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Resources on Acceptable Indoor Radon Concentrations

A list of credible sources concerning acceptable indoor radon concentrations are listed below:

1. NCRP, Exposures From the Uranium Series With Emphasis On Radon and Its Daughters – Report 77, National Council on Radiation Protection and Measurement, 1984.

The National Council on Radiation Protection and Measurement in their Report 77 established 0.04 WL as the amount of the concentration of radon and it's daughters that should be acceptable in nonoccupational occupied structures. Using the current 40% equilibrium assumption that would be 10 pCi/l. This was done in 1984 but it has not beerescindeded by NCRP. The recommendations of NCRP are widely utilizeded in radiation regulatory in the United States especially in the areas of medical uses of radiation.

2. International Commission on Radiation Protection, Website http://www.icrp.org, Statement On Radon, ICRP Ref 00/902/09, 2009

The ICRP in 2009 revised it's reference level recommendation for residential structures downward to 300 pCi/l. This would convert to 8 pCi/l of radon. The ICRP is one of the free world's most respected and leading radiation standard setting bodies.

3. EPA, "A Citizen's Guide To Radon," EPA 402-K02-006, revised September 2005. http://www.epa.gov/radon/pubs/citguide.html

The U.S. EPA has established an "Action Level" of 4 pCi/l for indoor radon. Unlike the two items above, EPA action level is not based upon radiation dose and risk, but is based upon EPA's belief that "the radon levels in most houses can be reduced to about 4 pCi/l." (Quote from notebook Radon Facts distributed to the states by the EPA Headquarters Radon Division in April 1993.)

4. World Health Organization, "WHO Handbood on Indoor Radon, A Public Health Perspective," 2009, http://www.who.int/ionizing_radiation/env/radon/en/index1.html

This WHO report states that a reference level i.e. action level of 100 Bq/m3 (2.7 pCi/l) is justified based upon in view of the latest scientific data on health effects of indoor radon and recommends that a nation's reference level be within the range of 100 Bq/m3 to 300 Bq/m3 (2.7 pCi/l to 8 pCi/l).

Another source would be IAEA Safety Series No. 115-1, International Basic Safety Standards for Protection against Ionizing Radiation and for the Safety of Radiation Sources, International Atomic Energy Agency, Viena. It contains a total dose limit for radon progeny of 4 WLM for the average of 5 years with no one year to exceed 10 WLM. But it combines home dose with the occupational dose so it is difficult to compare with a residential action level as used in the USA.

5. Health Physics Society's Perspectives and Recommendations on Indoor Radon

The Health Physics Society published “Perspectives and Recommendations on Indoor Radon”—its initial position statement on indoor radon—in October 1990. Since that time, the National Academy of Sciences has reevaluated the epidemiological data on underground miners and reviewed indoor radon epidemiological studies. The Academy published its findings in 1999 in its BEIR VI Report, “Health Effects of Exposure to Radon.” The U.S. Environmental Protection Agency (U.S. EPA) reevaluated its risk assessment in 2003. In addition, a significant amount of new information on residential radon studies has become available in the past few years. The position can be found at http://hps.org/documents/radon_position_statement.pdf.

6. ELI - Environmental Law Institute

the Environmental Law Institute has just updated its Database of State Indoor Air Quality Laws, to include state laws enacted through December 2009. The Database, which covers a wide variety of IAQ laws, lists the laws by state and provides a citation and short abstract for each law. In addition to the complete database, you can view sub-databases for mold, radon, and IAQ in schools. The database documents are available on the ELI website: http://eli.org/Program_Areas/indoor_environments.cfm.

ELI also has updated two documents in our series of Policy Updates. Healthy High Performance School Facilities: Developments in State Policy and Radon Control in New Home Construction: Developments in State Policy are both available on the above website.