MALB_2014 with 1-21 Revisions

Conducting Measurements of Radon and Radon ANSI/AARST MALB-2014 with 1/21 Revisions Decay Products in Schools and Large Buildings 22 7.0 ACTIONS BASEDON TEST RESULTS 7.1 Action Level Guidance Countries worldwide have adopted a ction levels for radon exposures. The action level observed should comply with the guidance of the country, state or local jurisdiction of authority where the test is being conducted. U.S. Action Level. The following action level descriptions reflect guidance from the United States Environmental Protection Agency (EPA): • 4 pCi/L or greater ( ≥ 150 Bq/m 3 ) Fix the building. The higher the radon concentration, the more quickly action should be taken to reduce the concentrations. • Below 4 pCi/L (< 150 Bq/m 3 ) Consider fixing the building if test results indicate that radon concentrations are greater than half the action level , such as between 2 and 4 pCi/L (75 and 150 Bq/m 3 ). With observance that hazards from radon are virtually the same for radon concentrations that are near action level thresholds, it is noteworthy that the World Health Organization recommends limiting long-term exposures to less than 2.7 pCi/L (100 Bq/m 3 ). Whenmeasurement devices indicate concentrations lower than about 2.0 pCi/L (75 Bq/m 3 ), test data should normally be interpreted as being lower than the test device can accurately measure. 7.2 When Two Test Results Disagree 7.2.1 Acceptable When two test devices were deployed to test the same testing location, the average of the two test results shall be reported as the value used for determining needs for mitigation if: a) both test results are above the action level , or b) both test results are below the action level . 7.2.2 Where test results disagree on exceeding the action level When one test result is above the action level and the other test result is below the action level : a) Acceptable If the higher result is less than twice the lower result, the average of the test results shall be reported as the value used to determine if this location needs mitigation ; and b) Not acceptable If the higher test result is more than twice the lower test result: 1. For two collocated (side-by-side) tests conducted at the same time, a repeated collocated test for this location is required to obtain a valid measurement; and 2. For two short-term detectors deployed at different times in the same location, obtaining confirmation on whether or not mitigation is warranted requires additional testing unless it is decided to proceed with mitigation . This degree of uncertainty requires a precautionary stance to include that the higher test result shall be regarded as correct for making mitigation decisions unless further testing indicates otherwise.