Radon Reporter March 2022

18 | Mach 2022 MITIGATION ventilation rate of the basement can be determined by dividing the additional CFM by the total of the initial radon divided by the final radon minus 1. The natural ventilation plus the added ventilation is the total ventilation that produces the lower radon levels. All of this assumes the total radon is coming from the concrete. The test indicates a 100 CFM HRV would induce a 1.2 pCi/l basement. Over eight days of testing, it is possible the basement ACH varied from 0.13 to 0.085. After this testing, the owner installed a Fantech VHR150 HRV that produced an additional 90 CFM of outdoor air and a steady basement radon level of 1.27 pCi/l (Figure 4). Unfortunately, we do not have much data on radon flux from concrete in different areas of the country or know its frequency or significance. What is a given is new homes are being built tighter and often without any additional mechanically provided outdoor air. FIGURE 3 FIGURE 4