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

Yuanming Guo, Paul Dahlen, Paul C. Johnson

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


Controlled pressure method (CPM) testing is a building-specific diagnostic tool for vapor intrusion (VI) pathway assessment which offers advantages over traditional pathway assessment approaches. By manipulating the building pressure conditions, the CPM creates the worst-case VI impact and provides rapid insight into the type of vapor source(s). The primary barrier to general acceptance and use of this tool is the need for definitive guidance on test design parameters, such as the indoor-outdoor pressure difference (or exhaust fan flow rate), CPM test duration, exhaust fan location, and air sampling location(s) and conditions. This study focused on a systematic evaluation of each of these factors, which then led to the formulation of proposed CPM testing guidelines. The results suggest that CPM tests should be conducted with both negative and positive pressure indoor-outdoor differentials of about 10-15 Pa, and the tests should last for at least nine indoor air exchanges for negative pressure difference testing and four indoor air exchanges for positive pressure difference testing. Although exhaust fan intake sampling is sufficient to provide critical information to assess impacts during negative pressure testing, adding room-specific indoor air sampling to both negative and positive pressure difference testing can provide insight into vapor entry locations and indoor source contributions.

Original languageEnglish (US)
Pages (from-to)7117-7125
Number of pages9
JournalEnvironmental Science and Technology
Issue number12
StatePublished - Jun 16 2020

ASJC Scopus subject areas

  • General Chemistry
  • Environmental Chemistry


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