Radon is a radioactive gas, the 86th element of the periodic table, and a leading indoor health problem in the United States and other countries. Radon occurs naturally in the air, but can build up to harmful concentrations in homes and buildings. Radon remediation is a common and well-understood practice, and generally uses dedicated fans to vent radon-laden air harmlessly to the atmosphere.
What is Radon?
Radon is one of the fundamental elements. It occurs on Earth as a product of the radioactive decay of naturally occurring uranium-238 in the soil. Uranium concentrations in soil are low and always measured in units of parts-per-million. The levels vary regionally, and even neighboring areas can have very different radon risks.
Radon Formation
Radon is formed as a step in the "decay chain" that begins with uranium-238. As the uranium atoms undergo natural decay, they transmute, or change, into other elements with their own decay timelines, like thorium, which then transmutes into several successor elements before becoming radium.
When the radium underneath a home decays into radon, it becomes a gas that moves upwards through the soil. If a foundation or building rests on the soil, the radon atoms will enter it directly through small cracks and imperfections. Once inside the building, the radon gas can accumulate to high concentrations.
Radon Alpha Particles
At each stage in the radioactive chain, the decaying atom emits high-energy particles as it transmutes into the next element. When radon decays, it emits subatomic alpha particles. While these particles don't penetrate the skin, if radon atoms have been inhaled and are in the lungs when decay occurs, the alpha particles can make impact with the cell's nucleus, striking and damaging the DNA there.
Radon and its progeny decay more quickly than their predecessor elements, emitting more high-energy particles in a shorter period of time.
Cellular Damage and Cancer
These high-energy subatomic impacts knock atoms and molecules in the DNA out of position, disrupting the information encoded thereon. If the cell's genetic code is sufficiently damaged by this radioactivity, it can begin multiplying uncontrollably, leading to cancer.
Alpha particles can also form highly reactive charged compounds inside cells and initiate damaging chain reactions that eventually reach cell nuclei and also cause DNA damage.
The National Cancer Institute estimates that radon is the leading cause of lung cancer for non-smokers in the United States.
Radon Testing and Action Levels
Radon mitigation is used when indoor radiation exposure from radon poses a hazard to human health.
The first step in determining whether mitigation is needed is to test the air in your home. Ready-to-use short- and long-term radon test kits can be purchased at many stores as well as online for under $50. They collect air in the home and are then sent to a lab for processing.
The U.S. Environmental Protection Agency uses two scales to indicate unsafe radiation levels, at or above either of which radon remediation is needed. The EPA designates radiation measurements of both 4 picocuries (pCi) per liter, or 150 becquerels (Bq) per cubic meter, as "action levels."
Mitigating Radon Hazards
Radon remediation is a common and often successful way to bring indoor radon down to safer concentrations.
Most mitigation systems use under-floor sump fans to constantly vent radon-laden air from under the foundation to the outdoors. Changes in home ventilation and the sealing of visible foundation cracks may also help lower radon concentrations.
Mitigation systems can be self-installed or placed by a remediation specialist. It is important to monitor and periodically test system performance for proper airflow and adequate radon removal.
