California Retains Conservative EPA Risk Factors In Vapor Intrusion Guide

California’s newly released final draft supplemental guidance for screening and evaluating vapor intrusion for remediation purposes is maintaining requirements to continue using EPA-backed “attenuation factors” (AFs) for estimating risks, which some industry representatives are criticizing as ignoring years of work by state regulators to develop less-conservative, state-specific factors. “The response to comments after three years of sitting on the whole thing look more like a litany of excuses looking to justify the policy rather than the best available science that...