About Radiation

Radiation is a form of energy that is present all around us. There are different types of radiation. All may cause us harm with strong exposures. The dose of radiation that a person receives is measured in units called millisievert or millirem

Some types, called ionizing radiation, may cause harm over time even at low exposures. Ionizing radiation is released by radioactive materials and is measured in units called becquerel or curie.

Find out what to do in a radiation emergency

What is radiation exposure?

Radioactive materials and radiation-producing machines give off a form of energy called ionizing radiation. When a person comes in contact with ionizing radiation, the energy may be absorbed by the body where it may cause harm. For example, when a person has an x-ray or is near radioactive materials, they are exposed to radiation.

How can radiation exposure occur?

People are exposed to small amounts of radiation every day, both from naturally occurring sources—such as elements in the soil or cosmic rays from the sun—and human-made sources. Human-made sources include some radioactive materials (such as iridium-192 in radiographic non-destructive testing or cesium-137 in a portable moisture density gauge), medical sources (such as x-rays and nuclear medicine diagnostic tests and treatments), nuclear power plants, and nuclear weapons testing.

How much radiation are people exposed to?

The amount of radiation from natural or human-made sources that people come in contact with is usually small. Scientists estimate that the average person in the United States receives a dose of about 620 millirem per year. This dose varies depending on where people live, whether they live in a home with radon, or whether they had medical x-rays or nuclear medicine procedures in the past year.

About 50% of human exposure comes from natural sources, including radon, and the remaining 50% comes from human-made sources—mainly medical x-rays and nuclear medicine.

How can I protect myself during a radiation emergency?

Tune to your local Emergency Alert System radio station or TV station for information and instructions from the State of Vermont's health, safety and emergency management departments.

You may be advised to shelter in place, which means to stay in your home or office, or you may be advised to evacuate, depending on the incident. These protective actions are meant to stop or limit contamination and exposure to radiation.

Find out what to do during a radiation emergency

What is radiation exposure and contamination?

When you get an x-ray or are near radioactive materials, you are exposed to radiation, but the dose from this exposure stops when the x-ray is over or you move away from the radioactive materials.

Contamination is radioactive material where it is not wanted. An example is nuclear fallout. If the material settles on the skin or is inhaled or ingested, the person can receive a radiation dose. Radiation dose from contamination stops only when the radioactive materials are removed from your body.

Learn more about contamination versus exposure

Some types of radioactive materials stay in the body and are deposited in different body organs where they remain for months or years. Other types are eliminated from the body more quickly in blood, sweat, urine and feces.

Typical radiation exposure (measured in millirem) from different sources:

  • Radon in indoor air: about 230 millirem per year
  • Air-food-water: about 30 millirem per year
  • Medical procedures: about 300 millirem per year
  • Soils, rocks and cosmic radiation: about 50 millirem per year

The National Council on Radiation Protection and Measurements has captured our average dose in the chart below that shows how much radiation comes from each of the many contributors.

What is Vermont’s Potassium Iodide Distribution Program?

The State of Vermont makes potassium iodide (KI) tablets available free of charge to people who work or reside in the Vermont towns within the Emergency Planning Zone for the Vermont Yankee Nuclear Power Plant. The towns that qualify for free KI are Brattleboro, Dummerston, Guilford, Halifax, Marlboro and Vernon.


Parents and guardians are eligible to receive a free dose for each child in their family. Participation in this program is voluntary. Public schools, nursing homes, hospitals, and some child care centers and private schools in these towns also have KI distribution plans in place.

The Potassium Iodide Program will stop after December 31, 2019, because Vermont Yankee’s spent fuel has been moved into spent fuel casks and most of the fuel’s radioactive iodine has decayed away.

How to request potassium iodide

  • Fill out the request form
  • Either mail the form, or bring it to the Health Department
       Vermont Department of Health
       Potassium Iodide Program
       232 Main Street, Suite 3
       Brattleboro, VT 05301-2881

Learn more about Potassium Iodide

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