USGBC follows the EPA recommendations on radon testing. Please see www.epa.gov/radon/pubs/citguide.html for details. EPA guidance includes 3 steps: 1) Take a short-term test. If the result is 4 pCi/L or higher, go to step 2; 2) Follow-up with either a long-term test or a second short-term test. 3) If you followed up with a long-term test and the result is 4pCi/L or more, then mitigation is required; if you followed up with a second short-term test and the average of the two tests is 4 pCi/L or higher, then mitigation is required. If a mitigation system is required and installed, the project must undergo testing following the steps above to confirm that the mitigation system is operating as needed. If two short-term tests report 4 pCi/L or more, consult a radon expert to fix or improve the radon mitigation system, then repeat all previous steps again.Further EPA guidance:
Updated 10/1/13 for rating system applicability.