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Pacific Southwest, Region 9

Serving: Arizona, California, Hawaii, Nevada, Pacific Islands, Tribal Nations

Regional Science Council Activities

Innovation for Testing Indoor Air
Video Summary: A RARE Opportunity to Improve Vapor Intrusion Investigations

The Regional Applied Research Effort (RARE)

The Regional Applied Research Effort (RARE) can be used to address any type of issue or problem that a region identifies as a high priority research need which the Office of Research and Development (ORD) has the necessary expertise and capability to address. Special consideration will be given to research proposals that can be linked to decisions leading to measurable environmental outcomes. Resources are divided equally among the regions and each region is responsible for nominating the particular research project(s) to be funded with these resources. Project proposals are accepted once a year and are reviewed for funding under the Program. The highest rated projects in each Region are selected for funding based upon merit and available funding.

Recent Region 9 RARE Projects and Funding Levels
Project Title Start Date Status RARE$
Chemical Characterization of Ambient Coarse Particulate Matter in Rural Areas of Arizona Impacted by Significant Population Growth 2009 Active $58,700
Development of Practical Approaches to Investigate Vapor Intrusion 2008 Active $76,435
Testing for the Control Efficiencies of Agricultural Best Management Practices 2007 Active $100,000
Green Cleanup Practices: Using Renewable Energy and Cleaner Diesel Equipment at Waste Cleanup Sites and Traffic Exposure 2006 Active $65,000
How Vulnerability Indicators Affect the Association between Adverse Birth Outcomes and Air Pollution and Traffic Exposures 2006 Active $89,000
Preparation of Updated Design and Performance Guidance for Municipal Wastewater Stabilization Pond (Lagoon) Systems: A Multi-Regional Project 2006 Active $70,000
Determination of Protective Dietary Selenium Benchmarks to Assist in the Development of Wildlife Criteria for the San Francisco Bay-Delta 2005 Active $30,000
Methods Development and Preliminary Application for Leptospira Spirochetes 2005 Active $105,000
Testing of Dust Suppressants for Water Quality Impacts 2005 Active $80,000

Development of Practical Approaches to Investigate Vapor Intrusion

EPA Region 9 staff, working with the Office of Research and Development (ORD), assessed several innovative methods to evaluate vapor intrusion into indoor air. Vapor intrusion, which is the migration of subsurface volatile organic compounds (VOCs) and other chemicals into indoor air, has emerged as a priority contaminant pathway at hazardous waste sites nationwide.

Alana Lee, Mathew Plate, and Kathy Baylor teamed up with ORD researchers and were awarded a Regional Applied Research Effort (RARE) grant for $104,000 to evaluate several new practical methods to assess the vapor intrusion pathway into buildings. Three techniques were investigated: (1) using radon sample data as a surrogate for determining VOC vapor intrusion; (2) using building pressure differential to assess the potential for vapor intrusion; and (3) using sorbent-based methods for longer time-integrated measurement (days to weeks) of indoor air VOCs.

The project team has completed all three phases of the project. The first two were performed at a former military housing complex near San Francisco Bay. The third phase focused on the most promising practical techniques for assessing vapor intrusion into commercial buildings.

The RARE vapor intrusion project included the investigation of sub-slab soil gas concentrations. Sub-slab soil gas data is one line of evidence commonly used to determine the potential for subsurface vapor intrusion into an overlying building at a site. Soil gas samples from immediately beneath a building's concrete slab are analyzed for volatile organic compounds (VOCs) and when compared to empirical attenuation factors, can help assess the potential for vapor intrusion into a building exceeding a risk-based health screening level. Download the variability report (PDF) (3 pp, 253K).

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