AARST_Radon_Reporter_Q32025_Single

THE RADON REPORTER | 13 The Business Case for Radon Testing in Multifamily Lending Is Multi-Faceted The incremental per-unit cost of 100% ground contact unit radon testing is at most 31 cents per unit per month over a 20-year loan at 4% interest. • Based on IEA’s analysis of the testing requirements for a typical property with an average of 155 units of which, per the standard, 100 ground contact and upper floor units would be tested at the high-end cost of $80 each, the monthly cost per unit ranges from 20 cents per unit per month to 31 cents per unit per month over the life of a 20-year loan at 4% interest (and less for shorter-term loans). ix • Mitigation costs $2.35 - $3.91 per unit per month over the life of a 20-year loan period at 4% interest. x In December 2020, after a three-year review and extensive public comments, HUD multifamily lending eliminated the 25% threshold to require testing 100% of ground contact units consistent with the industry consensus standard. • HUD’s decision was based on data from the Antonio Neri paper, “Evaluation of percentage- based radon testing requirements for federally funded multi-family housing projects” xi and the HUD-funded New York State Department of Health study, “Evaluating and Assessing Radon Testing in Housing with multifamily federal nancing (EARTH Study).” xii • The EARTH study team analyzed 100% ground contact test results for 687 multifamily buildings encompassing 7,892 dwelling units and determined that testing only 25% of ground contact units (HUD’s protocol since 2013) had a 38% chance of missing at least one unit with a high radon level. Number of ground contact units Number of buildings 10% sampled 25% sampled 50% sampled 75% sampled 05-06 45 58% 34% 19% 5% 07-08 71 55% 36% 15% 5% 09-10 40 65% 39% 24% 9% 11-12 37 52% 41% 21% 8% 13-14 14 51% 35% 20% 7% 15-16 20 47% 32% 15% 5% 17-18 15 59% 39% 21% 8% 19-20 12 69% 46% 23% 9% All 276 58% 38% 19% 6.5% Inspecting 10% of ground contact units fails to identify homes with high radon levels. • The usual multifamily environmental assessment process, based on common QC procedures in manufacturing and other industries, has involved inspecting (or sampling) 10% of units under the theory that 10% is su ciently representative. • Variations in conditions below slabs and crawl spaces, building tightness, HVAC system operation, the stack e ect, intrusion pathways present, and other building science realities cause signi cant di erences in radon levels from one dwelling unit to the next within the same building, and from one building to the next on the same property. • Since radon is naturally occurring in the ground, moves around opportunistically, and therefore is not present throughout, or consistently across the footprint of, a multi-unit structure, the EARTH Study found that it’s necessary to test all ground contact dwelling units. Testing only 10% of ground contact units, the Fannie Mae and Freddie Mac protocol, has a 58% chance of missing a high-radon unit. xii Inadequate sampling creates liability risk for properties and cancer risk for occupants. Liability against the property and its owners can arise from a claim under: • the warrant of habitability in landlord-tenant law • unreasonable risk of serious harm to occupants’ current or future health xiv • deliberate indi erence • neglecting to follow known standards. xv AVERAGE PROBABILITY (%) OF PARTIAL SAMPLING MISSING A UNIT IN A BUILDING WITH RADON LEVEL >4 PCI/L AT VARIOUS SAMPLING PERCENTAGES (Source: EARTH Study)