1. Field Methods Rado Copyright © 2012 by DBS

3. Contents What is radon? Health effects Radon risks Testing and Remediation

4. What is Radon? Natural Radioactivity 222 86 Rn Invisible, odorless, colorless, tasteless Only gas in 238 U decay chain 220 Rn from 232 Th has 55s t 1/2

5. What is Radon? Radon Gas 50 minutes 26.8m

6. What is Radon? Natural Radioactivity Source: http://energy.cr.usgs.gov/radon/DDS-9.htmlhttp://energy.cr.usgs.gov/radon/DDS-9.html

7. What is Radon? Stanley Watras Limerick Nuclear Power Plant, Christmas 1984 Set off radiation alarm bells Home basement Rn ~ 100 000 Bq m -3 Risk equivalent smoking 135 packs of cigarettes per day Designed to detect radiation on workers leaving…Watras was entering!

8. What is Radon? 1988 EPA orders every home tested

9. What is Radon?

10. Radon is a gas It is naturally occurring You cannot see or smell it It enters buildings from the soil via diffusion (concentration gradient) Uranium Radium Radon 1,600 years 4.5 billion years

11. Question Radon is said to be a daughter of radium-226, polonium-218 is a daughter of radon. Why are these not called sons? Radon decay products (RDP’s) continue to decay giving birth to new daughters (progeny). Indeed these RDP are the real culprits in the radon story!

12. What is Radon? Stack Effect Warm air rises and escapes home Pressure difference inside-outside Replacement air drawn in from below Increases with wind speed http://www.cornwallradon.co.uk/page21.html Stack effect enhances Rn movement

14. What is Radon? Spatial Distribution Radon enters from beneath foundation and travels upward Diluted with outdoor air infiltrating building 10 < 5 5-6

15. Health Effects Radon Gas Progenies (‘daughters’) build up in confined space –are breathed in, stick to surface of airways and emit α-particles

16. Radon Progeny 218 Po and 214 Po deliver the radiologically significant dose to the respiratory epithelium Lead-210 Polonium-214 Bismuth-214 Lead-214 Polonium-218 Radon-222 β, γ α,γα,γα,γα,γ α,γα,γα,γα,γ α,γα,γα,γα,γ Lead-206 Polonium-210 Bismuth-210 β, γ 22 yrs 4 day 3 min 27 min 20 min 0.2 ms 5 day 138 day Stable α,γα,γα,γα,γ

17. Health Effects Alpha  Decay 4 He Nucleus Ejected from 222 Rn Nucleus +2 He + Po 4 He + 218 Po + + + + + + + + + Radon - 222

18. alpha particle Highly energetic α, β particles rip through tissue causing cellular and genetic damage

19. Health Effects Interaction with DNA Highly radioactive particles adhere to lung tissue, where they can irradiate sensitive cells Radiation can alter the cells, increasing the potential for cancer Double Strand Breaks + ionize water to produce free radicals

20. NCRP 93 (1987) Natural (mrem) Radon200 Cosmic 27 Terrestrial: -external 28 -internal 39 Artificial (mrem) -Diag. X-rays39 -Nuc. Med.14 -Consumer Pro.10 -Other~1 TOTAL ~360 Radon delivers > 50% radiation dose

21. Radon Risks Radon Levels http://energy.cr.usgs.gov/radon/georadon/2.html GW > Soil > Indoor Air > Outdoor Air Outdoor?

22. Radon Risks Average Rn concentration inside a home 1 pCi L -1 Roughly 2 decays per minute 1 Working Level (WL) = 100 pCi L -1 (defined for no ventilation or walls) Effect of removal can be taken into account by x2 WL = 200 pCi L -1, thus 1 WL = 200 pCi L -1 at home WL = q Rn / 200 e.g. 1 pCi L -1 = 0.005 WL

23. Question Convert pCi L -1 to dpm L -1 1 Ci = 3.7 x 10 10 dps 60 secs in 1 minute 1 pCi = 0.037 dps x 60 = 2.22 dpm

24. Health Effects Group A Carcinogen Radon is ranked as a Group A carcinogen –Highest ranking for cancer potential –Known to cause lung cancer in humans –Tobacco smoke and tobacco products in same category Long-term exposure increases chances –Risk of lung cancer in normal life = 1-2 % (10-20 in 1000) –Risk of lung cancer at 1 pCi = + 0.3-1.3% (3-13 in 1000)

26. Health Effects Epidemiology ALA, AMA and Surgeon General all recommend reducing indoor Rn 15,000 – 22,000 deaths a year Epidemiology confirmed by NAS, WHO, NCRP Combined effects of Rn and smoking particuarly dangerous 2 nd hand smoke!

