What Is Radiation?

The EPA says ionizing radiation has so much energy it can knock electrons out of atoms, a process known as ionization, and that because it can affect the atoms in living things, it poses a health risk by damaging tissue and DNA in genes. It says non-ionizing radiation, such as radio waves, visible light and microwaves, has enough energy to move atoms in a molecule around or cause them to vibrate, but not enough to remove electrons from atoms.

The EPA, citing the National Council on Radiation Protection and Measurements, says the average annual radiation dose per person in the United States is 6.2 millisieverts, or 620 millirem, and that another 48 percent of the average American dose comes from medical procedures, a total that does not include the dose from radiation therapy used to treat cancer, which is typically many times larger.

The EPA says exposure to very high levels of radiation, such as being close to an atomic blast, can cause acute health effects such as skin burns and acute radiation syndrome, and long-term effects such as cancer and cardiovascular disease, while exposure to the low levels encountered in the environment does not cause immediate health effects but is a minor contributor to overall cancer risk. The CDC says the guide for radiation safety is ALARA, as low as reasonably achievable, that even small doses should be avoided if practical when they have no medical benefit, and that time, distance and shielding are all strategies that can help you stay safe from radiation.