Radiological Protection against Radon Exposure

Draft document: Radiological Protection against Radon Exposure
Submitted by Neil McColl, Health Protection Agency, UK
Commenting on behalf of the organisation

These more detailed comments supplement the wider points submitted previously



Line 127-128:  Delete ‘as well as the dosimetric reference and the rationale behind’.

Line 140: S. Solomon

Line 145: Delete ‘a’


Executive Summary


Line 176: There is no further mention of thoron in the Executive Summary – this needs to be explained.

Line 185: Change to ‘… may lead to lung cancer’.

Line 194: WLM mentioned without explanation.

Line 266: It is essential that it is recognised that 10 mSv is equivalent to less than 200 Bq/m3 using the dosimetric approach to be adopted by ICRP. There are also references to 10 mSv on lines 291, 294 and 297.

Line 304: “… should be managed as a planned …’


Main Points

Remove reference to 10 mSv in bullets 8 and 10.


Line 490 : At present, the definition of a radon-prone area is relative within the country. That might suggest that every country will have radon prone areas. In reality there may be some countries (admittedly probably only small ones) in which there are no areas in which there is a significant probability of having indoor radon above the adopted reference level. Has ICRP considered a definition of radon prone area in more absolute terms along the lines of “…indicating that buildings in the area have a significant probability of exceeding a radon reference level”.

Line 495 “.....this represents the level of dose or risk” or concentration? At present the definition does not refer to indoor radon levels.

Section 1 : Introduction

Line 582 No title given for Figure 1.

Line 602: Here it is stated that the purpose of the report is to consider protection from radon-222 and radon-220. It is recognised that typical radon-220 values do not present a radiological protection issue. However, exceptional levels are observed but the document does not address radon-220 systematically throughout. The document would benefit from a check that radon-220 issues are considered where appropriate.

Section 2 : Characteristics of radon exposure

Line 654/655: 1950s and 1970s

Line 665: 1990s

Line 683 Need a reference for the radon in soil gas figures

Line 684 Reference for the radon in soil gas figures?

Line 704 Add: ‘Radon-220 concentrations in underground workplaces, however, can be somewhat higher and lead to significant worker exposures.’

Line 707 ......radon gas can be more concentrated compared to outdoor air.

Line 709 Please consider: Depending on meteorological parameters (such as wind, atmospheric pressure, etc) and particularly temperature difference between........

Line 711 Is the pressure differential between the soil and the inside of the building? (not the foundations?)

Line 713 Suggest ‘the sub-slab crawl space if this exists’.

Line 713 Suggest “this pressure driven flow”

Line 714 : many readers may not understand what is meant by “sub-slab crawl space” in some areas it may not be large enough to be a “crawl space”. Add brief explanation?

Line 716 Replace ‘basement slab’ with ‘solid foundations’.

Line 741 It may not be clear to some readers what ‘life style’ or ‘working habits’ refers to. We presume in this instance it refers to the amount of ventilation provided by opening windows? If so, would it be better to describe it in such a way to avoid confusion?

Line 756 Need a reference for the radon in water figures

Line 763 : Not sure which UK reference contains the 70,000 Bq m-3 level. A workplace with this level was measured and there is probably very old publication but this has not proved easy to track down.  It is suggested that a more up to date reference to a similarly high level is used instead.  A level of 65,000 Bq m-3 was reported for a room in a house in the Republic of Ireland (ref: Ref: High radon concentrations in a house near Castleisland, County Kerry (Ireland) – identification, remediation and post-remediation.  C Organo & D Fenton, JRP No 24 Vol 2 107-120, 2004.)

Line 786 The phrase ‘may lead to health effects’ is very weak, considering the conclusions given elsewhere in the report, e.g. Lines 833-867.

Line 810: Please change this incorrect statement to: ‘… as well as factors such as the depth of target cells within the airway linings.’

Line 821: Please delete paragraph 32. The equivalence of “epidemiological” and dosimetric calculation of effective dose per unit radon exposure are complex and this summary is incorrect and unhelpful. For example, a factor of two difference is not a significant discrepancy but good agreement given the uncertainties in both approaches. It can be regarded as coincidental that the same value of around 11-12 mSv/WLM is obtained for miners in both cases.

Line 852 Should the sentence be: ‘The cumulative absolute risk..........’