27. Health Effects Human Studies How do we know radon is a carcinogen? NCI study examined 68,000 uranium miners Miners die at a rate 5 x general population

28. Dose (rem) Adverse Health Effects Atomic Bomb Survivors Medical Patients Observed Effects ? ? ? Underground Miners Linear No threshold

29. Health Effects Biological Effects of Ionizing Radiation (BEIR) VI (1999) Risk estimates based primarily on radon-exposed miners Est. 15,000 – 22,000 lung cancer deaths each year in the U.S. from residential exposure 10-15% of all lung cancer deaths in US (150,000) Confirms 2 nd leading cause

30. Health Effects Comparing Radon Related Cancer 0 2000 4000 6000 8000 10000 12000 14000 16000 18000 20000 Annual U.S. Cancer Deaths Lung Cancer (radon) Liver Cancer Brain Cancer Stomach Cancer Melanoma Oral Cancer Gallbladder Cancer Bone Cancer

31. Health Effects How Radon Compares To Other Causes Of Death Lower estimate Drunk Driving DrowningsFires/Burns Air Transportation Radon Upper estimate Source: U.S. EPA’s Home Buyer’s and Seller’s Guide (Radon: National Academy of Sciences, Non-radon: National Safety Council)

32. Health Effects Radon and Smoking Darby et al., 2004

33. Question Convert pCi L -1 to Bq m -3 1 pCi L -1 x 1000 L m -3 = 1000 pCi m -3 1000 pCi m -3 x 3.7 x 10 10 Bq / Ci = 1 x 10 -9 Ci m -3 x 3.7 x 10 10 Bq / Ci = 37 Bq m -3

34. Health Effects Radon Risks Comparing Rn cancer rates to rates for smokers 20x Turko, 2002

35. Basement level

36. Radon-222 Zone 1: > 4 pCi/L (red) Zone 2: 2-4 pCi/L (orange) Zone 3: < 2 pCi/L (yellow) Based on indoor measurements, geology, aerial radioactivity, soil parameters and foundation type

37. End Review

38. Testing and Remediation Frequencies of 222 Rn in US Homes Radon levels depend on: Radon strength in soil Soil porosity Building to soil pressure difference Building ventilation rate Openings into the soil

39. Testing and Remediation Frequencies of 222 Rn in US Homes 8 million homes

40. Types of Measurement Continuous Integrated long and short term Multiple Single 1-7 day – ‘screening’ All rely on measurement of emitted radiation

41. Testing and Remediation Testing Alpha Track Photovoltaic Alpha-track Sensor Charcoal

42. Testing and Remediation Testing Alpha Track Alpha-tracks are plastics - microscopic radiation tracks after chemical treatment Magnified only 100 times 3 months at EPA Action Level of 4 pCi/L

43. These are pits in CR-39 plastic made by alpha particles. If they can make these pits in plastic, imagine what they can do to your DNA

44. Testing and Remediation Testing Sun-Nuclear Photo-diode – EPA verified continuous monitor Detects radon’s α-particle with 5.590 MeV energy. Works by measuring the voltage change across an P-N semiconductor bridge.

45. Factors Affecting the Emission of Radon Frost, rain, asphalt caps soil – stack effect exerted on larger area Wind

46. Factors Affecting the Emission of Radon What interpretation can you provide for the data in Fig. 1?

47. Factors Affecting the Emission of Radon Concentration varies continuously High in winter Low in summer

48. Testing and Remediation Radon Mitigation Active Soil Depressurization (ASD) –Creates a vacuum beneath the foundation Caulking and sealing Ventilation http://www.radon-services.com/animations/animation.htm

49. Testing and Remediation Passive System Large gravel beneath slab Polyethylene soil-gas retarder between slab and gravel Sealing and caulking Vent pipe running between sub-slab gravel and roof Junction Boxes (to power fan and warning device, if needed)

50. Key Findings Studies of uranium miners implicated radon as a known cause of lung cancer in humans Recent residential studies have provided direct evidence of increased lung cancer risk due to radon Suggest radon may play a role in 10% of all lung cancer deaths Nearly ¾ of radon-associated deaths occur among smokers Radon is an avoidable risk

