An outdoor air sample that is representative of the air surrounding a home or building.
Biodegradation:
Decomposition of soil gas into other compounds by the action of microorganisms that exist in the soil.
Breathing Zone:
The area from three to five feet above the ground, lower if small children are present. Indoor air samples should be taken from this zone to ensure that they are representative of the air being breathed in the building.
BTEX:
An acronym that stands for Benzene, Toluene, Ethylbenzene, and Xylene. These compounds are major components of gasoline and are commonly used to indicate the presence of gasoline contamination. BTEX readily biodegrades in soil.
Chlorinated Compounds:
Chemicals such as perchloroethylene (PCE) or tetrachloroethene, and trichloroethene (TCE) that are commonly used in dry cleaning and industrial operations. These chemicals can break down into others, which may be of concern for vapor intrusion. They do not readily biodegrade in subsurface soil and may require active remediation to remove.
Cracks:
A fracture, often a narrow opening in the cement floor or foundation of a building that can provide a means for soil vapor to enter a home or building.
Indoor Air Sample:
An air sample taken from within the living or work space of a home or building that is used to determine the concentration of the chemical that may be inhaled.
Preferential Pathway:
A subsurface feature that exists below ground as a fracture, utility line, or pipeline through which soil gas moves more easily than through the natural soil.
Soil Gas Sample:
An air sample taken from the air in the soil pore spaces. Soil gas samples are used to characterize chemical concentrations in the soil.
Sub-Slab Sample:
An air sample collected immediately beneath a home or building with a basement foundation, and/or a slab-on-grade. Sub-slab samples are collected to determine the concentration of chemicals in the soil vapor beneath a home or building because these chemicals may enter the building.
Summa Canister:
An airtight, stainless steel container which is used to collect air samples. Summa canisters are evacuated and used under vacuum to take indoor air, ambient air, or soil air vapor samples.
Vapor Intrusion Mitigation System:
A mechanical device that applies a low amount of suction immediately below the foundation or the occupied space of the building and collects soil vapors which are then vented to the outside.
