December 12th, 2017
We have done a detailed study comparing indoor radon concentrations among single-family dwellings in Colorado Springs that were mitigated prior to the completion of construction and similar buildings that were mitigated after construction. There appears to be evidence which indicates that “preconstruction” mitigation is more effective at lowering indoor radon concentrations than “post-construction” mitigation. A total of 102 owners of single-family dwellings, in two different areas within the city, agreed to participate in the study. Thirty-nine homes formed the preconstruction mitigation category (with 14 of these homes having only passive systems), 24 had been mitigated after the construction, and the final 39, chosen as a control group, had never been mitigated but shared similar soil and surficial geological features with the mitigated homes (including distance to nearby faults). Eighty-nine homeowners successfully completed the test. All of these houses were tested over the same 48-hour period, under closed-house conditions, thereby controlling the variables of weather and, to some extent, occupants’ usage. By analyzing the data obtained, we can conclude that there is a statistically significant difference in post-mitigation indoor radon concentrations (as measured by simultaneous charcoal screening tests) between the preconstruction and the post-construction mitigated homes. The preconstruction category exhibited the lower radon average, although both mitigation categories had averages below 4.0 pCi/L. Such a conclusion could have an impact on current mitigation practices, especially as they pertain to new housing construction. Esthetics, installation costs, and operating costs of the two mitigation techniques (pre- and post-construction) are also discussed herein.