Table 3: Radon Concentrations in the US and Colorado (1) and the Risks Associated with Radon Exposure

1. Radon concentration is in picocuries/liter. US averages can be found on Basic Facts about Radon (Rn). Colorado radon levels are from US Geologic Survey, Colorado Department of Health, Radiation Division, Open File Report 91-4.
2. Table 3-10 in Health Effects of Exposure to Radon, BEIR VI (National Research Council, Washington DC, 1998) presents the estimated number of lung cancer deaths in the U.S. in 1993 attributable to indoor radon progeny exposure. The annual risk of lung cancer per American was calculated by first averaging the results of the two models the committee preferred and then dividing the result by 258,900,000, the US population in 1993. Multiplying this result by 1,000,000 gives the lung cancer deaths per million people. This risk was then scaled for other radon concentrations found in Colorado -- this scaling assumes that the shapes of the distributions are comparable.
3. Lifetime risk is annual risk multiplied by 70 years.
4. Borak, T.B. and S.A. Baynes, 'Continuous Measurements of Outdoor 222Rn Concentrations for Three Years at one Location in Colorado,' Health Physics, April 1999, Vol. 76, No. 4, 418-420. 37 Bq/m3 = 1 mSv
5. Two measurements at the same location. Environmental Radon Measurements Report, Western Regional Radon Training Center, Colorado Springs, Co. May 15, 1998.
6. Short term indoor radon measurements in Jefferson and Boulder counties illustrate the variability in radon concentrations. A first floor measurement in Boulder county found 1.5 pCi/L of radon and a similar measurement in Jefferson county found 1.9 pCi/L. However, in the basements of those same buildings the radon was recorded at 1.2 pCi/L in Boulder county, but 13 pCi/L in Jefferson county. Environmental Radon Measurements Report, Western Regional Radon Training Center, Colorado Springs, Co. May 15, 1998.