What is radon?

Radon is a naturally occurring, radioactive gas that originates from uranium and radium in soil. Radon can migrate through soil and enter buildings through floors and plumbing. Radon concentrations within buildings can accumulate to levels that may pose a health risk.

Why is radon considered hazardous?

Radon gas decays into radioactive, solid products. These decay products can attach to dust particles, which can then be inhaled. Once inhaled, radon decay products release tissue-damaging radiation. This irradiation of the lungs can lead to lung cancer. Radon is considered to be a leading cause of lung cancer among nonsmokers in the United States. Since radon exposure can produce cancer, the United States Environmental Protection Agency (EPA) has set the indoor radon concentration action level for residential properties at 4 picocuries per liter. The Iowa Department of Health and Human Services limits the radon level for occupational workspaces to 30 picocuries per liter of air.

Testing your home is the only means to assess your radon exposure risk. Testing is easy and affordable and best completed during the cold months when buildings are closed up for heating. Radon test kits can be purchased at many hardware stores or through public health agencies. The purchase price usually includes sample analysis and reports. Likewise, many home inspection businesses can provide testing and mitigation services.

What is environmental radiation?

Environmental radiation exists in our environment from naturally occurring and artificial radiation sources. Often, environmental radiation is termed "background radiation." On average, Iowans receive an annual radiation dose of 300 millirems from natural radiation sources and 60 millirems from artificial radiation sources. Each person's yearly environmental radiation dose will vary depending on their activities and location.

Natural background radiation comes from the following three sources:

Cosmic radiation

The sun and stars send a constant stream of cosmic radiation to Earth, much like a steady drizzle of rain. Differences in elevation, atmospheric conditions, and the Earth's magnetic field can change the amount (or dose) of cosmic radiation we receive.

Terrestrial radiation

The Earth itself is a source of terrestrial radiation. Radioactive materials (uranium, thorium, and radium) exist naturally in soil and rock. Essentially, all air contains radon, which is responsible for most of the dose that Americans receive each year from natural background sources. In addition, water contains small amounts of dissolved uranium and thorium, and all organic matter (both plant and animal) contains radioactive carbon and potassium. Some of these materials are ingested with food and water, while others (such as radon) are inhaled. The dose from terrestrial sources varies in different parts of the world, but locations with higher uranium and thorium soil concentrations generally have higher doses.

Radon gas contributes nearly two-thirds of our natural background radiation exposure.

Internal radiation

All people have internal radiation, mainly from radioactive potassium-40 and carbon-14, inside their bodies from birth and, therefore, are sources of exposure to others. The variation in dose from one person to another is not as significant as that associated with cosmic and terrestrial sources.

In general, the following artificial sources expose the public to radiation (the significant radioactive isotopes are indicated in parentheses):

  • Medical sources (by far, the most significant artificial source)
    • Diagnostic x-rays
    • Nuclear medicine procedures (iodine-131, cesium-137, and others)
  • Consumer products
  • Building and road construction materials
  • Combustible fuels, including gas and coal
  • X-ray security systems
  • Televisions
  • Fluorescent lamp starters
  • Smoke detectors (americium)
  • Luminous watches (tritium)
  • Lantern mantles (thorium)
  • Tobacco (polonium-210)
  • Ophthalmic glass used in eyeglasses
  • Some ceramics

To a lesser degree, the public is also exposed to radiation from the nuclear fuel cycle, beginning with uranium mining and milling through the disposal of used (spent) fuel. In addition, the public receives minimal exposure from the transportation of radioactive materials and fallout from nuclear weapons testing and reactor accidents (such as Chornobyl).