At What Radon Level Should Mitigation Be Considered?

Patient Presentation
A 2-year-old female came to clinic for her health supervision visit. The family had just moved into an old home. During the interview the mother noted that they had had the home checked for lead and for radon. “The radon test said it was normal,” she said. The pertinent physical exam was normal and the diagnosis of a healthy female was made. When discussing the toddler with the resident, the attending said that he didn’t know what was the normal value range for radon. “We don’t do regular screening for radon like we do for lead, so I just don’t know what normal is,” he stated. Later the attending found the numbers and also found more specific information about radon mitigation in his area to have for future encounters.

Radon is a naturally occurring, radioactive gas that is colorless, odorless and tasteless. It is produced from the normal radioactive decay of uranium into radium and then into 222R-Radon. Radon gas escapes from soils and rocks into the air and generally concentrates in enclosed spaces such as buildings, mines and caves. The general ionizing radiation dose received by the general public is caused by radon in large part. In homes and other buildings, soil gas is the most important source of residential radon, but other sources which are less important includes building materials and well water sources.

Indoor radon is the second leading cause of lung cancer after smoking in the US and a major cause of lung cancer deaths worldwide (3-14%). While children could be at higher risk for cancer because of radon exposure, there currently is not conclusive data that supports this. There also is no current strong evidence that radon causes cancers other than lung cancer.

Radon testing is easy and inexpensive to perform. Depending on the building size, location, construction, materials and radon results, more than 1 testing may be needed to determine the overall risk. Repeated radon testing can also be considered if there is increased exposure such as living in a basement apartment. If more than 5% of current buildings in an have elevated radon, new housing and building construction should have preventive radon measures included as they are considered cost effective. Radon mitigation systems can be built into the new construction. For existing dwellings with elevated radion, specific mitigation techniques vary depending on the building construction and materials. Soil suction techniques gather radon from below or at the foundation and vent it away from the structure. There are numerous ventilation techniques that actively or passively increase the ventilation in particular areas or throughout the building to decrease, and hopefully eliminate, the radon concentration. Sealing cracks in foundations/walls is not considered an adequate mitigation technique by itself but can be used as one part of an overall mitigation plan.

Learning Point
Radon concentrates in locations close to the soil and in places with less ventilation. One study of primary schools in Serbia illustrates these points. Radon levels were higher in schools with only one floor, smaller buildings and located geographically in locations known to have higher naturally occurring radon levels. The higher up in the building there was a decrease in the radon levels. The authors point out that an “average” exposure for students really is not possible, as many other factors contribute to the risk including how the school rooms are used, and when are they used (e.g. higher levels on weekends and holidays when building is shut up more, or cold vs. warm seasons)

The United States Environment Protection Agency provides a map of the general radon risk by county. The average level of radon in a US home is 1.3 pCi/L (picoCuries per liter), and about 0.4 pCi/L of radon is normally found in the outside air. Radon mitigation should be considered if the long term levels are 4.0 pCi/L or more. It would be best if there was no radon risk but that is not generally achieveable considering radon’s ubiquitous nature within the world.

Questions for Further Discussion
1. What is the risk of radon in your local area?
2. What other environmental risks are in your local area?

Related Cases

To Learn More
To view pediatric review articles on this topic from the past year check PubMed.

Evidence-based medicine information on this topic can be found at, the National Guideline Clearinghouse and the Cochrane Database of Systematic Reviews.

Information prescriptions for patients can be found at MedlinePlus for these topics: Radon and Indoor Air Pollution.

To view current news articles on this topic check Google News.

To view images related to this topic check Google Images.

To view videos related to this topic check YouTube Videos.

United States Environmental Protection Agency. Radon. Available from the Internet at (cited 12/13/16).

United States Environmental Protection Agency. Consumers Guide to Radon Reduction. Available from the Internet at (rev. 2013, cited 12/13/16).

World Health Organization. WHO Handbook on Indoor Radon. Available from the Internet at (cited 12/13/16).

World Health Organization. Radon. Available from the Internet at (rev. 2009, cited 12/13/16).

Bochicchio F, ZuniC ZS, Carpentieri C, Radon in indoor air of primary schools: a systematic survey to evaluate factors affecting radon concentration levels and their variability. Indoor Air. 2014 Jun;24(3):315-26.

Del Risco Kollerud R, Blaasaas KG, Claussen B. Risk of leukaemia or cancer in the central nervous system among children living in an area with high indoor radon concentrations: results from a cohort study in Norway. Br J Cancer. 2014 Sep 23;111(7):1413-20.

Peckham EC, Scheurer ME, Danysh HE, Lubega J, Langlois PH, Lupo PJ. Residential Radon Exposure and Incidence of Childhood Lymphoma in Texas, 1995-2011. Int J Environ Res Public Health. 2015 Sep 25;12(10):12110-26.

Madureira J, Paciencia I, Rufo J, Moreira A, de Oliveira Fernandes E, Pereira A. Radon in indoor air of primary schools: determinant factors, their variability and effective dose. Environ Geochem Health. 2016 Apr;38(2):523-33.

Donna M. D’Alessandro, MD
Professor of Pediatrics, University of Iowa Children’s Hospital