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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 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:
- 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,
- Pressurize the building using the heating, ventilating, and air conditioning (HVAC) system,
- 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 EPA Publications
- Radon Measurement in Schools
- Radon Prevention in the Design and Construction of Schools and Other Large Buildings
- Reducing Radon in Schools: A Team Approach