Radon is a chemical element with symbol Rn and atomic number 86. It is a radioactive, colorless, odorless, tasteless noble gas, occurring naturally as a decay product of radium. Its most stable isotope, 222Rn, has a half-life of 3.8 days.
Three reasons Radon stands out
- 1
This element is the second leading cause of lung cancer.
- 2
It seeps naturally from soil and rock into homes, where it can build up to dangerous concentrations in basements.
- 3
It is the heaviest naturally occurring noble gas, produced by the radioactive decay of radium in the ground.
A noble gas that seeps from stone
Radon forms when radium decays in rocks and soil. As a gas it can enter buildings through foundations, where inhaled decay products irradiate lung tissue. It has no smell or color, so testing—not human senses—is the only reliable way to find dangerous indoor accumulation.