<?xml version="1.0" encoding="utf-8"?><mads xmlns="http://www.loc.gov/mads/" xmlns:mods="http://www.loc.gov/mods/v3" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.loc.gov/mads/
mads.xsd"><authority><topic authority="http://AATesaurus.cultura.gencat.cat/aat/getty_en">radon</topic></authority><related type="other"><topic>radium</topic></related><related type="broader"><topic>organic material</topic></related><related type="broader"><topic>elements</topic></related><variant type="other"><topic>Rn</topic></variant> <note xml:lang="en"><![CDATA[ Radioactive chemical element having symbol Rn and atomic number 86. It is a colorless, odorless, tasteless inert gas. Radon is formed during the natural decay of radium. It is produced in rock and soil  and migrates to the surface, sometimes entering buildings through basement walls, resulting in low level exposure. Radon’s health risk is associated with the products of radon decay and not with the gas itself.  ]]></note></mads>