EPA Office of Solid Waste and Emergency Response Final Guidance for Assessing and Mitigating the Vapor Intrusion Pathway from Substance Sources to Indoor Air (External Review Draft) by the U.S. Environmental Protection Agency Office of Solid Waste and Emergency Response, April 2013
Vapor intrusion is a potential human exposure pathway ─ a way that people may come into contact with environmental contaminants while performing their day-to-day indoor activities. Figure 2-1 summarizes the vapor intrusion pathway. The exposure route of general interest for vapor intrusion is inhalation of toxic vapors present in indoor air. ….methane and certain other volatile chemicals can also pose explosion hazards when they accumulate in confined spaces.