ICRP Draft Report on Radiological Protection against Radon Exposure
Comments by Ingvild Finne and Anne Liv Rudjord
(representing Norwegian Radiation Protection Authority)
The new ICRP report on radiological protection against radon exposure is welcomed by NRPA, and the draft indicates that it will be a step forward and a substantial improvement of the guidance to authorities regarding this issue.
Section 3.1.1 Types of exposure situations
NRPA considers that radon exposure can be classified as planned exposure situations in relation to construction of new buildings and the active use of land planning to reduce radon exposure.
Section 3.2 Justification of protection strategies
NRPA support the idea that a radon protection strategy is generally justified.
We also agree that it would be difficult to deal separately with radon for smokers, former smokers and non-smokers, especially for the public health aspects of the strategy. However, the elevated risks from radon for smokers and former smokers should be communicated to the public. In addition, smoking habits may need to be taken into account in the follow-up of individuals who have been exposed to very high radon concentrations over time .
Section 3.3.2 Upper value for reference level in concentration
In paragraph 85 the Commission recommends to use the same reference level for dwellings, mixed-used buildings and as a first approach also for most workplaces. NRPA supports this.
This approach is easier to communicate to the public and others, and in most cases it is reasonable. It is important to keep the system simple and intuitive in order to limit the amount of time and resources spent on each individual building. In most cases, the cost of radon mitigation is moderate. At the same time a large number of buildings need to be mitigated, and for cost effectiveness we believe a high degree of standardization is needed in every step of the management of radon. Resources should as far as possible, be used to reduce radon exposure and not on managing complicated protection systems. However, some workplaces will require a more complicated regime, ref. sub-section 3.3.6 below, but this will apply to relatively few workplaces.
Section 3.3.6 Specific graded approach for workplaces
NRPA recognizes the need for a graded approach to manage radon exposures at workplaces.
The first step in this philosophy is to apply the national reference level (given as radon concentration in a building or location) as defined for dwellings, mix-use buildings, schools and also the workplace. NRPA supports this integrated approach, as it is simple and in most cases realistic and reasonable. The majority of workplaces can be managed this way.
However, there are clearly cases where it would not be practical or appropriate to manage radon using a reference level on concentration. Examples could be some underground work-places where radon concentrations varies with time partly due to the nature of the work such as mining and tunnel construction. However, it seems too complicated to introduce another two steps in the protection against radon at workplaces where the workers are not defined as occupational exposed, cf figure 7. NRPA suggest that when the optimisation for the workplace does not lead to a radon concentration below the national RL on concentration, the workers should be defined as occupationally exposed. In such cases, all the tools available for controlling doses for the occupationally exposed (cf section 4.2) could be used.
NRPA therefore does not support a separate dose reference level of 10 mSv.
4.1.1 National radon action plan
The guidance in the draft report for development of strategies and action plans contains many useful elements which is supported by the experiences from management of radon in Norway.
For instance we welcome the recommendation that the protection strategy should primarily aim to control radon through management of buildings.
Especially important is the focus of long term perspective on reduction of radon exposure, and the preventive actions in new buildings to reduce the future exposures. Without these elements, radon reduction will be more costly and less effective.
However, the national radon strategy/action plan should include further guidance on national management of areas or homes with exceptionally high radon concentrations or individuals who have received very high doses.
In many countries, new homes or workplaces with radon concentrations of several thousands of Bq/m3 are discovered quite frequently. In some cases whole communities are affected. The management of such situations can be quite complex and coordination of contributions from several national authorities dealing with the different aspects of the “crisis” could be required (information, health care follow-up on individual basis, economics, geology, mitigation, …).
If areas of exceptionally high radon concentrations is not dealt with in an appropriate way and people continue to live and work in exceptionally high radon concentrations, this could undermine national work on radon.
Shortly after the discovery of an area with exceptional high radon concentrations the inhabitants in the area and the persons involved directly often feel anxious and should be given sufficient and appropriate information. However, experience shows that quite often the problem is not taken seriously enough or is even denied by the communities in question, and people are continuing to live in homes with annual mean radon concentrations of several thousands of Bq/m3. Information is of course crucial, and should be agreed on and coordinated between the national, regional and local authorities.
The discovery of homes with exceptional high radon concentrations raise the question of an upper radon concentration above which the home is not considered to be habitable. Guidance from the ICRP on such an upper limit for which either authorities or others need to take action also in private homes would be appreciated. An upper value would raise new questions, like who is going to pay for a new home or the mitigation. This question could be left for the national strategy/action plan.
Section 4.1.3 Mitigation
The last sentence in paragraph 147 should be removed:
(147) Once radon-prone areas are identified, the national radon action plan should develop special mitigation programmes for these areas, providing that these areas include a large fraction of buildings with estimated high radon concentrations. New and existing buildings should be covered by these programmes. Some preventive and protective actions may concern the whole territory of the country. However, the radon map should never result in areas where buildings are forbidden.
NRPA considers that the option to ban new construction may be a good option in extreme cases for very small, limited areas. Areas with extreme radon outflow or very high outdoor concentrations do exist, and even a well-constructed building could result in long term serious radon problems. Such a ban should of course be used cautiously, but it should be the decision of the national authorities whether it should used, and whether or not it should be based on a map of radon-prone areas.
We suggest that the consistency and correlation between the executive summary, the main points and the full report should be reviewed carefully.
We noted the two following points as well:
1. Reference levels for radon are mostly given as concentrations, and this should be reflected:
494 Reference level
495 In existing exposure situations, this represents the level of radon concentration, dose or risk,
496 above which it is judged to be inappropriate to plan to allow exposures to
496 occur, and below which optimisation of protection should be implemented.
2. The radon concentration will be diluted when entering a building from the soil. It does not concentrate. However, radon is less diluted in buildings than outdoor.
707the ventilation rate of the building, radon gas can concentrate as compared to
708 outdoor air.