RADON: an inert gas

Radon is a chemical element in the periodic table that has the symbol Rn and atomic number 86. A radioactive noble gas that is formed by the disintegration of radium, radon is one of the heaviest gases and is considered to be a health hazard. At ordinary temperatures radon is a colorless gas. When cooled below the freezing point, radon exhibits a brilliant phosphorescence which becomes yellow as the temperature is lowered and orange-red at the temperature of liquid air.

Radon gas can accumulate in buildings, and drinking water, and cause lung cancer [1], causing potentially 20,000 deaths in the European Union each year. Radon is probably the most significant contaminant in indoor air quality worldwide.
The main hazard is from inhalation of the element and its decay products which are collected on dust in the air. Recently, radon buildup in homes from the surrounding soil and rocks has become a safety issue and some areas around the world test homes for radon gas.

Radon atoms are fairly short-lived. Over the course of several days a radon atom becomes a lead atom. While it is a radon atom, however, it is a gas. Because radon is a gas, it can seep from the ground into the air in a house. The primary way that radon enters a house is through the foundation (crawl space, basement) by a variety of paths. Radon can be reduced by preventing its entry into the home or by removing it once it has entered the home. The general solution involves active ventilation either in the basement or below the slab of the home.

There have been no reports of short-term effects or symptoms caused by radon exposure. The only reported long-term effect is lung cancer. If you inhale a radon atom, the atom can disintegrate while it is in your lungs. When it disintegrates, it becomes polonium-218, which is a metal. This metal atom can settle in your lungs, and over the next hour or so it will emit a number of alpha particles, beta particles and gamma rays. It eventually turns into lead-210 with a half-life of 22 years, which is fairly stable in this context. But now you have an atom of lead in your system, which causes its own problems. It is the quick, hourlong sequence of alpha, beta and gamma emissions that can lead to the mutations in the lung tissue, which can cause cancer. Smoking enormously increases the risk of lung cancer from radon exposure.