Line 864 Is this coefficient is valid for members of the public or general population, not workers?

Line 904 : “persistence”. Not quite the right word since there will always be some radon whatever the individual does. Suggest instead “the level of risk”.

Line 904 : “potential for reduction” is only partly dependent on the individual – the initial level of radon is a major factor.

Line 906 : This line generalised too much by saying that “ responsibility for remediation falls on individuals”. It does in the case of the single homeowner but not so in most workplaces and many rented buildings. Add “often”.

Line 910 : Radon mitigation is not really an “adaption of the way of life” but an adaption of the existing living environment. The behaviour of the occupants is essentially unchanged by radon remediation. May be referring to changes in living style eg different ventilation of the property.

Line 913 : it is not clear what is meant by “radiological protection considerations” here. Suggest replace with “radiation exposures ”The factors noted are clearly important in managing radon and radon management, and consideration of most of these factors, has been part of UK and other nations’ radiological protection (RP) for over two decades. Indeed, in wider RP, factors such as economic and social, have been part of RP for many years.

Line 922 Replace ‘Similar to a contaminated area’ with ‘Similarly to an inhabitant of a contaminated area’

Line 929 Replace ‘the question is who can help him to deal with the radon issue’ with ‘this person will require help, locally or nationally, to assist with radon control measures’

Line 958 : Add: “as building codes become more established and widely implemented.”

Line 959 Suggest simplify by “integrating with” other plans…

Line 965 : The claim of reduction by more than a factor of ten ought to be qualified along lines of “if an appropriate method is properly installed” and include a reference.

Line 966 : It might be useful if this paragraph were also to note (as WHO 2009 Handbook notes on p12) that the “dose-response relationship appears to be linear with no evidence of a threshold”.

Line 976 : Is there any evidence that radon, other indoor air quality and anti-smoking promote inconsistent actions? It is clear that in the case of radon and smoking, the best course is to take action against both but action on either would do good not harm. I think this refers to inconsistency of policy eg where a policy that improves one has a detrimental effect on the other

Line 981 : A radon strategy should be a permanent (not just “several decades”) feature. The source of radon is ultimately U-238 which for all purposes can be deemed to be a permanent source. New homes, etc are built in radon prone areas, existing buildings are modified leading to changes in radon levels, active radon measures suffer mechanical failure. The radon problem is not solved – it is managed.

Line 988 Replace ‘building’ with ‘premises’ to cover caves, etc

Line 989 Delete ‘Since radon exposure is mainly a domestic issue’. This contradicts the diversity of exposure situations expanded upon in the preceding and following sections.

Line 991 : This ignores the role of landlords. In some countries this is especially important where significant proportions of homes are rented. Perhaps add “…and for landlords to address radon risks in their properties.”

Line 1005 : suggest “staff” not “teachers” – schools have other staff such as administrators, caretakers, cleaners, cooks, etc.

Line 1011 Suggest ‘aim to maximise effectiveness’

Section 3 : Recommendations of the Commission

Line 1094 : should this section recognise that radon is only partially controllable. Outdoor radon levels are not controllable and provide lower ambient indoor level.

Line 1099 Add ‘or transiently during particular meteorological conditions, such as a temperature inversion’.

Line 1100: Delete ‘reasonably’.

Line 1187 while these exposures are not considered “occupational”, they still fall under the category of “public” and warrant protection and places obligations on those who manage the premises and the safety of those who use the premises.

Line 1243 : Suggest AGIR 2009 or WHO handbook 2009 as a suitable reference for the statement that “it seems to be the primary cause of lung cancer in people who have never smoked”.

Lines 1270-72: It will not be possible to maintain 10 mSv as as level above which remedial action will almost always be justified and also keep to a RL of 300 Bq/m3. Similarly, 3-10 mSv on line 1276 will correspond to around 50-170 Bq/m3 using the dosimetric approach. Reference should be made to the 1-20 mSv range as in para 79.

Line 1306 The second band (1-20 mSv) applies when individuals derive direct benefits. Information provision to support individuals protecting themselves is suggested in ICRP as desirable “where possible”. This document should reflect that fact that in many radon situations the individual may not be the controlling body – eg the landlord, manager or employer may be in control of protection decisions and actions.

