Most states are utilizing multiple lines of evidence in evaluating vapor intrusion. When assessing the vapor intrusion pathway, flux measurements were only used by less than one-third of the respondents, while all other media were used in vapor intrusion analysis at a rate of 80% or higher. The most popular medium to evaluate vapor intrusion is shallow soil gas or subslab gas. The second most frequent media to be evaluated is groundwater, followed by indoor air and deep soil gas. Direct soil analysis was used more than flux measurements at vapor intrusion sites.

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32-38. For which media does your agency evaluate the vapor intrusion pathway?