Radon-222:
• is a gas;
• is odorless;
• is tasteless;
• is invisible;
• mixes with air;
• is chemically inert (or non-reactive);
• is found everywhere;
• decays by alpha-particle emission; and
• has a half-life of 3.8 days.
Radon Decay Products, or RDPs:
• are solids, called daughters or progeny;
• are chemically active;
• are electrically charged;
• can attach to air particles and cling to surfaces;
• have a ratio of progeny-to-radon gas ranging from 0.3 to 0.7 ER (equilibrium ratio),
averaging 0.5 ER;
• are short-lived (from 0.2 milliseconds to 26.8 minutes);
• include Polonium-218, 214 and 210, which are alpha-particle emitters, and
these alpha-particle emissions can cause physical cellular damage, such as lung cancer.
Risk Assessment Facts
• The EPA’s indoor radon program promotes voluntary public actions to reduce the risks from indoor radon. The EPA and the U.S. Surgeon General recommend that people perform a simple home test using kits which are now widely available in stores. If high levels of radon are confirmed, it is recommended that those high levels be mitigated or reduced using straightforward techniques.
• The EPA recently completed an updated assessment of their estimates of lung cancer risks from indoor radon, based on the NAS’s 1999 report on radon titled “The Biological Effects of Ionizing Radiation (BEIR) VI.” This report is the most comprehensive review of scientific data gathered on radon, and builds on and updates their previous findings. The NAS concluded that homeowners should still test and, if necessary, mitigate their exposure to elevated radon levels in their homes.
• Radon is a naturally occurring radioactive gas that is colorless, odorless and tasteless. It’s naturally produced from the radioactive decay of uranium that’s present in soil, rock and groundwater. It emits ionizing radiation during its radioactive decay, changing into several radioactive isotopes known as radon decay products or RDPs.
• Radon gets into the indoor air primarily from soil under building structures. Radon is a known human lung carcinogen and is the largest source of radiation exposure and risk to the general public. Most inhaled radon is rapidly exhaled, but the inhaled decay products readily deposit in the lung tissue where they irradiate sensitive cells in the airways, increasing the risk of lung cancer.
• The NAS BEIR VI Report confirmed the EPA’s long-held position that radon is the second leading cause of lung cancer, and a serious public health problem. The NAS estimates that radon causes about 20,000 lung cancer deaths each year. The report found that even very small exposures to radon can result in lung cancer. They concluded that no evidence exists that shows a threshold of exposure below which radon levels are harmless. The report also found that many smokers exposed to radon face a substantially greater risk of getting lung cancer compared to those who have never smoked. This is because of the synergistic relationship between radon and cigarette smoking.
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