Line 1310 : better to describe “modern” life as not being possible by relating it to societies that are based within a permanent built environment. There are populations who live largely outdoors but that style of life would not be associated with elevated radon levels.

Line 1312 : It is not clear why the draft document proposes two alternatives of “stay in the home” or “live somewhere else”. The whole basis of radon management is that indoor radon levels can be reduced so the choice proposed is not a relevant one.

Lines 1314-1322: Suggest deletion of para 80 and 81.

Lines 1351/2: Suggest delete ‘… and close to the level of 10 mSv per year’.

Line 1361 : The intended meaning of the phrase “common workshops” is unclear. Is “common” meant to suggest “typical” or “shared” – it can have either meaning in English. Is “workshop” meant as industrial type workshops (eg with manufacturing machinery, etc?)

Line 1388 (Figure 5).  The diagram for Prevention labels the remain dose as being “planned added dose”. It is added dose since the building is new. However, it is not clear that it should be called “planned”.  Experience in UK suggests the performance of prevention measures is generally to provide a proportional reduction on what exposure might have been in the absence of the measures. Neither the absolute level of exposure without or with such measures could reasonably be called “planned”. Secondly, there is potential for such exposures to be confused with “planned exposures” when ICRP considers them to be “existing exposures”. In this case, “residual dose” would be more useful.

Line 1399 Suggest that ‘sporadically’ might be interpreted as being un-managed. This document should advise a measurement regime that is “managed but not frequent”

Line 1416 : The meaning of this sentence is not clear.

Line 1443 As the indoor radon concentration to be expressed in terms of the annual mean (line 272), this should be clear and consistent.

Line 1446 : It should be noted that, because of the generally log-normal distribution of radon exposures, in many countries it may be that the great majority of the population risk (collective exposure) is delivered at levels of individual radon exposure that are lower than the plausible range of reference levels. In UK (AGIR 2009, Table 4.4) it is noted that nearly 90% of the attributable lung cancer deaths from radon occur at levels in the range 0-99 Bq/m3. The effect of lower reference level should be qualified along lines “as long as the associated activities (measurement and remediation) are fully implemented”.

Line 1446 Bringing the reference level down does not necessarily mean that more risk is mitigated, it is dependent on the potential achievement of the reduction method and whether or not the person responsible for the building has attempted to reduce radon levels.

Line 1479 Suggest that at this stage in a radon strategy the focus should be on premises where there is prolonged public occupancy rather than many people with short exposure times. Accepted that collective and repeat exposures may be relevant here.

Line 1532:  Delete or revise para 107 which refers to 10 mSv.

Line 1543: Would this be better to reference a dose reference level in the range 1-20 mSv?

Line 1540 Suggest that more “site-specific” might be better than “realistic”

Line 1546 not clear what is meant by “collective protection”. The aim is still to manage individual exposures but the individual is likely to be a hypothetical, model or “typical” rather than specific people.

Line 1555 Where countries decide to specify such workplaces, should they be advised to have underlying criteria, even if qualitative ones, to support such specifications and to help identify other sectors or types of premises that might shared those characteristics?  It may also be that there are some occupations (for example radon remediators) whose working conditions might justify their exposures being considered to be occupational [see also line 1581].

Figure 7: As line 1543?

Section 4 : Implementation of protection strategies

Line 1661-2 The point appears to be that many of those who may have to take action don’t have specialised knowledge of radon, radiation protection, etc. Therefore, the document should advise along these lines rather than focusing on the “individual” which could be misinterpreted as each individual user of the building.

Line 1665 : reference to “self-measurement” would be better expressed as “access to appropriate radon measurement services”

Line 1701 : suggest that the measurement should be in the building “once finished and occupied” simply constructed may lead to measurements made in unheated, unrealistically ventilated buildings in which radon levels may be significantly different from levels in the building in its occupied state.

Line 1707 : Which “energy saving measures” – give examples. Is the correlation between “energy saving” in buildings and radon levels well established? Is there suitable reference that draws together relevant experience sufficient to provide evidence for this statement?

Line 1716 : it is not obvious where the claim of “prime importance” comes from.  The WHO Handbook (2009, Exec Summary para 8) refers to the twins aims of reducing overall population risks and risks to those living with high radon. There is no suggestion of one aim being more important than the other. If WHO does not express such an importance form a public health point of view, why should ICRP?  Suggest changing sentence to: “…regulations and codes is important from a public health point of view.”

