Determination of the radon potential of a building by a controlled depressurisation technique (RACODE)

Development and Validation of a Controlled Pressure Method Test Protocol for Vapor Intrusion Pathway Assessment

“…The daily-average indoor air TCE concentration during CPM testing only varied by about 2× during the 270+ days of building negative pressurization; therefore, the impact of weather conditions on CPM test results is not considered significant. This is also supported by one radon intrusion study, in which they suggested that radon concentration during building depressurization was “building-specific” and “weather-independent”.…”

“…In contrast, CPM testing conducted in a study building having highly variable indoor air grab sample results under natural conditions yielded relatively constant daily average results over nine months, and the CPM test results were similar to the maximum concentration measured under natural conditions. Based on results available to date, it also appears that negative pressure difference testing results are not significantly affected by weather conditions (e.g., wind and precipitation). ,, Thus, CPM tests need only be conducted once and for <24 h, and decision makers can reach conclusions about the presence of the VI pathway and impact quicker and more confidently with CPM testing than with conventional indoor air sampling under natural conditions. An additional advantage of CPM testing versus indoor air grab sampling is that indoor air sampling results can be confounded by unknown indoor air pollutant sources, while CPM testing can identify the presence of significant indoor sources. , …”

“…Although studies to date have shown the benefits of CPM testing for VI pathway investigations, the use of this diagnostic tool is still in its early stages and guidance is needed to ensure that it is practiced in a valid and consistent way. Based on CPM testing studies for radon − and VI risk assessment, ,,,,, basic CPM test design parameters include indoor–outdoor pressure difference (or exhaust fan flow rate), CPM test duration, exhaust fan location, and air sampling location(s) and protocol(s). In past studies, the indoor–outdoor pressure difference was typically controlled to about −5 to −10 Pa (indoor–ambient atmospheric pressure). ,, The CPM testing duration ranged from less than 8 h to almost 9 months. ,,,,, With respect to the sampling protocol, floor fan placement appeared to have noticeable impact on the efficiency of pressure control and the spatial distribution of indoor air pollutants in the USEPA study.…”