Kyle Copeland 

Civil Aerospace Medical Institute 

Federal Aviation Administration 

Oklahoma City, OK 73125 

July 2016 

Final Report 

DOT/FAA/AM-16/5 

Office of Aerospace Medicine 

Washington, DC 20591 

ESRAS: An Enhanced Solar 

Radiation Alert System 
NOTICE 

This document is disseminated under the sponsorship of 

the U.S. Department of Transportation in the interest of 

information exchange. The United States Government 

assumes no liability for the contents thereof. 

___________ 

This publication and all Office of Aerospace Medicine
 

technical reports are available in full-text from the
 

Civil Aerospace Medical Institute’s publications website:
 

http://www.faa.gov/go/oamtechreports
 
Technical Report Documentation Page 

1. Report No. 2. Government Accession No. 3. Recipient's Catalog No. 

DOT/FAA/AM-16/5 

4. Title and Subtitle 5. Report Date 

ESRAS: An Enhanced Solar Radiation Alert System July 2016 

6. Performing Organization Code 

7. Author(s) 8. Performing Organization Report No. 

Copeland, K 

9. Performing Organization Name and Address 10. Work Unit No. (TRAIS) 

FAA Civil Aerospace Medical Institute 11. Contract or Grant No. P.O. Box 25082 

Oklahoma City, OK 73125 12. Sponsoring Agency name and Address 13. Type of Report and Period Covered 

Office of Aerospace Medicine 

Federal Aviation Administration 

800 Independence Ave., S.W. 14. Sponsoring Agency Code Washington, DC 20591 

15. Supplemental Notes 

16. Abstract 

Since 2003, The Federal Aviation Administration has operated a Solar Radiation Alert System to aid the 

aerospace community and interested members of the flying public in their decision making with regards to 

solar ionizing radiation. The first alerts were issued during the solar storms of late October 2003. In the years 

since its initial operation, several improvements have been made to the calculations behind the dose rates 

and the means of communicating the results to the aerospace community and the flyin g public. The basic 

method of satellite data evaluation described in earlier reports remains unchanged, but it has been updated 

and expanded. This report describes the most recent improvements, as well as those planned for inclusion in 

the next few years. The recent improvements include: new atmospheric response functions for protons, 

expansion of calculations to middle and low latitudes, and continuous updating of a global map of the most 

recent calculations. Other improvements planned include: the additio n of solar alpha particle flux to the 

calculations, corrections for geomagnetic disturbance effects on global dose rates, and corrections for 

anisotropy based on available neutron monitor data. 

17. Key Words 18. Distribution Statement 

Radiation, Solar Radiation, Protons, Ionizing Radiation, 

Radiation Protection, Dosimetry, Solar Proton Event, 

Document is available to the public through 

the Internet: 

http://www.faa.gov/go/oamtechreports/ 

Solar Radiation Storm, GOES, ESRAS, SRAS, ArcGIS 19. Security Classif. (of this report) 20. Security Classif. (of this page) 21. No. of Pages 22. Price

Unclassified Unclassified 12 

Form DOT F 1700.7 (8-72) Reproduction of completed page authorized 

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ACKNOWLEDGMENTS
 

For editorial assistance with this report, I thank Michael E. Wayda of the Civil Aerospace Medical Institute, FAA. 

For help with ArcGIS mapping I thank Hobi Haque and Lawrence Paskoff, also of the FAA. Thanks to Marcus Davidson, FAA, for help with Python scripting and SFTP issues. My thanks to the many attendees of Space Weather 

Week for their feedback year after year, leading to improvements. Finally, thank you to all those who have contributed 

and supported this ongoing effort over the years, some of whom have passed on, most notably: Wallace Friedberg, 

Ph. D. (FAA, ret.) and Herbert Sauer, Ph. D. (University Center for Atmospheric Research, Boulder, CO, ret.). 
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Contents 

ESRAS: AN ENHANCED SOLAR RADIATION ALERT SYSTEM

1. INTRODUCTION ...................................................................................................................................................................... 1

2. ENHANCMENTS....................................................................................................................................................................... 1

2.1 Summary of the Previous System ........................................................................................................................................ 1

2.2 Recent Changes....................................................................................................................................................................... 1

3. FUTURE FEATURES ................................................................................................................................................................ 4

4. REFERENCES............................................................................................................................................................................. 4

APPENDIX A................................................................................................................................................................................... 1

APPENDIX B................................................................................................................................................................................... 5
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ESRAS: AN ENHANCED SOLAR RADIATION ALERT SYSTEM

