Rn-222

Decay product of uranium thorium or radium. Always present with gamma-emitting decay products. The spectrum is almost identical to that of Radium-226 or natural uranium.

Radon-222 (Rn-222) is a radioactive isotope of radon with a half-life of approximately 3.8 days. It is part of the uranium-238 decay series, formed as a decay product of radium-226. Rn-222 undergoes alpha decay to produce polonium-218, emitting alpha particles during the process. While Rn-222 itself does not emit significant gamma radiation, its decay products (such as lead-214 and bismuth-214) emit gamma rays at characteristic energies, making radon and its progeny detectable using gamma spectrometry. These gamma emissions are widely used in monitoring radon levels in the environment.

Historically, radon was used in radon therapy, where patients inhaled radon gas in controlled environments, though this practice has largely been discontinued due to health risks. Modern applications primarily focus on its role as a tracer in geological and environmental studies, such as tracking air and groundwater movement.

Rn-222 occurs naturally as part of the uranium-238 decay chain. It is found in soil, rocks, and groundwater in areas with high uranium or radium content. It can accumulate in enclosed spaces like basements and buildings, where it is a significant contributor to natural background radiation. High levels of radon in homes and workplaces are considered a health hazard due to its radioactive decay products, which can attach to dust particles and be inhaled. Monitoring and mitigation measures are often implemented in regions with elevated radon levels to minimize health risks.