Radon: What Is It and Why Is It Dangerous?

Radon is a naturally occurring, radioactive, odorless, colorless, tasteless gas. It dramatically increases the risk of cancer in those who inhale air contaminated with it for long periods of time.

The second leading cause of lung cancer in the U.S., the gas is responsible for more than 20,000 deaths in the U.S. each year.

Radon is formed by the radioactive decay of uranium deposits in rocks, soil, and water, scattered around the globe, including all fifty states in the U.S. Radioactive particles contain energy, which is released as the particles decay. The rate of radioactive decay is measured in units called picocuries (pCi) in the USA, taking the name from the early pioneer of radioactivity research, Marie Curie. The rest of the world use Becquerel (Bq).

As uranium decays through a long string of reactions, radon gas is formed, escaping to the surface of the earth and dissipating into the atmosphere. The average amount of the gas in outdoor air measures about 0.2 picocuries per liter of air (pCi/L) or 7.4 Becquerel per cubic meter (Bq/m3). The average indoor air level of radon ranges between 1 and 2 pCi per liter or 37 and 74 Bq per cubic meter.

If radon gas is released beneath the foundation of a building, it seeps through porous construction materials, cracks, and openings, into basements, crawlspaces, and walls.

If the structure does not have adequate ventilation, the gas builds to unhealthy levels causing damage to the lungs of those who breathe it in. The U.S. EPA suggests that action is taken to reduce contamination levels once they reach 4 pCi/L (148 Bq/m3) to maintain a safe radon environment.

Once inside the lungs, radioactive decay of atoms continues and particles of alpha radiation are ejected with speed and force. Delicate cell nuclei and DNA in the path of ejected alpha particles can be severely damaged structurally, causing mutations and other malfunctions in reproduction, sometimes resulting in cancer.

There are no immediate symptoms that indicate disease or predict the cumulative effects of exposure. Since lung cancer is monoclonal in nature, meaning that it can originate from damage to just a single cell. The only way to know for sure whether a building is a safe radon environment is to test and monitor the air for contamination.

The U.S. EPA estimates that one in fifteen homes in the U.S. exposes residents to unsafe levels of radon gas.

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