This glossary explains common radon testing and mitigation terms in plain language. For concise machine-readable access, see the Markdown glossary.
Radon
A naturally occurring radioactive gas produced by the decay of uranium in soil, rock, and water. Radon is invisible, odorless, and tasteless, so testing is the only way to know a building’s level.
pCi/L
Picocuries per liter, the unit commonly used to report radon concentration in air in the United States. Learn more in our guide to radon levels and pCi/L.
EPA action level
The U.S. EPA recommends fixing a home when the radon result is 4.0 pCi/L or higher and advises considering action between 2.0 and 4.0 pCi/L.
Short-term radon test
A test that typically lasts from 2 to 90 days. Many real-estate and diagnostic tests use a shorter closed-house measurement period. See short-term versus long-term testing.
Continuous radon monitor
An electronic instrument that records radon readings over time and can help identify unusual test conditions or hourly changes.
Active soil depressurization
A mitigation method that uses a continuously operating fan and sealed piping to draw radon-containing soil gas from beneath a building and exhaust it safely outdoors.
Sub-slab depressurization
A type of active soil depressurization in which suction is created beneath a concrete slab. See our detailed sub-slab depressurization guide.
Sub-membrane depressurization
A mitigation method for crawl spaces that uses a sealed membrane over exposed soil with suction beneath the membrane.
Suction point
The location where mitigation piping connects to the space beneath a slab or membrane so a fan can draw out soil gas.
Pressure field extension
The reach of negative pressure beneath a slab from a suction point. Diagnostic testing helps determine whether the proposed system can influence the required foundation area.
Manometer
A small pressure indicator installed on a mitigation system. It shows whether the fan is creating suction; it does not measure the radon level. See how to read a radon manometer.
Radon fan
A continuously rated fan designed to move soil gas through mitigation piping. Fan selection depends on foundation conditions and diagnostic results.
Follow-up radon test
A radon measurement performed after mitigation to measure the resulting concentration. Air Sense recommends arranging this test separately and confirming the provider, timing, and price in the written estimate; it is not automatically included with installation.
Closed-house conditions
Test conditions that limit outside-air exchange so a short-term result is meaningful. Exterior doors and windows stay closed except for normal entry and exit, subject to the applicable protocol.
Service area
A geographic area where a company performs work. A service area does not by itself represent a staffed physical office.
Primary references
- U.S. EPA radon program
- U.S. EPA Consumer’s Guide to Radon Reduction
- Illinois radon program
- Missouri Department of Health and Senior Services radon guidance
These definitions are general information, not property-specific, medical, legal, regulatory, or contractual advice. Have a term you want explained? Contact Air Sense Environmental.