Radiation is everywhere. It's been part of our environment since the planet was born. Radiation exists in the atmosphere, the ground, the water and even within our own bodies. It's called natural background radiation, and it's perfectly safe.
Radiation affects your body by depositing energy in your tissues, which can cause cell damage. In some cases, this won't cause any effect. In others, the cell can become abnormal and later malignant. It depends on the strength and duration of the exposure. In the rare occurrence of a huge amount of radiation exposure in a short time, death can occur in a matter of days or hours. We call this acute exposure. Chronic exposure, on the other hand, is frequent exposure to low doses of radiation, over a long period. There can be a delay between initial exposure and consequent health effects. To date, the best information we have about health risk and radiation exposure comes from the survivors of the atomic bomb in Japan and people who work with radiation every day or receive radiation as medical treatment.
We measure amounts of radiation exposure in units called millirem (mrem). Higher readings are measured in mSv, which you can multiply by 100 to get mrem. In the United States, people receive an average annual dose of about 360 mrem. More than 80 percent of this dose comes from natural background radiation [source: DOE]. However, outside considerations greatly affect the average dose. Where and how you live affects the amount of radiation exposure you receive. For example, people who live in the Pacific Northwest part of the United States typically only receive about 240 mrem from natural and man-made sources. However, people in the Northeast receive up to 1700 mrem per year, mostly due to radon that is natural to rocks and soil. Is 1700 mrem safe? Take a look at the sidebar to see.
So what do you do if you're exposed? Find out on the next page.