Background radiation is the ionizing radiation present in the environment. Background radiationoriginates from a variety of sources, both natural and artificial.
Cosmic rays and radionuclides. Which is the main depends on where you are.
Source or mode Annual average dose (mSv)
Inhalation (radon gas) 1.26
External terrestrial 0.48
Ingestion 0.29
Cosmic radiation 0.39
Total natural 2.4
http://www.unscear.org/unscear/en/faq.html
Radiation associated with nuclear disintegrations (alpha, beta and gamma), along with x-rays, is ‘ionizing’ radiation, which means that the radiation has sufficient energy to interact with matter, especially the human body, and produce ions. About 80% of the sources that contribute to the ionizing radiation exposure dose on humans originate from natural radioactivity.
The natural sources are part of the terrestrial environment and include the isotopes of the ground of the Earth and the cosmic radiation, which is being emitted by the Sun and other stellar sources in deep space. Detectable amounts occur naturally in soil, rocks, water, air, and vegetation, from which it is inhaled and ingested into the body. In addition to this internal exposure, humans also receive external exposure from radioactive materials that remain outside the body as well as from cosmic radiation. The energy transferred by ionizing radiation to a body, per mass unit, is called the absorbed dose. The probability of affecting human health is directly related to the absorbed dose. The worldwide average natural dose to humans is about 2.4 mSv per year [(UNSCEAR) 2000].
About ~ 0.5 mSv of the natural sources is from building materials
The major natural radionuclides of concern are thorium-232 (232Th) and uranium-238 (238U) and their decay products, as well as potassium-40 (40K). Thorium and uranium primarily undergo alpha and beta decay and are not easily detectable. However, many of their daughter products are strong gamma emitters. Gamma rays are more penetrating than alpha or beta particles and are most often used to characterize the terrestrial component of the natural radiation environment.
The biggest source of natural background radiation is airborne radon, a radioactive gas that emanates from the ground. Radon and its isotopes, parent radionuclides, and decay products all contribute to an average inhaled dose of 1.26 mSv/a (millisievert per year)
Depends what you mean by "natural background". Concerning effective dose on humans, the other answers are completely right.
If you talk about a measurement background, it might be different, depending on the detector. The main contribution, as said, to the dose is inhaled Rn while in gamma detectors, for example, the most prominent background line is often K-40.
I am missing the regional component. I suppose that depending on the geological formation big differences can be observed.
Hi,
i attach at this answer a file about comparison between UNSCEAR data 2000 and UNSCEAR data 2008 about Ionizing Radiation sources in the world (is ana average...be careful).
About the background in specific radionuclides determination (such as gamma, beta, alpha emitters) by gamma, LSC and /or alpha spectrometry, i think is a long and complex topic, the best way, if Dr. Patil Shrikant want it, is do an a specific question about specific measurements.
Best regards
an NBR is needed in your detector to differentiate between artificial or natural background in low level radiation if you are interested in radiation monitoring.
dear sir ,
below in the attachment you can find a full answer about the background radiation sources, which is a part of my lecture , and if you need it you can downed the full text from my page.
The above responses cover the issue well. I remember hugging a large NaI(Tl) detector almost 1000 metres in a salt mine under Lake Erie; I was fascinated by the gamma-ray spectrum from my body, which was dominated by the K-40 line.
The term "background" is not appropriate in many situations. It is generally used to distinguish it from the signal you are interested to. If you are interested to the dose from radiation you receive at home, there is no "background" but "components" of this total dose. Ad regards the UNSCEAR dose values, take into account that this e arte world average values and some of the components, such as indoor radon, can vary of orders of magnitude from place to place.
Dear Dr,
U-235
U-238
Th-232,
K-40 , they the important background source as well as, cosmic rays .
This is chapter about radioactivity.
Cosmic rays vary strongly with geomagnetic latitude and with altitude. Occasional solar events can give increases of a factor 50 (1956) or even 1500 (AD774).
