This report presents technical information about sites in the U.S. that have been investigated for vapor intrusion. The primary focus of the report is the evaluation of concentrations of chlorinated Volatile Organic Compounds (VOCs) in and underneath residential buildings based upon EPA's vapor intrusion database as of 2010. The technical information provided in this report may be useful for regulators, responsible parties, and others assessing and managing vapor intrusion investigation programs. An erratum was issued on July 3, 2012 to correct Table 10.You will need Adobe Reader to view some of the files on this page. See EPA’s About PDF page to learn more.