Atmospheric Ionizing Radiation and Human Exposure (original) (raw)

Ionizing Radiation in Earth's Atmosphere and in Space Near Earth

The Civil Aerospace Medical Institute of the FAA is charged with identifying health hazards in air travel and in commercial human space travel. This report addresses one of these hazards - ionizing radiation. Ionizing radiation is a subatomic particle of matter or packet of energy (photon) with sufficient energy to eject an orbital electron from an atom. Charged subatomic particles from exploding stars (supernovae) are a constant source of ionizing radiation in the atmosphere and in space. In space another constant source of ionizing radiation is the solar wind from the Sun. The solar wind consists mostly of electrons and protons with energies between 10 and 100 keV. The Sun undergoes an approximately 11-year cycle of rise and decline in activity and during its active phase there is an increased emission of the solar wind and occasional eruptions of high-energy particles (coronal mass ejections). Other sources of ionizing radiation during air travel include radioactive cargo, radioa...

Radiation in the Atmosphere—A Hazard to Aviation Safety?

Atmosphere

Exposure of aircrew to cosmic radiation has been recognized as an occupational health risk for several decades. Based on the recommendations by the International Commission on Radiological Protection (ICRP), many countries and their aviation authorities, respectively have either stipulated legal radiation protection regulations, e.g., in the European Union or issued corresponding advisory circulars, e.g., in the United States of America. Additional sources of ionizing and non-ionizing radiation, e.g., due to weather phenomena have been identified and discussed in the scientific literature in recent years. This article gives an overview of the different generally recognized sources due to weather as well as space weather phenomena that contribute to radiation exposure in the atmosphere and the associated radiation effects that might pose a risk to aviation safety at large, including effects on human health and avionics. Furthermore, potential mitigation measures for several radiation...

Radiation exposure of aircrews due to Space Radiation

HNPS Proceedings

Space radiation mainly consists of trapped particles inside the Earth’s magnetosphere, galactic and solar cosmic rays. Cosmic rays propagating in the interplanetary medium, reach the top of the Earth’s atmosphere and collide with the molecules of the atmospheric layers creating showers of secondary particles that can be recorded by ground-based neutron monitors or muon detectors. Due to these cascades, the radiation environment in various atmospheric altitudes is entirely different than the one experienced on the Earth’s surface. Space radiation is ionizing (trapped particles, galactic and solar cosmic rays) as well as non-ionizing (ultra-violet radiation). It is known that ionizing radiation is very dangerous for all biological systems, causing a variety of acute and chronic effects. The determination of the occupational exposure of aircrews to space radiation is of great importance. DYnamic Atmospheric Shower Tracking Interactive Model Application (DYASTIMA), as well as its exten...

RADIATION SOURCES IN THE ENVIRONMENT

These experiences underlined the special advantages of the method applied.The determination of environmental radioactivity by in situ gamma spectrometry is fast.Detalied information on the quality and quantity of the component contaminants is provided and a dosimetrically relevant value is obtained for environmental dose rate due to the averaging nature of teh measurement.This type of measurement is, however, rather additional than a substitute to the sampling technique, since its estimation for radioactivity concentration in different environmental media are not always accurate enought for further ecological model calculation. KEYWORDS:conversion factor, dose rate, deposited activity, full absorption peak count rate per unit exposure rate, primordial natural radionuclides, inhomogeneity, response to cosmic radiation. 1.CONCENTRATION IN SOIL Having determined the three separate quantities, N0 /Φ is the full absorption peak count rate per unit fluence rate for a plane parallel beam of photons at energy, E, Nf /N0 is the correction factor for the detector response at energy, E, to account for the fact that the fluence from an extended source in the environment will not be normal to the detector face but rather distributed across some range in angles and Φ /A is the fluence rate at energy E, their product yields the desired conversion factor, Nf /A.For radionuclides uniformly distributed with depth in the soil (α /ρ=0), the term A is in units of activity per unit mass.As such, there is no need to determine the soil density. Although the assumption of a uniform profile in the soil for natural emitters is generally safe, unusual situations where there is markedly different soil strat of varying nuclide concentration may produce anomalous results.This situation could arise if landscaping has been performed where topsoil from a different area has been used.Also, evaluations of the 238 U series must be done with the awareness that 222 Rn escapes from the soil and that the important gamma emitting progeny, 214 Pb and 214 Bi, may not be in equilibrium with 226 Ra in the soil.In fact, there may be a measurable contribution to the fluence rate at one meter above the soil from the progeny in the air, particularly under atmospheric inversion conditions. Disequilibrium is also possible for the 232 Th series due to the exhalation of 220 Rn (thoron), although this is less likely to be as severe due to its relatively short half life. Another effect that may interfere with the interpretation of spectrum is that of radon progeny scavenging during precipitation.In this situation the 214 Pb and 214 Bi assume a surface source distribution that can considerably alter flux and dose rate.For this reason (and to keep people and equipment dry!) it is best to avoid measurements during and for about 2 to 3 hours following rain. It is possible to consider a fallout as having a uniform profile if it is deeply distributed or has been mixed through soil cultivation.Depending upon the source gamma energy, plowing to depth of 15 to 30 cm essentially accomplishes this.Although the distribution does not extend to infinity in a situation such as this, in term of the total gamma flux seen above ground, it is effectively infinite in depth.For in situ applications such as this, the concentration that is measured can be considered as representative of the surface soil. 2.DEPOSITION/INVENTORY For radionuclides that are exponentially distributed with depth (α /ρ >0), the term A is in units of activity per unit area.Although the results of analyses of environmental samples ar frequently reported in terms concentration, the fundametal quantity that is of most use for assessing fallout products is the deposition (sometimes reffered to deposition density or inventory).Whereas the deposition remains a constant, the concentration of a fallout product will vary depending upon the depth distribution.To illustrate this point, consider a radionuclide such as 137 Cs that was deposited in an are 30 years ago from atmospheric nuclear weapons testing.Where the surface soil has retained it, a sample down to 5 cm will yield some concentration, x.On an adjancent strip of land that was plowed deeply, the same sampling protocol will

Natural Radioactivity in Human Environment

Journal Human Research in Rehabilitation

Since the radioactivity can not be detected by senses, the most usual reaction to it is fear of unknown. The majority of non-professionals share the common concept of radioactivity as something mysterious and dangerous. The main reason could be insufficient education as well as lack of public information on the properties of ionizing radiation and also on its influence on the environment. The fact is that radioactivity is inevitably present in human surroundings and that the humanity has been living for millennia without cognition and understanding of ionizing radiation effects. Nevertheless, proper usage of ionizing radiation in many fields of human activity could lead the way of prosperity.