7000 hours per year) to 300 Bq/m3 of radon gas, depending on the equilibrium factor, as well as from exposure to 300 Bq/m3 of radon gas both at home and at work. For exposures at the workplace, 300 Bq/m3 would result in much less than 10 mSv/a. It would be beneficial to address this in the text.

13.  Line 1668: Suggest reconsideration of the use of radon maps.  They have proved to be  counter productive as in many cases the radon data for regions were only from a few measurements and home owners were making decisions on whether or not to monitor for radon based upon the map.  There should be a strong statement encouraging radon levels be measured in enclosed buildings, irrespective of radon maps or even results of neighboring buildings since two buildings side-by-side can have very different results.

14.  Line 1780: The suggestion to convert radon progeny concentrations to radon concentrations using the F factor is backwards since the risk is from the radon progeny and the dose is calculated from the progeny as well.  It is known that for residential buildings radon is usually used as the indicator because long-term monitoring is required, but it is a surrogate for the radon progeny risk; most monitors measure radon progeny and convert it to radon concentrations.  This is well explained in the text. Also, using a generic F factor adds extra error to the measurement. Can the ICRP provide equivalent numerical guidelines for radon progeny?

15.  Lines 1783 to 1823: This section appears to be contradictory with respect to radon maps. A stronger statement is recommended saying that while maps are a good indication of radon prone areas, all homes with a potential to have elevated radon levels be monitored at least once during the seasons in which they are the most tightly sealed (i.e. heating season in northern climates, cooling season in warmer climates).

16.  In chapter 4.3 (Radiological protection of workers in the uranium mining industry) suggest mention that because of rapidly changing conditions such as radon sources, changes in ventilation and the need for rapid measurements, it is more practical to monitor radon progeny concentrations than radon.  Also, there should be a mention that personal radon progeny dosimeters are available.