Vapor intrusion and population exposures to toxic or hazardous materials are commonly regulated by local health authorities and permitting agencies.  The transport of vapors in various subsurface soil and into the vicinity of permeable structures provides a pathway of exposure to toxic and hazardous materials.  RTP staff have conducted surveys to identify vapor intrusion and worked with engineering groups to provide solutions that mitigate exposures to sensitive receptors.  Since the problems are usually localized and specific to individual projects, a detailed discussion of the issues and the potential solutions or mitigative measures would then be recommended.  You should contact your local RTP office to obtain information on the solutions RTP can provide.