MAMF_with 1-21 Revisions

MAMF/MALB Companion Guidance 2021 Section 2 Guidance to Building Managers 6 Results from the EARTH Study: Partial Testing of Multifamily Buildings Will Misrepresent Radon “Evaluating and Assessing Radon Testing in Housing with Multifamily Financing” (EARTH) was a HUD-funded Healthy Homes Technical Study led by Health Research Inc. for the New York State Department of Health with assistance from the National Center for Healthy Housing. The primary aim of the study was to develop an evidence-based, statistically sound protocol for measurement professionals to correctly characterize a multifamily building’s radon level that is sufficiently protective of occupant health without being unduly burdensome to transactions or property owners. The below table presents the probability of missing a unit with a radon level above the EPA action level, based on the % of units sampled, according to the analysis of data for units in 276 multifamily buildings in the US. These data indicate, across building sizes, that to characterize radon levels correctly in multifamily buildings with up to 20 ground-contact units, i.e., achieve 95% confidence that no units in the building have radon ≥4 pCi/L, 100% testing is required. For the vast majority of multifamily building sizes, all ground-contact units in the buildings should be tested for radon. Average probability (%) of partial sampling missing a unit in a building* with>4 pCi/L with various sampling percentages. Number of ground contact units Number of buildings 10% sampled 25% sampled 50% sampled 75% sampled 90% sampled 05-06 45 58 34 19 4.7 0.0 † 07-08 71 55 36 15 4.6 0.0 † 09-10 40 65 39 24 8.5 3.8 11-12 37 52 41 21 8.1 2.8 13-14 14 51 35 20 7.4 2.2 15-16 20 47 32 15 5.0 1.3 17-18 15 59 39 21 8.1 1.9 19-20 12 69 46 23 8.9 2.6 21-26 22 52 34 18 6.7 2.3 All 276 58% 38% 19% 6.5% 1.7% *Ground contact units only. Includes buildings with at least one unit ≥4 pCi/L. † Note that for 90% sampling all units are tested for buildings with 9 or fewer units. The work that provided the basis for this document was supported by funding under cooperative agreement # NYHHU0038-17 from the U.S. Department of Housing and Urban Development’s Office of Lead Hazard Control and Healthy Homes. The substance and findings of the work are dedicated to the public. The author and publisher are solely responsible for the accuracy of the statements and interpretations contained in this presentation. Such interpretations do not necessarily reflect the views of the Government.