March 14, 2011 -- Evacuees in Fukushima grew more fearful Monday of radiation exposure as Japan experienced its second explosion at a nuclear power plant. This morning on "Good Morning America," chief health and medical editor Dr. Richard Besser discussed some potential hazards of radiation.
Here are five facts to help you better understand radiation exposure.
Radiation can be found naturally and nearly everywhere in the environment. Heat, light and microwaves all emit some form of radiation. Uranium, thorium and radium that emit radiation are found naturally in the earth's soil. This type of exposure is generally not considered a health concern.
Our bodies are all exposed to small amounts of radiation. According to the Centers for Disease Control and Prevention, about 80 percent of human exposure comes from natural sources and the remaining 20 percent comes from man-made radiation sources, mainly medical x-rays. Overall, scientists do not find our everyday exposures harmful.
During a nuclear explosion, people are overexposed to high amounts of radiation over a short period of time and may develop acute radiation syndrome (ARS). Within the first few hours of exposure, people with ARS may experience nausea, vomiting, diarrhea, and skin damage. Over time, the radiation can damage a person's bone marrow and cause internal bleeding and other infections. Most people who do not recover from ARS will die within several months of exposure.
Local communities should have a plan in place in case of a radiation emergency. Check with your town to learn more about its emergency preparedness plan and possible evacuation routes.
During a radiation emergency, such as fears of a nuclear plant explosion, you may be advised to create a "shelter in place." This means you should stay inside your home or office, or perhaps another confined area indoors. To keep your shelter in place effective, you should: close and lock all doors and windows; turn off fans, air conditioners, or any units that bring in air from outside; move to an inner room or basement; keep your radio tuned to the emergency response network or local news to find out what else you need to do.