What is Normal Background Radiation?

What is Normal Background Radiation?

Background Radiation on Earth

Normal Background Radiation comes from one of two sources.  One type of is radiation that is produced naturally by decaying Atoms that are all around us in our environment.  An example of this would Alpha particles that are produced by the element Radium.  Radium is found quite commonly in the ground and in rocks such as Granite.  It decomposes naturally into Radon Gas and when it does it also produces a particle called an Alpha particle.  Alpha particles are part of Normal background radiation.  Beta particles (electrons) and Gamma rays also existing in our environment and can be measured by special instruments called Geiger Counters.

Ionizing radiation is radiation that can cause other atoms to change state and can induce them to become other types of atoms and can release Alpha or Beta radiation in the process.

What are the Sources of Natural Background Radiation?

One of the most common sources of radiation that effects humans comes from Radon Gas.  Radon gas is formed by the decomposition of the element radon. Radon is found in the soil and various rocks in the earth.  Radon gas is the source of over 50% of the human exposure to ionizing radiation on our Earth.  Other radiation sources are: X-Rays, Gamma Rays, Cosmic Rays, Beta Rays, and Alpha particles.


What Types of Radiation Exist in our Surroundings?

Radiation At Altitude

Background radiation types on earth can be Alpha, Beta, Gamma, X-Rays and Cosmic Rays.  All inhabitants of our planet are exposed to various forms of these types of radiation throughout their lives.  Much of this radiation is naturally occurring.  Some is man-made. Examples this type of radiation are X-Rays used for medical purposes and Atomic Radiation produced as the result of military weapons tests, nuclear power plants, both past and present.

Pilots and flight attendants,  and frequent flyers can receive quite a bit of Cosmic Radiation on airplane flights.  Jumbo jets normally fly quite high above the earth, upwards of 40,000 feet (about 8 miles).  Cosmic radiation at these levels can be up to fifty (50) times the values measured at sea level.

How is Exposure to Radiation Measured?

Exposure to radiation can be measured over the long term by devices called film badges.  When radiation sources penetrate the film on the badges, it exposes the film, and the degree to which the film is exposed is a measure of the incident radiation over time.  Radiation badges are typically worn by workers who are commonly exposed to ionizing radiation such as X-Ray technicians, or medical personnel who work with radiation measurement instruments in laboratories.  Other workers exposed might fall into the category of defense workers or workers in nuclear power plants.

Film badges can be used to measure radiation exposures over long periods of time, such as a week or month.  Film badges as the name implies contain a photographic film emulsion that changes form when it is exposed to radiation. Film badges are used only once, a

Seeing Radiation is Believing

nd may be read by special equipment after longer exposures such a a day, week or month, depending upon the situation. Film badges are usually attached to a persons clothing (like an ID badge).  As another precaution workers also use Geiger Detectors, which are electronic instruments that measure human doses of radiation as it happens.  These meters will let you know of any dangerous levels of ionizing radiation in your immediate area.

Many portable electronic radiation meters are available and can determine incident radiation levels by means of a detector (Geiger Meuller tube) that is sometimes provided as a “wand” device.  As this wand is brought closer and closer to the radiation source, a meter value shown on the body of the instrument will increase.  The user of the device will also hear the device make “clicks” .  The more Clicks heard per minute , the higher  the radiation dose being measured.

How much Natural Radiation Exposure do We Receive in  One Year?

The average person receives about 300 millirems of radiation every year from normal background radiation.  This background radiation consists mostly of  that emanating from  Radon Gas and Cosmic Rays.  A person living at higher altitudes, i.e. a place like Denver Colorado, will be exposed to  about 400 millirems per year on average.

What are the Radiation Limits for Workers in Nuclear Power Plants ?

Nuclear Plant Workers Protection

 Workers in nuclear facilities and weapons manufacturing faculties are limited to annual exposure limit of 5000 millirems or 5 Rems per year. This limit is set by the Nuclear Regulatory Commission.  It works out to about 10 times the rate for  non-worker exposure recommended limits!  This radiation limit is also imposed upon the military as well.

 Some Common Foods Emit Radiation

Certain foods contain various forms of radiation.  This occurs because Vegetables and Fruits and Grains all are grown in the soil.  Radiation occurs naturally in the soil and as a consequence the food also contains some radiation.  Bananas and Kale both are slightly radioactive.  Common salt, or Sodium Chloride (NaCl) s not very radioactive, but a salt substitute which contains Potassium Chloride (KCL)  is, and fixed amounts of it can be used to roughly calibrate Radiation measurement devices.


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