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Radon in Schools


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The U.S. Environmental Protection Agency (EPA) and other major national and international scientific organizations have concluded that radon is a human carcinogen and a serious environmental health problem. EPA estimates that radon may cause about 21,000 lung cancer deaths in the U.S. with an estimated 400 deaths in Iowa each year. However, this number could range from 7,000 to 30,000 deaths per year. The U.S. Surgeon General has warned that radon is the second-leading cause of lung cancer deaths. A nationwide survey of radon levels in schools estimates that nearly one in five has at least one schoolroom with a short-term radon level above the action level of 4 pCi/L (picocuries per liter) – the level at which EPA recommends that schools take action to reduce the level. The amount of radon gas in the air is measured in picocuries per liter of air. EPA recommends that schools take action to reduce the level of radon when levels are 4 pCi/L or higher.

Radon Facts

Radon is a naturally occurring radioactive gas that is colorless, odorless, and tasteless. It comes from the natural breakdown or decay of uranium which is found in soil and rock all over the United States. Radon travels through soil and enters buildings through cracks and other holes in the foundation. Eventually, the uranium decays into radioactive particles that can become trapped in your lungs when you breathe. As these particles in turn decay, they release small bursts of radiation. This radiation can damage lung tissue and lead to lung cancer over the course of your lifetime. EPA studies have found that radon concentrations in outdoor air average at 0.4 pCi/L. However, radon and decay products can accumulate to higher concentrations inside a building.

School Construction and Radon

Typically it is easier and less expensive to design and construct a new building with radon-resistant and/or easy-to-mitigate features than to add these features later to existing buildings.  For areas with elevated radon levels, architects and engineers should use a combination of radon prevention construction techniques in new construction of schools.  Three radon prevention techniques for construction of schools and other large buildings in radon-prone areas:

  1. Install an active soil depressurization (ASD) system – creates a low-pressure zone beneath the slab by using a powered fan to create a negative pressure beneath the slab and foundation,
  2. Pressurize the building using the heating, ventilating, and air conditioning (HVAC) system,
  3. Seal major radon entry areas – floor/wall cracks, expansion joints, and around piping systems.

Many schools are constructed on adjoining floor slabs which permit radon gas to enter through construction and expansion joints between slabs. Other features, such as the presence of a basement area, crawl spaces, utility tunnels, subslab HVAC ducts, cracks, or other penetrations in the slab (e.g., around pipes) also provide areas for radon to enter indoor spaces. Depending on the design and operation of heating, ventilation and air conditioning (HVAC) systems, HVAC systems can influence radon levels in schools by:

  • Increasing ventilation (diluting indoor radon concentrations with outdoor air);
  • Decreasing ventilation (allowing radon gas to build up); pressurizing a building (Keeping radon out); and,
  • Depressurizing a building (drawing radon inside).

Radon Testing

Testing is the only way to determine whether or not the radon concentration in a school room is below the action level. Measuring levels of radon gas in schools is relatively easy and an inexpensive process compared to other important building upkeep activities. Each frequently occupied room that is in contact with the ground should be measured because adjacent rooms can have significantly different levels of radon. EPA has published guidance that is available free to schools throughout the country. The basic elements of testing are:

  • Test all frequently used rooms on and below the ground level;
  • Conduct tests in the cooler months of the year; and
  • Follow this school testing strategy:
    • Step 1: Initial testing – take short-term tests.
    • Step 2: Follow-up testing:
      • Take a second short-term test in rooms where the initial level is 4 pCi/L or higher.
      • Take a long-term test in these rooms for a better understanding of the school-year average radon level.
    • Step 3: Take action to reduce levels if the average of the initial and short-term follow-up test is 4 pCi/L or greater or the result of the long-term test is 4 pCi/L or greater.

Current Radon Testing Requirements for Schools

Radon Mitigation Strategies

School buildings are more complex in their construction and operation than most houses. Diagnostic measurements are necessary to develop and implement an appropriate mitigation strategy. Two mitigation strategies are effective in school buildings:

  1. venting radon gas from beneath the building slab (active sub-slab depressurization – ASD), and
  2. pressurizing and ventilating a school building with an HVAC system (HVAC pressurization/ventilation). ASD has been a successfully used strategy in homes and school buildings when initial radon levels are above 20 pCi/L. HVAC pressurization and ventilation has been used successfully to reduce radon levels to below EPA’s action level guideline of 4 pCi/L.

Frequent Questions about Radon

EPA provides answers to frequent questions about radon on this website: Radon FAQs

Radon EPA Publications

Links for additional information about radon

EPA Map of Radon Zones - Iowa

map of Iowa indicating that all of Iowa's 99 counties are at the highest risk for radon


Printed from the Iowa Department of Education website on March 21, 2018 at 11:18pm.