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

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...

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Bibliographic Details
Published in:Environmental science & technology 2020-06, Vol.54 (12), p.7117-7125
Main Authors: Guo, Yuanming, Dahlen, Paul, Johnson, Paul C
Format: Article
Language:English
Subjects:
Air sampling
Design parameters
Diagnostic software
Diagnostic systems
Flow rates
Flow velocity
Indoor air quality
Indoor environments
Intrusion
Pressure
Test procedures
Vapor sources
Vapors
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Summary: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.
ISSN:0013-936X
1520-5851
DOI:10.1021/acs.est.0c00811