The American Society for Testing and Materials (ASTM) provides guidance on how to address the problem of vapors spreading in lower levels of building. There is evidence that chemical vapor in subsurface soil can penetrate building foundations at levels that raise health concerns for the occupants, creating liability issues for landlords, lenders, tenants, employers, and others. A vapor encroachment condition (VEC), is defined by the ASTM as the presence or likely presence of volatile organic compound (VOC) vapors in the subsurface of the property caused by the release of vapors from contaminated soil or groundwater either on or near the site. The process by which a VEC is determined is called a vapor encroachment screening (VES). ASTM E2600-10, Standard Guide for Vapor Encroachment Screening on Property Involved in Real Estate Transactions provides guidance and defines a two-tiered approach to assessing a potential VEC.
