Elaine R. R. Rochedo

Transcription

1 Elaine R. R. Rochedo

2 Summary ICRP recommendations on exposure to radon New BSS requirements Comments Public Exposure General Some suggestions for a National Radon Program

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4 Radon -ICRP Reccommendations 1959 ICRP 2 Rn as beta/gamma emitter Critical tissue approach Maximum dose equivalent to the epithelium of lung: 0.15 Sv lung model 30 pci/l (1100 Bq/m 3 ) Rn-222 in equilibrium with daughters 1977 ICRP 24 miners - endorsed ICRP 2 Equilibrium factor is first cited

5 Radon-ICRP Recommendations ICRP 26 Effective dose Dose limit for workers: 50 msv/y Dose limit for the public: 5 msv/y Changed w R for alfa particle 1981 ICRP 32 Miners: 50 msv/y 1500 Bq/m 3 (F=1)

6 Radon-ICRP Reccommendations 1984 ICRP 39 Exposure to natural sources Public Existing exposure situations: action level: effective dose of 20 msv/y New exposure situations: upper bound: 10 msv/y 1986 ICRP 47 Workers in mines Endorses ICRP 32

7 Radon-ICRP Reccommendations 1990 ICRP 60 Effective dose limits (Practices): Workers: 20 msv/y Public: 1 msv/y Intervention 1993 ICRP 65 - Radon in homes and working places Change from dosimetric to epidemiological approach Miners = occupationally exposed workers 20 msv/y Other workers = public action level: 3 10 msv/y Public: Bq/m 3 (7000 h; F = 0.4) Working places: Bq/m 3 (2000 h; F = 0.4)

8 Radon-ICRP Reccommendations 2007 ICRP 103 Planned, emergency and existing exposure situations Introduces optimization for existing exposures situations Upper value of 10 msv/y for the individual reference level Endorses 600 Bq/m 3 (public) and 1500 Bq/m 3 (working places) Working places > 1000 Bq/m 3 comply with 20 msv/y 2009 ICRP statement New risk coefficient for radon Keeps reference level of 10 msv/y Public: 300 Bq/m 3 Working places: 1000 Bq/m 3

9 Summary on Radon concentration upper levels 4000 Radon concentration (Bq/m3) year MINERS WORKERS PUBLIC (Vaillant& Bataille, 2012)

10 Radiation Protection and Safety of Radiation Sources: International Basic Safety Standards - Interim Edition General Safety Requirements Part 3

11 NewBSS 5. EXISTING EXPOSURE SITUATIONS SCOPE 5.1. The requirements for existing exposure situations in Section 5 apply to: (c) Exposure due to natural sources, including: (i) 222 Rn, 220 Rn and their progeny, in workplaces other than those for which exposure due to other radionuclides in the uranium or thorium decay chains is controlled as a planned exposure situation, in dwellings and in other buildings with high occupancy factors for members of the public;

12 NewBSS 5. EXISTING EXPOSURE SITUATIONS GENERIC REQUIREMENTS Requirement 47: Responsibilities of the government specific to existing exposure situations The government shall ensure that existing exposure situations that have been identified are evaluated to determine which occupational exposures and public exposures are of concern from the point of view of radiation protection.

13 NewBSS 5. EXISTING EXPOSURE SITUATIONS 5.5. The regulatory body or other relevant authority shall implement the protection strategy, including: (a) evaluation remedial actions and protective actions.. and for evaluation of the efficiency of the actions.

14 NewBSS 5. EXISTING EXPOSURE SITUATIONS PUBLIC EXPOSURE Requirement 50: Public exposure due to radon indoors The government shall provide information on levels of radon indoors and the associated health risks and, if appropriate, shall establish and implement an action plan for controlling public exposure due to radon indoors.

15 NewBSS PUBLIC EXPOSURE As part of its responsibilities 5.3, the government shall ensure that: (a) Information is gathered on activity concentrations of radon in dwellings and other buildings with high occupancy factors for members of the public through appropriate means such as representative radon surveys;

16 NewBSS PUBLIC EXPOSURE As part of its responsibilities 5.3, the government shall ensure that: (b) Relevant information on exposure due to radon and the associated health risks, including the increased risks relating to smoking, is provided to members of the public and other interested parties.