For cosmic radiation contributing to the world population-weighted effective dose, recent study suggests 0.32 mSv with a range between 0.23 and 0.70 mSv (and subject to the solar modulation condition within about 15%), which is slightly smaller than 0.38 mSv with a range between 0.3 and 2 mSv suggested by UNSCEAR 2000 report.
https://www.researchgate.net/publication/308418725_Evaluation_of_World_Population-Weighted_Effective_Dose_due_to_Cosmic_Ray_Exposure
Article Evaluation of World Population-Weighted Effective Dose due t...
The world population-weighted effective dose is 2.4 mSv/year (3 mSv in 10%)
Inhalation exposure (1.26 mSv/year) is mostly due to radon and thoron.
Ingestion exposure (0.29 mSv/year) is mainly due to 40K and uranium and thorium series (e.g., 210Po, 210Pb and 228Ra).
I guess there's an ambiguity about the term "radiation." Is Dr.Patil interested in human dose, or ionization, or particle fluxes? The first two possibilities have been answered extensively.
I would echo Mr. Anabalagan's answer. K-40 is one of the major isotopes in every human body and throughout the environment.
No, the main source is radon-222. the effective dose is about 1.15 mSv per year.
Regarding Cs-137 and Rn-222: Cs-137 is a fission product that largely entered the environment from atmospheric nuclear tests. Because its half-life is roughly 30 years, the level now is significantly lower because such tests were discontinued by the USA and USSR in 1963.
Rn-222, has a half-life of roughly 3.8 days, is continuously regenerated by its deci-chain parents, and is gaseous. Its main problem exists in closed spaces like basements; it can be inhaled by smokers and is considered to be a cause of some lung and throat cancers.
I'll add an interesting fact. The wealthy district of Montclair, New Jersey was built over the earlier site of the Radium Corporation of America. This was not well known until measurements revealed very high levels of radon in the basements of the homes there. I lived in Livingston, NJ, and knew the Montclair area well.
Don't forget that if you fly too often cosmic rays will dominate; e.g. 6 mSv per annum for long haul aircrew! Also you can get this in single flight for 1 in 50 year solar event.
I think the website http://www.unscear.org/unscear/en/faq.html of the United Nations gives lots of detail and also ranges of radiation as it depende where you live, at which altitude and on which underground. All the other answers just add details.
Indoor radon exposure is the main contributor to background radiation in general. But it is necessary to mention that the burden of radiation caused by radon is highly influenced by the geographical area. Those prone-radon areas have much higher contribution of radon as background radiation compared to other areas with low radon exposure. It is important to mention that radon exposure occurs at home and sometimes at work.
The natural sources are primarily cosmic rays (largely muons) that increase with altitude; i.e. the average annual radiation dose at sea level is 300 mrem. Where I live at 2200 m, it is about 500 mrem. Other natural sources are K-40 and U and Th isotopes and daughters, depending on soil and rock. Roughly 15% of the natural radiation dose comes our own bodies; this is largely K-40 with lower levels of other isotopes. There is still a small level of Cs-137 from nuclear weapons tests in nature. In certain enclosed spaces, e.g. basements, there can be unusually high levels of radon.
Much depends on location and environment. I remember hugging a very large NaI(Tl) crystal at almost 1000 m underground in a salt mine and marveling at the beautiful spectrum of K-40 from my body.
As I've noted before, the question involves "radiation,' not radiation dose.
The major natural radionuclides of concern are thorium-232 and uranium-238 and their decay products, as well as potassium-40, some time we found cesium-137 as a man made isotope but with very low concentrations.
Questions should be presented in a clear way in order to obtain useful and appropriate answrers. In this case it is not clear if the author of the question is interested to:
1) the average human exposure to ionizing radiations, and specifically to natural sources of ionizing radiations (and several answers refer to this); in this case the term "background" is inappropriate;
2) the natural sources of the background you have when you do a ionizing radiation measurement.
In both cases, it should be specified the specific place (of exposure or or measurement) the author of the question is interested to, due to the high variations occurring place-by-place in both the cases, as clearly underlined in many answers.
- Badges
- Science topic
- Similar topics
- Methodology
- Laboratory