Vapor intrusion continues to grow in prominence as an environmental concern and area of environmental regulation and litigation. On January 28, the EPA issued a Notice of Opportunity for Public Comment stating that it would accept public input on whether vapor intrusion should be included as a component of the Hazard Ranking System used to determine site placement on the National Priorities List (NPL) under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). Vapor intrusion occurs when subsurface chemical vapors migrate into buildings and other structures nearby. The cause of vapor intrusion is not always easy to identify, as it could occur from other chemicals present on-site. The EPA will evaluate all information collected (through both public comment and public listening sessions) before determining if it should issue a proposed rule. If the EPA does issue this rule, many more sites would likely be added to the NPL, particularly in urban areas. This is of particular concern for property owners of potentially emitting sites, as people living or working near the site would more than likely institute toxic tort lawsuits against the owners, and there has been litigation regarding whether vapor intrusion may present an “imminent and substantial endangerment” under the Resource Conservation and Recovery Act (RCRA), which has a citizen suit provision. Also, with the ASTM Standard Guide for Vapor Encroachment Screening on Property Involved in Real Estate Transactions having been revised in 2010, additional attention is being paid to vapor intrusion as an issue to be considered in due diligence for property and financing transactions. New York has stated that soil vapor intrusion evaluations rank among its top priorities. Accordingly, New York has stated that all past, current, and future contaminated sites will need to be evaluated as to whether there is a potential for exposures related to soil vapor intrusion.