17 NewBSS PUBLIC EXPOSURE Where activity concentrations of radon that are of concern for public health are identified on the basis of the information gathered as required in para. 5.19(a), the government shall ensure that an action plan is established comprising coordinated actions to reduce radon levels for existing buildings and for future buildings, which includes:

18 NEW BSS PUBLIC EXPOSURE (a) Establishing an appropriate reference level for 222 Rn for dwellings and other buildings with high occupancy factors for members of the public with account taken of the prevailing social and economic circumstances that in general will not exceed an annual average activity concentration due to 222 Rn of 300 Bq/m 3 ; (b) Reducing activity concentrations of 222 Rn and consequent exposures to a level at which protection is optimized;

19 NEW BSS Footnote: On the assumption of an equilibrium factor for 222 Rn of 0.4 and an annual occupancy rate of 7000 hours, the value of activity concentration of 300 Bq/m 3 corresponds to an annual effective dose of the order of 10 msv.

20 NewBSS PUBLIC EXPOSURE (d) Including appropriate prevention and mitigation measures for 222 Rn exposure in building codes to prevent the ingress of radon and to facilitate possible remedial actions wherever necessary.

21 NewBSS OCCUPATIONAL EXPOSURE Exposure due to radon in workplaces The reference level for 222 Rn shall be set at a value that does not exceed an annual average activity concentration of 222 Rn of 1000 Bq/m 3, with account taken of the prevailing social and economic circumstances.

22 NewBSS OCCUPATIONAL EXPOSURE On the assumption of an equilibrium factor for 222 Rn of 0.4 and an annual occupancy rate of 2000 hours, the value of activity concentration due to 222 Rn of 1000 Bq/m 3 corresponds to an annual effective dose of the order of 10 msv.

23 NewBSS OCCUPATIONAL EXPOSURE Employers shall ensure that activity concentrations of 222 Rn in workplaces are as low as reasonably achievable below the reference level established in accordance with para. 5.27, and shall ensure that protection is optimized.

24 NewBSS OCCUPATIONAL EXPOSURE If, despite all reasonable efforts by the employer to reduce radon levels, the activity concentration of 222 Rn in the workplace remains above the reference level established in accordance with para. 5.27, the relevant requirements for occupational exposure in planned exposure situations as stated in Section 3 shall apply.

25 PUBLIC EXPOSURE

26 Comment1 PublicExposure Radon is not believed to be a national health problem for most tropical areas of the world. Of course, there may be cases where levels are higher than the 300 Bq/m 3 reccomended levels but these are usually very localized and individualized situations. It would be great to be able to prove that.

27 Indoors radonin Brazil Town XM SD XG range N reference Poços de Caldas, MG urban Veiga et al, 2003 rural Rio de Janeiro, RJ 40 < Magalhães et al, 2003 Rio de Janeiro, RJ Joinvile, SC São Paulo, SP Poços de Caldas, MG Binns et al, Buena, RJ Magalhães et al, 2005 Campinas, SP summer Hadler et al., 2008 winter Lagoa Real, BA Binns et al., 1998 Ingles de Souza, PA Melo, 1999 Monte Alegre, PA <

28 Comment2 PublicExposure Some reccomendations for a national radon survey Start with high background U areas; Start with semi-tropical/temperate climate areas; Look for special NORM uses related situations; For most of the country, consider the survey as a relevant scientific information and not as a public health survey ;

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30 Comment3 Establish standard protocols for dealing with colected measurements data.

31 Samplingmethodology Variabilyon daily radon concentration with the season (from Magalhães et al, 2003) 25,00 20,00 EEC ²²²Rn outdoor 15,00 10,00 5,00 summer autumn w inter spring Hour Levels are to be compared with average annual concentration

32 Type of distribution

33 EUROPEAN MOSAIC (2005) Different: Sampling grids, Color convention, Measurement methodology, Season and measurement period

34 Harmonization procedures (2010) Decided at Prague conference, 2006: 10 x 10 km grid, annual mean ground floor rooms (Gruber et al, 2010)

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37 Samplingmethodology

38 USA Radon map Zone 1 (red) counties with a predicted average indoor radon screening level greater than 148 Bq/m3. Zone 2 (orange) counties with a predicted average indoor radon screening level greater than 74 but lower than 148 Bq/m3. Zone 3 (yellow) counties with a predicted average indoor radon screening level lower than 74 Bq/m3.

39 Final comment Consultation with other organizations (IBGE, EMBRAPA).

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