Introduction to Radon & Health Risk
The Fundamentals of Radon & Radioactivity
Radon Occurrence & Behavior
Radon Measurement & Devices
1 of 3

Introduction to Radon

Radon (chemical symbol Rn) is a naturally occurring radioactive gas produced by the decay of uranium and radium and is found in soils, rock, and water throughout the U.S. Unlike some air pollutants, radon is colorless, odorless, and tasteless and therefore cannot be detected by our senses. Radon is a health threat because it can collect in homes sometimes to very high concentrations and can cause lung cancer.

According to the United States Environmental Protection Agency (EPA), the average radon concentration inside of America’s homes is about 1.3 pCi/L, over four times greater than the average concentration of radon in outdoor air (0.4 pCi/L). The EPA estimates that nearly one out of every 15 homes in the U.S. is estimated to have elevated radon levels. Consequently, radon is the largest source of exposure to naturally occurring radiation and causes approximately 21,000 deaths due to lung cancer each year. To combat this risk, the US EPA set 4.0 pCi/L as the Action Level, or level at which citizens are recommended to take corrective measures to reduce radon levels indoors. The 4.0 pCi/L Action Level does not imply that any level below 4.0 pCi/L is considered acceptable and it is recommended that Americans consider fixing their homes for radon levels between 2 pCi/L and 4.0 pCi/L.

4.0 pCi/L Action Level
Level at which US citizens are urged to take action against elevated indoor radon levels.

Many studies have been conducted to determine the health effects of exposure to indoor radon. The most definitive studies concluding that radon causes lung cancer in humans have been conducted by the committee of the National Research Council on the Biological Effects of lonizing Radiation or BEIR. The BEIR committee has published many reports informing the government and general public on the effects of ionizing radiation. The BEIR studies focused on the health effects of radon exposure to Uranium miners and is the definitive research indicating that radon causes lung cancer in humans. More recently, the World Health Organization indicates in its WHO Handbook on Indoor Radon, 2009, that “the vast majority of radon induced lung cancers are thought to occur following exposure to low and moderate radon concentrations”. [Ref. 26] Of particular significance to the field of radon research, the Handbook concludes that pooled residential studies, such as the Iowa Radon Lung Cancer Study (IRLCS) substantiate a direct method for determining risk without the need for data from miner studies.