What is the average natural background radiation in the us

A number of sources of natural radiation penetrate our bodies through the food we eat, the air we breathe and the water we drink. Potassium is the main source of internal irradiation aside from radon decay found in a variety of everyday foods. The average effective dose from these sources is approximately 0. However, doses can vary greatly. The following figure shows how Canadian cities and the Canadian average dose compare to other parts of the world. Skip to main content Skip to footer. Natural background radiation November Fact sheet — Natural background radiation PDF Quick facts Radiation has always been present and is all around us in many natural forms.

Life has evolved in a world with significant levels of ionizing radiation. Many radioisotopes are naturally occurring, and originated during the formation of the solar system and through the interaction of cosmic rays with molecules in the atmosphere.

Tritium is an example of a radioisotope formed by this interaction. Radioisotopes such as polonium, carbon and potassium naturally occur within the human body. Potassium is present in many common foods including red meats, white potatoes, carrots, bananas, lima beans and Brazil nuts.

The annual average effective dose from natural background radiation is approximately 1. The electromagnetic spectrum Natural radiation sources Background radiation is a constant source of ionizing radiation present in the environment and emitted from a variety of sources. Inhalation Most of the variation in exposure to natural radiation results from inhalation of radioactive gases that are produced by radioactive minerals found in soil and bedrock.

While in other areas, like the Colorado plateau, radiation levels are closer to twice the national average. For reference, we've also included the average exposure rate for flight crews, as an example of the increased exposure that can result from spending extended periods of time at high altitudes, where there is less atmosphere to shield cosmic radiation.

It is also important to note that that level still falls well below the upper limit for occupational exposure set by the International Commission on Radiological Protection, discussed in much more detail here.

Hourly rates that go above these limits temporarily for hours or even days typically do not represent a health risk. We've also included several examples of areas around the world that are inhabited where background radiation levels are significantly higher than the world average. It is not uncommon for beaches to have higher than average levels of radioactivity, depending on the types of sand present.

For example, there is a coastal town in Brazil, Guarapari , with beaches that have extremely high levels of natural radiation. Learn more about radioactive decay. Terrestrial radiation levels vary by location, but areas with higher concentrations of uranium and thorium in surface soils generally have higher dose levels. Traces of radioactive materials can be found in the body, mainly naturally occurring potassium Potassium is found in the food, soil, and water we ingest. Our bodies contain small amounts of radiation because the body metabolizes the non-radioactive and radioactive forms of potassium and other elements in the same way.

A small fraction of background radiation comes from human activities. Trace amounts of radioactive elements have dispersed in the environment from nuclear weapons tests and accidents like the one at the Chernobyl nuclear power plant in Ukraine.

Nuclear reactors emit small amounts of radioactive elements. Radioactive materials used in industry and even in some consumer products are also a source of small amounts of background radiation.

Learn more about radiation and consumer products. All of us are exposed to radiation every day, from natural sources such as minerals in the ground, and man-made sources such as medical x-rays. The pie chart below shows the sources of this average dose. The radioactivity concentrates and remains in the target organ for example, the thyroid for a longer period of time than does the radioactivity that is distributed to the rest of the body.

The radiation exposure for other parts of the body is a function of the amount of radioactivity per pound and the time the radioactivity is present in the tissue. For example, a hyperthyroid problem such as that experienced by former President George Bush is typically treated with a radioactive iodine drink designed to deliver about 10,, millirems of radioactive iodine to the thyroid. It would coincidentally deliver a dose to the rest of the body of about 20, millirems.

A slightly lower dose of radioactivity is used for cancerous tumors. Radiation to kill a cancerous tumor often involves a beam delivering 6,, millirems to the cancerous tissue, but the whole-body equivalent dose is much less, as it was in the thyroid example cited above.

What is a lethal dose from a single instance of radiation? According to studies made after the atomic bomb explosions in at Hiroshima and Nagasaki, half of the people died whose entire bodies were exposed to , millirems of radiation from the atomic bomb. All persons died whose bodies were exposed to , millirems of radiation. This also was the annual occupational limit for adults from World War II through Limit changed in to 5, millirems. It is "as low as reasonably achievable; however, not to exceed 5, millirems.

An embryo or a fetus of a pregnant worker exposed to radiation a new regulation as of Jan. Potassium is an essential dietary element that is present mostly in the muscles. A localized dose delivers 10,, millirems to the thyroid and about 20, millirems to the rest of the body. A radiation dose to kill a cancerous tumor often sends a beam delivering 6,, millirems to the cancerous tissue, but the whole body equivalent dose is much less, as in the thyroid case. The research showed iron supplements are more effective if not be taken with meals.

The study used radioactive calcium 45 to track calcium absorption.