Vapor Intrusion (“VI”) concerns indoor air quality resulting from the entry into a building of hazardous materials through the foundation or floor. VI results from environmental contamination, in particular, the volatilization of volatile organic compounds (VOCs) found below the surface. VOC vapors can rise through the soil and can pass into a building interior through cracks in the foundation. These vapors can remain in interior air, especially in basements, causing a risk of exposure to the building’s occupants. NJDEP’s Vapor Intrusion Guidance (“VI Guidance”) and the draft Immediate Environmental Concern Guidance (“IEC Guidance”) define the duties of responsible party’s for remediation when VI condition is discovered, and set forth strict timelines for addressing suspected VI conditions.