Frequent Questions

How is vapor intrusion into occupational and other non-residential settings to be evaluated for RCRA Environmental Indicator (EI) determinations?

Occupational settings where persons are in a working situation: 
Such settings could include workplaces where workers are handling hazardous chemicals (e.g., manufacturing facilities) similar to or different from those in the subsurface contamination, as well as other workplaces, such as administrative and other office buildings where chemicals are not routinely handled in daily activities. OSHA and EPA have agreed that OSHA generally will take the lead role in addressing occupational exposures. Therefore, EPA does not expect the November 2002 Vapor Intrusion Guidance to be used in such settings (i.e., primarily occupational). Nevertheless, we recommend that such facilities be notified of the potential for this exposure pathway and that they consider any potential exposure that may result. 

Nonresidential settings where persons are in a non-working situation: 
Nonresidential buildings may need to be evaluated where people (typically non-workers) may be exposed to hazardous constituents entering into the air space from the subsurface. This would include, for example, buildings where the general public may be present, e.g., schools, libraries, hospitals, hotels, and stores. In these situations we believe the November 2002 Vapor Intrusion Guidance may be appropriate, although we recommend appropriate adjustments be made for nonresidential exposure durations, the building specific air volumes and air exchange rates, as well as other relevant factors to be considered.

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