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General Radon Information

There is no known safe level of exposure to radon. EPA strongly recommends that you fix your home if your test shows 4 picocuries (pCi/L) or more. If your test shows between 2 and 4 pCi/L, consider Mitigation.

This guidance offers strategies for testing your home for radon and discussions of what steps to take after you have tested, discussions of the risk of radon and radon myths. (Note: The current version reflects corrections to links and contact information.)

You have tested your home for radon, but now what? This guidance has been specifically designed for people who have tested their home for radon and confirmed that they have elevated radon levels — 4 picocuries per liter (pCi/L) or higher. Know what to look for when selecting a qualified contractor to reduce the radon levels in your home, determine an appropriate radon reduction method and maintain your radon reduction system.

This booklet is intended for anyone who is buying or selling a home, real estate and relocation professionals, home inspectors and others.


The purpose of this map is to assist National, State and local organizations to target their resources and to implement radon-resistant building codes. This map is not intended to be used to determine if a home in a given zone should be tested for radon. Homes with elevated levels of radon have been found in all three zones. All homes should be tested regardless of geographic location.


(Click bold headings to download information)


The following documents are sources of additional radon mitigation information

  • ASTM E2121-13, Standard Practice for Installing Radon Mitigation Systems in Existing Low-Rise Residential Buildings, ASTM International, West Conshohocken, PA, 2009, 

  • EPA Training Manual, "Reducing Radon In Structures (Third Edition)," January 1993.

  • "Radon Reduction Techniques for Detached Houses, Technical Guidance (Second Edition)," EPA/625/5-87/019, January 1988.

  • "Application of Radon Reduction Methods," EPA/625/5-88/024, August 1988.

  • "Indoor Radon and Radon Decay Product Measurement Device Protocols," EPA 402-R-92-004, July 1992.

  • "Protocols for Radon and Radon Decay Product Measurements in Homes," EPA 402-R-92-003, June 1993.

  • "A Citizen's Guide To Radon (Second Edition)," EPA 402-K92-001, May 1992.

  • "Consumer's Guide to Radon Reduction," EPA, 402-K92-003, August 1992.

  • "Home Buyer's and Seller's Guide to Radon," EPA 402-R-93-003, March 1993.

  • "ASHRAE Standard 62-1989," Appendix B, Positive Combustion Air Supply.

  • "National Gas Code," Appendix H (p.2223.1-98), 1988, Recommended Procedure for Safety Inspection of an Existing Appliance Installation.

  • "Chimney Safety Tests User's Manual," Second Edition, January 12, 1988, Scanada Shelter Consortium, Inc., for Canada Mortgage and Housing Corp.

  • OSHA "Safety and Health Regulations for Construction, Ionizing Radiation," 29 CFR 1926.53.

  • OSHA "Occupational Safety and Health Regulations, Ionizing Radiation," 29 CFR 1910.96.

  • NIOSH "Guide to Industrial Respiratory Protection," DHHS (NIOSH) Publication No. 87-116, September 1987.

  • NCRP "Measurement of Radon and Radon Decay Daughters in Air," NCRP Report No. 97, November 1988.

  • EPA Handbook, "Sub-Slab Depressurization for Low Permeability Fill Material," EPA/625/6-91/029, July 1991.

  • "Radon Reduction Techniques for Existing Detached Houses, Technical Guidance (Third Edition) for Active Soil Depressurization Systems," EPA/625/R-93-011, October 1993.

  • "Comparison of Two Standards for Radon Mitigation in Existing Low-Rise Residential Buildings: ASTM1s E 2121 and EPA's RMS", Philip H. Anthes & William J. Bell, August 28, 2001. 

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