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Background radiation is from naturally radioactive materials and cosmic radiation from space. [5] People are exposed to this radiation from the environment continuously, with an annual dose of about 3 mSv. [5] Radon gas is a radioactive chemical element that is the largest source of background radiation, about 2mSv per year. [17]
Human internal radiation due to radon, varies with radon levels [8] 2 2 × 10 ^ 0: Acute-Head CT [7] 3 3 × 10 ^ 0: Annual: 0.34: USA average dose from all natural sources [6] 3.66 3.66 × 10 ^ 0: Annual: 0.42: USA average from all sources, including medical diagnostic radiation doses [citation needed] 4 4 × 10 ^ 0: Duration of the pregnancy: 0.6
The various approaches to setting acceptable levels of radiation risk are summarized below: [14] Comparison of radiation doses - includes the amount detected on the trip from Earth to Mars by the RAD on the MSL (2011 - 2013). [15] [16] [17] [18]
Record radiation levels were found in a house where the effective dose due to ambient radiation fields was 131 mSv (13.1 rem) per year, and the internal committed dose from radon was 72 mSv (7.2 rem) per year. [28] This unique case is over 80 times higher than the world average natural human exposure to radiation.
For comparison, radiation levels inside the United States Capitol are 85 mrem/yr (0.85 mSv/yr), close to the regulatory limit, because of the uranium content of the granite structure. [14] The NRC sets the annual total effective dose of full body radiation, or total body radiation (TBR), allowed for radiation workers 5,000 mrem (5 rem). [15] [16]
The term 'biological shield' is used for absorbing material placed around a nuclear reactor, or other source of radiation, to reduce the radiation to a level safe for humans. The shielding materials are concrete and lead shield which is 0.25 mm thick for secondary radiation and 0.5 mm thick for primary radiation [8]
Background radiation level is widely used in radiological health fields as a standard for setting exposure limits. [1] Presumably, a dose of radiation which is equivalent to what a person would receive in a few days of ordinary life will not increase their rate of disease measurably.
A well designed counting system can detect levels of most gamma emitters (>200 keV) at levels far below that which would cause adverse health effects in people. A typical detection limit for radioactive caesium is about 40 Bq. The Annual Limit on Intake (i.e., the amount that would give a person a dose equal to the worker limit that is 20 mSv ...