Radon

Radon is a radioactive noble gas with atomic number 86, produced naturally in uranium and thorium decay chains. Its colorless, odorless gas can accumulate indoors and expose people to ionizing radiation.

Radium-226: A radioactive isotope of radium that decays into radon-222. It is the immediate parent of the radon isotope that commonly enters buildings.
Radon test: A measurement of radon concentration in indoor air or water. Testing determines whether a building's indoor concentration warrants action.
Radon and lung cancer: The established association between inhaled radon decay products and increased lung-cancer risk. This health effect is the principal reason indoor radon is measured and reduced.
Noble gas: An element in group 18 of the periodic table, generally characterized by low chemical reactivity. Radon's chemical inertness and gaseous state shape how it moves through buildings.
Radon-222: The radon isotope in the uranium-238 decay chain, with a half-life of about 3.8 days. Its lifetime allows it to migrate from soil into indoor spaces.
Radon mitigation: Methods for reducing radon concentrations in buildings, commonly by venting soil gas outdoors. Active soil depressurization can prevent radon from entering occupied rooms.
Ionizing radiation: Radiation energetic enough to remove electrons from atoms or molecules. Radon's emitted particles are a source of ionizing radiation.
Uranium-238: A naturally occurring radioactive isotope of uranium and the starting nuclide of a long decay series. Its decay chain produces radium-226 and ultimately radon-222.
Radioactive decay: The spontaneous transformation of an unstable atomic nucleus, often emitting particles or electromagnetic radiation. Radon is continually replenished as uranium and thorium decay.
Radon detector: A device that measures radon concentration or records exposure over time. Detector choice affects whether a result represents a short-term reading or long-term average.

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