51. Rebuked http://www.seered.co.uk/radon_newsci.htm http://removeradon.com/articles.htm

52. Further Reading Cothern (1999) Indoor Air Radon. Environmental Geochemistry and Health, Vol. 21, No. 1, pp. 83-90. Darby S., Whitley E., Silcocks T., Thakrara B., Green B.M.R., Lomas P.R., Miles J.C.H., Reeves G., Searn T. and Doll R., (1998) Risk of lung cancer associated with residential radon exposure in South - West England: A case-controlled study. British Journal of Cancer, Vol. 78, No. 3, pp. 394-408. Hess C.T., Weiffenbach, C.V., and Northon, S.A. (1983) Environmental radon and cancer correlations in Maine. Health Physics, Vol. 45, No. 2, pp. 339-348 Krafthefer B. (1984) Measurements of radon decay products in residential environments, Ashrae Journal - American Society of Heating, Refrigeration and Air-Conditioning Engineers, Vol. 26, No. 5, pp. 55. Harley N.H. (1984) Radon and lung cancer in mines and homes, New England Journal of Medicine, Vol. 310, No. 23, pp. 1525-1527. Joyce C., Kenward M. and Pearce F. (1986) Perils in the all-American home, New Scientist, Vol. 110, No. 1511, pp. 22-23. Pearce F. (1987) A deadly gas under the floorboards, New Scientist, Vol. 113 (1546), pp. 33-35. Oge M. (1994) The US environmental agency`s strategy to reduce risks of radon, Radiation Protection Dosimetry, Vol. 56, No. 4, pp. 343-354. Phillips P.S. and Denman A.R. (1997) Radon: a human carcinogen. Science Progress, Vol. 80, No. 4, pp. 317-336. Phillips P.S., Denman A.R., and Barker S. (1997) Silent, but deadly. Chemistry in Britain, Vol. 33, No. 1, pp. 35-38.

53. Books Brookins, D.G. (1990) The Indoor Radon Problem. Columbia University Press. Cole, L.A. (1994) Element of Risk: The Politics of Radon. Oxford University Press. Cothern, C.R., and Smith, J.E Jr. (1987) Environmental Radon. Springer. Durrani, S.A., and Radomir, I. (1997) Radon Measurements by Etched Track Detectors : Applications in Radiation Protection, Earth Sciences and the Environment. World Scientific Publishing Company. National Research Council (1989) Health Effects of Exposure to Radon. BEIR IV. National Research Council. Nazaroff, W. and Nero, Jr., A. (1988) Radon and its Decay Products in Indoor Air. Wiley, New York.

54. Modeling Radon Exposure Box Model Q = S τ q = Q / V = S τ / V Source S Sink L V QqQq Q = quantity q = concentartion

55. Modeling Radon Exposure Sources and Sinks Sources, S Rn = 0.01 – 10, mean = 0.5 pCi L -1 h -1 Background concentration, q 0 Rn = 0.2 pCi L -1 Residence time of air in the home, τ v Background gas ventilation rate (per unit voume), S v = Q 0 = q 0 Rn V V τ v τ v Sinks, Ventilation loss rate, L v = q Rn / τ v (q Rn = Rn concentration inside) Decay loss rate, L d = q Rn / τ Rn ( τ Rn = half-life = 91 hrs) Steady-state: S Rn + S v = L v + L d

56. Question S Rn + S v = L v + L d S Rn + q 0 Rn / τ v = q Rn / τ v + q Rn / τ Rn Rearrange to find q Rn q Rn = q 0 Rn + τ v S Rn 1 + τ v / τ Rn

57. Modeling Radon Exposure Radon Concentration S Rn + S v = L v + L d S Rn + q 0 Rn / τ v = q Rn / τ v + q Rn / τ Rn q Rn = q 0 Rn + τ v S Rn 1 + τ v / τ Rn Usually simplified:q Rn ≈ q 0 Rn + τ v S Rn (denominator = 1) Since: q 0 Rn = 0.2 pCi L -1, S Rn = 0.01 - 10, mean = 0.5 pCi L -1 h -1 and τ v = 1 hr q Rn = 0.7 pCi L -1 Rn concentrations are clearly dependent on source and ventilation!

58. Modeling Radon Exposure Radon Concentration q Rn ~ q 0 Rn + τ v S Rn With fast ventilation τ v = 0, q Rn ≈ q 0 Rn (depends on outside air conc.) With no ventilation τ v = ∞, q Rn ≈ τ Rn S Rn (depends on source and t 1/2 )