Radon-220 is a radioactive isotope of the noble gas radon, which is part of the uranium decay series. It has a half-life of about 55.6 seconds, making it a short-lived gas. Radon-220 is produced from the decay of thorium-232 and is primarily found in soil and rock formations. Due to its short half-life, Radon-220 does not accumulate in the environment like its more stable counterpart, Radon-222. However, it can still pose health risks if inhaled, as it can decay into harmful radioactive particles that may contribute to lung cancer over time.