Line 1717 : the issue of cost-effectiveness of preventive measures in all new buildings is generally accepted for radon prone areas but there remain significant uncertainties when extrapolated to all areas, including those with low radon potential. It is suggested that the draft text is amended to read “…authorities should consider the implementation of building regulations or building codes that require radon prevention measures in radon prone areas and potentially all areas, subject to consideration of costs and benefits”.

Line 1729 Replace ‘householders’ with ‘building owners or managers’.

Line 1767 Replace ‘updated’ with ‘reviewed’.

Line 1769-70 Information on radon-220 sensitivity should be provided by the supplier or manufacturer. The implication here is that the customer should perform these tests themselves.

Line 1774 Suggest that this should note that where significant seasonal variation of radon levels occurs, the annual average should take account of this either through appropriate correction factors, limited measurement periods or other appropriate means.


Line 1777 Does the requirement ‘same conditions than as for the initial measurement’ include the exposure duration? This should be much less than a year to test the effectiveness of mitigation promptly.

Line 1798-9 The purpose of the extra measurements is not clear

Line 1802 Replace ‘dwellings’ with ‘buildings’ or ‘premises’.

Line 1808 : This paragraph should note that surface and near-surface geological information, especially coupled with radon measurements, can be (and is) used to identify radon prone areas.

Line 1819 : suggest that in radon prone areas, the national radon action plan should “support the development of measurement and mitigation programmes and services…” Simply referring to “special mitigation programmes” suggests a single jump to large scale mitigation.

Line 1820 : not sure what is meant by “include a large fraction of buildings with estimate high radon levels”. Is this suggesting that the fraction of buildings in the area has to be high (eg at least ¼ or 1/3?) Is it referring to the fraction of buildings in the country with high levels? Might be better to say “…these areas, where a significant proportion of buildings in these areas are estimated to have high radon concentrations”.

Line 1823 : “…buildings are forbidden.” Sounds a bit strong. Is the aim here to reflect experience that even in areas with lots of buildings with high radon levels, there are always many (generally still a majority?) that have low levels and that those that are high can be remedied? Rather than an absolute rule irrespective of the evidence? Perhaps the following words would be better… “Experience shows that even in the most radon prone areas, the majority of buildings either have, can be built with or can be remediated to fairly low indoor radon levels. It is therefore not expected that a radon map would preclude building in an area.”

Line 1829 Replace ‘mitigation’ with ‘radon prevention and mitigation’.

Line 1838 : outdoor air is not “pure” with respect to radon. Better to say “outdoor air at low radon concentration”

Line 1839 Replace ‘dwellings’ with ‘buildings’.

Line 1840 Encouragement of ventilating buildings by using windows should be approached with caution: the ventilation depends on inconsistent human operation – generally this cannot be depended upon as a mitigation measure.

Line 1847 Replace ‘houses’ with ‘buildings’.

Line 1862 : should be “identify and mitigate” – identification through measurement is a key stage in the process.

Line 1863 Suggest re-wording this to focus on targeting communications to those who have to take action.

Line 1880 : Would the reference to “non-smokers” be better as a reference to “non-smokers, especially ex-smokers”, given their greater baseline risk?

Line 1888 : suggest “reviewed to identify areas for improvement, and repeated while significant number of homes with high radon remain either unidentified or not remediated”.

Line 1896 The list of properties with extended public occupancy includes only those where a single person might spend a long period and not those with multiple short occupancies - libraries, shops, etc. This is a more appropriate description of a high risk building than that described in lines 1479-81.

Line 1906-7 In many cases it would be impractical to provide information to members of the public passing through a building undergoing mitigation. If the measures to keep below the reference level are effective, would it be a disproportionate response to “…provide relevant information to members of the public using the building…”? This seems a bit onerous for a risk that is being managed.

Line 1911 Most buildings with public access will be privately owned, e.g. shops so not under direct control of “national authority”.

Line 1924 This is ambiguous - does it refer to a limited period per day, or a short exposure period for each individual person? Suggest should read “where typical member of the public might be present for only a short duration”.

Line 1931: Remove reference to 10 mSv.

Line 1945-8 The control of radon in workplaces is routinely both the management of the building or location, and the control of individual exposures.