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EnviroGroup Limited   Vapor Intrusion News - November 2004
In This Issue:
 •  Colorado Issues Draft Indoor Air Guidance
 •  San Diego County adds Naphthalene to Vapor Risk 2000
 •  Colorado Finalizes New TCE Action Levels
 •  Oregon Screening Model for Heating Oil Sites
 •  Information Source on Household Products
 •  EPA Issues Final Report on the Neurotoxicity of PCE
 •  The Importance of Background Evaluations

Featured Links:

 •  List of Indoor Air Testing Labs
 •  PPB - UG/M3 Unit Conversion Tool
 •  Vapor Intrusion Website Links
Colorado Issues Draft Indoor Air Guidance
The Colorado Department of Public Health and Environment (CDPHE) has issues draft Indoor Air Guidance for public comment. The draft guidance is intended to result in more consistent approaches to vapor intrusion evaluations and is based on CDPHE experience at a number of vapor intrusion sites. While the guidance emphasizes flexibility and line of evidence approaches, it states a preference for indoor air sampling. Unlike the EPA vapor intrusion guidance, CDPHE's draft guidance includes procedures for evaluating the extent of impacts and mitigation. CDPHE generally defers to OSHA PELs in occupational settings where workers have "voluntarily accepted the known risks associated with exposure". CDPHE will consider comments received between November 15 and December 31, 2004.
CDPHE draft indoor air guidance

San Diego County adds Naphthalene to Vapor Risk 2000
San Diego County has revised its Vapor Risk 2000 model to include the new California slope factor for Naphthalene (August 2004). Because "naphthalene is present in all petroleum fuels", San Diego County is now requiring analysis for naphthalene at fuel release sites. The following website provides links to the San Diego County Vapor Risk 2000 model, the California Office of Environmental Health Hazard Assessment (OEHHA) cancer slope factor for naphthalene, and other websites with information on naphthalene.

San Diego County Vapor Risk Assessment 2000

Colorado Finalizes New TCE Action Levels
On August 20, 2004 the Colorado Department of Public Health and the Environment (CDPHE) announced its adoption of an interim policy regarding TCE in indoor air. This policy requires mitigation if indoor air concentrations of TCE exceed 1.6 ug/m3, based on a 10-4 excess cancer risk level and EPA's provisional TCE slope factor. The policy also requires further study when a concentration between 1.6 and 0.8 ug/m3 is measured in indoor air. Mitigation is not required if a lines of evidence evaluation demonstrates that the TCE is due to background sources. Although mitigation and monitoring are not typically required at TCE concentrations below 0.8 ug/m3, a no further action approval requires a demonstration that TCE concentrations are below 0.016 ug/m3 or background, if higher (go to www.envirogroup.com/publications.htm for two papers presenting background TCE data). The new TCE policy, including CDPHE's general policy on use of toxicity values, can be found at the link below. CDPHE's response to public comments on the proposed TCE action levels is also provided at the same site.

Colorado New Policies on Use of Toxicity Values and TCE

Oregon Screening Model for Heating Oil Sites
The Oregon DEQ Heating Oil Tank program has developed a spreadsheet model that estimates site-specific screening levels for volatilization from soil to indoor air at heating oil tank sites. The model is "offered for public use without guarantees or support by the Department." DEQ also states that it "may decide to use risk-based screening levels other than those generated by this spreadsheet."

Oregon Heating Oil Program Screening Model

Information Source on Household Products
The National Library of Medicine has a database with information on common household products. The database includes material safety data sheets, which sometimes identify the principal ingredients in the products. The database may be useful in investigating background sources of indoor air contaminants.

National Library of Medicine Database

EPA Issues Final Report on the Neurotoxicity of PCE
In July EPA released the final report “Summary Report of the Peer Review Workshop on the Neurotoxicity of Tetrachloroethylene Discussion Report”. This report can be found at:

PCE Neurotoxicity Report

The Importance of Background Evaluations
EPA's provisional slope factors for TCE can result in very low indoor air target levels, as found in the Region 3 RBC tables (0.016 ug/m3), the draft EPA subsurface vapor intrusion guidance (0.022 ug/m3), and in many state programs. Unfortunately, recent studies (go to link below) have shown that background levels of TCE in residential homes are much higher than these target levels, with median or mean values of about 0.15 ug/m3 and 95 percentile concentrations of 0.7 ug/m3. We have measured values in the thousands of ug/m3 range in some homes (e.g., due to gun cleaner use). Therefore, it is critical that agencies and responsible parties recognize the existance of background sources and provide processes that allow background to be considered when setting action levels and mitigation performance standards. Two papers providing recent data on background levels of TCE and other solvents in residential settings are available on the link below.

Link to Background Papers


This newsletter is issued periodically to provide our readers with information on new regulatory and technical developments in the rapidly changing field of vapor intrusion. While every effort is made to ensure that the information and links presented in this newsletter are accurate at the time of publication, they are presented for general information purposes only. Users should independently verify the accuracy and applicability of this information and seek professional advice for any specific sites or purposes. Articles on or links to any document or website do not imply endorsement of that document or website by EnviroGroup. Copyright EnviroGroup Limited 2003. 7009 S Potomac Street, Centennial, CO 80112. Telephone (303) 790-1340.

Please contact us if you have any questions about the topics presented in this newsletter, or vapor intrusion in general. More information about EnviroGroup Limited, including several useful links to vapor intrusion websites, is available at:  EnviroGroup Limited - Vapor Intrusion Solutions
5670 Greenwood Plaza Blvd, Suite 540 | Greenwood Village, CO 80111 | 303-790-1340
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