What is vapor intrusion?
Vapor intrusion is when vapors from contaminated soil or groundwater move up through the ground and into a building's indoor air.
In more detail
The usual sources are gasoline from leaking tanks and solvents like PCE from dry cleaners and TCE from degreasing. Solvent vapors can travel a long way and enter through cracks, drains and utility lines.
The 2021 update to the Phase I standard made clear that vapor migration is part of a Phase I. A separate standard, ASTM E2600, covers vapor encroachment screening.
Fixes range from sealing cracks to sub-slab depressurization systems, which work like radon systems.
What it means when you buy
Vapor can make a building's indoor air a problem even when the contamination is next door. It matters most for apartments, schools and day cares, where limits are strictest.
How the pre-screen handles it
The pre-screen looks for the sources that cause vapor intrusion (dry cleaners, stations, solvent users) on the site and nearby, ranked by distance.
Pre-screen a property before you spend on a Phase I
A desk review of one address: past uses from historical photos and maps, federal and state environmental records, and flood risk, ready usually within the hour. $100 for one report, or $100/month for 3.