1. INTRODUCTION

During air and space travel, passengers and crew

may be exposed to ionizing radiation at higher dose 

rates than members of the general population. For air 

travelers and for future space tourists that do not go 

into orbit, the principal source of ionizing radiation is 

galactic cosmic radiation (See Appendix A for a glossary of 

radiation related terms). This radiation consists of ions 

of nearly every element in the periodic table. These ions 

travel at speeds approaching that of light. This radiation 

is so highly penetrating that shielding of vehicle occupants and components is impractical with current propulsion technologies. This radiation is also essentially 

isotropic (having the same intensity from all directions) 

and slowly varies in intensity (typically by about a factor 

of two) over the course of a solar cycle (about 11 years). 

Because shielding is impractical and dose rates are relatively low (a few to a few tens of microSieverts per hour 

[μSv/h], depending on altitude, geomagnetic effects, 

and solar activity), radiation protection strategies for 

occupants of these vehicles rely on limiting individual 

cumulative exposures to below recommended limits. 

While galactic cosmic radiation is the natural background radiation for flights, occasionally a disturbance 

in the Sun leads to a large flux of solar protons and alpha particles with sufficient energy to penetrate Earth’s 

magnetic field, enter the atmosphere, and increase ionizing radiation levels at aircraft flight altitudes (geopotential 

altitudes are reported) to levels significantly above galactic cosmic radiation levels. Since 2003, the Aerospace 

Medical Research Division at the Civil Aerospace Medical Institute (CAMI) of the Federal Aviation Administration (FAA) has maintained and continues development of a solar radiation alert system [Copeland et al., 

2005; 2009] to provide information on these events, 

referred to as Solar Proton Events (SPEs), as they occur. 

This report describes the most recent enhancements, as 

well improvements planned for inclusion in the next few 

years. 

2. ENHANCMENTS

2.1 Summary of the Previous System 

Previous versions of the FAA Solar Radiation Alert 

(SRA) system continuously evaluated measurements of 

high-energy protons made by instruments on Geostationary Operational Environmental Satellite (GOES) 

satellites, operated by the National Oceanic and Atmospheric Administration (NOAA). If measurements indicated the likelihood of a substantial elevation of ionizing-radiation levels at aircraft flight altitudes at polar 

latitudes (locations with a vertical cutoff rigidity of ~0 MV), 

alert messages were issued to the public through NOAA's Weather Wire Service (NWWS). The specific criteria for issuance of an SRA was that the estimated effective dose rate induced by solar protons at 70,000 ft 

equaled or exceeded 20 microsieverts per hour (μSv/h)

for each of three consecutive 5-minute periods, equivalent to a level 3 event on the D scale [Meier and Mathiä, 

2014]. Because of the potential for a delay of 3-20 

minutes in communication processes and the three 5-

minute periods, notification of the start of alert conditions may have been 18-35 minutes after the start of the 

first 5-minute period. While alert conditions persisted, 

updates were sent through the NWWS. The alert was 

canceled when the average effective dose rate at 70,000 

ft remained less than 20 μSv/h for six consecutive 5-

minute periods. 

2.2 Recent Changes 

As the previous alert system did, the Enhanced Solar Radiation Alert System (ESRAS) operates continuously to monitor the potential hazard of increased particulate ionizing radiation from the Sun using GOES 

data as the basis for the hazard analysis. With respect to 

sending messages through the NWWS, nothing has 

been changed, but improvements have been made in the 

calculations: The solar proton fluence to effective dose 

conversion coefficients have been recalculated using the 

final release of the Monte Carlo transport code MCNPX 

2.7.0 [ORNL, 2011]; calculations have been expanded 

from polar latitude to include middle and low latitudes, 

while still assuming isotropic incident radiation; and a 

continuously updating global map of the most recent 

calculations is generated. New data sets are available 

using the contact information provided in Appendix B. 

The tables used to convert proton fluence to effective dose at selected altitudes were recalculated using 

MCNPX 2.7.0 as part of the development of CARI-7 

(FAA software used to calculate flight doses from galactic cosmic radiation) [Copeland, 2014]. The new conversion coefficients are based on considerably more trials 

and include secondary heavy and light ion transport that 

was missing in the coefficients calculated using MCNPX 

2.6.0. 

