On April 16, EPA issued a revised proposed guidance for assessing and mitigating vapor intrusion risks from chlorinated solvents and petroleum at cleanup sites. The proposed guidance documents revise earlier versions from last year. The current versions eliminate language from the chlorinated solvents guidance for calculating limits to protect against health hazards from short-term exposure. Instead, EPA is working to separately develop a strategy for addressing short term exposure to chlorinated solvent vapors.

The proposed petroleum guidance reduces the separation distance from light non-aqueous phase liquid (LNAPL) contamination to occupied buildings from 30 feet to 15 feet, which likely will significantly reduce the number of sites that must be evaluated for vapor intrusion from petroleum contamination.

EPA will take comment on the proposed guidance documents until May 24.