Vapor intrusion (VI) can create harmful indoor environments. Through VI, dangerous pollutants located underground and out of sight can migrate into homes and work places. Heating and air conditioning use, wind, and weather changes draw subsurface vapors, such as petroleum fumes or solvents, into enclosed spaces. VI criteria are unique. Whether using existing data or newly generated data, trust FTCH to evaluate the relevant and applicable VI criteria and help you navigate regulatory changes to keep your building safe.