Previously, the system calculated dose rates at 0 

gigavolts (GV) effective vertical cutoff rigidity (i.e., polar 

latitude) locations. The expansion to middle and low 

latitudes is based on global calculations of effective vertical 

cutoff rigidity by Smart and Shea using the 2010 International Geophysical Reference Field [Smart and Shea, 

2012]. These data, for geomagnetically normal conditions (no geomagnetic storm in progress), are shown in 

Figure 1. For each calculated location, these effective 

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vertical cutoff rigidities are used as a pass band filter, vertical cutoff. During a geomagnetic storm the cutoff 

screening out particles with rigidities below the effective rigidities would usually shift towards the equator. 

Figure 1. Vertical magnetic cutoff rigidities in GV for the 2010 epoch calculated by Smart and Shea using the IGRF 

2010 internal reference field [Smart and Shea, 2012]. 

The expansion of Web technologies and the FAA's 

adoption of ArcGIS graphical display software provides 

an opportunity to share the data on a global scale in a 

manner accessible by everyone by using a visual, rather 

than text-based, means of presentation. The new nonzero cutoff data are thus displayed as continuously updating maps of dose rate at points of equal effective vertical cutoff rigidity along lines of constant geographic 

longitude, color coded to the D scale at 70,000 ft (flight 

level 700). Figures 2 and 3, respectively, show what these maps look like during normal conditions (all D700 = 1 

or 0) and during a large solar proton event (D700 = 3 or 

more for some locations). While the specific details may 

change when full mapping capabilities are added to the 

FAA's public servers, these maps show the basic layout 

and what can be done now with ArcGIS Web. 

Clicking on an active (colored) point on the map brings 

up a report of solar dose rates at altitudes from 20,000 

ft. to 70,000 ft. for that location. 

"When Date: 20150918 

UTC 18:25 

From GOES-Primary 

Lat -30.00

Long -60.00

VertCut (GV) 10 

Level 1 

Code green 

Alt Dose rate (microSv/h) 

20000! 0.0000E+00 

30000! 0.0000E+00 

40000! 0.0000E+00 

50000! 0.0000E+00 

60000! 0.0000E+00 

70000! 0.0000E+00 " 

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Figure 1. Solar radiation map for normal conditions. Red dots would indicate D700 = 3 or more, yellow would indicates D700 = 2, while green indicates D700 < 2. 

Figure 2. Solar radiation map mockup for conditions during a large solar proton event. Red dots indicate D700 = 3 or 

more, yellow indicates D700 = 2, and green indicates D700 < 2. 

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3. FUTURE FEATURES Available from the Massey Library collection at RMC, 

from the Canadian National Archives in Ottawa, Cana- The planned future enhancements to calculations in- da, and from the author (kyle.copeland@faa.gov). clude: the addition of solar alpha particle flux to the 

dose calculations, corrections for geomagnetic disturb- Hada, M. and Sutherland, B.M. (2006). Spectrum of 

ance effects on global dose rates, and corrections for complex DNA damages depends on the incidence radiaanisotropy based on available neutron monitor data. tion. Radiat Res, 165, 223-230. 

Other improvements that can be expected in the next 

few years include publishing global maps to the Internet Hall, E.J., and Giaccia, A.J (2006). Radiobiology for the radiat a permanent address and, as the older GOES satel- ologist (6th Ed.). Philadelphia: Lippincott. 

lites are phased out, a revision of the GOES proton 

spectrum evaluation algorithm to match the new International Commission on Radiological Protection 

GOES-N satellite series data, which are planned to be (1991). 1990 recommendations of the International Commission 

different in binning and energy range from previous on Radiological Protection (ICRP Pub. 60). Tarrytown, NY: 

GOES proton flux measurement instruments. The next Elsevier Science. 

generation map will likely be expanded to multiple layers, with each layer presenting the data at a different International Commission on Radiological Protection 

altitude, using color coded polygons, to further ease in- (2007). The 2007 recommendations of the International Comtuitive understanding of the dose rate data being pre- mission on Radiological Protection (ICRP Pub. 103). London: 

sented. Elsevier; 2007. 

4. REFERENCES International Commission on Radiological Protection 

(2009). Adult reference computational phantoms (ICRP Pub. 

Copeland, K., Sauer, H.H., and Friedberg, W (2005). 110). London: Elsevier. 

Solar radiation alert system (Office of Aviation Medicine 

Report DOT/FAA/AM-05/14). Washington, DC: Of- Meier, M.M., and Matthiä, D. (2014). A Space Weather 

fice of Aerospace Medicine. Available at: Index for the Radiation Field at Aviation Altitudes, J. 

www.faa.gov/data_research/research/med_humanfacs/ Space Weather Space Clim. 4, A13. DOI: 10.1051/ 

oamtechreports/2000s/media/200514.pdf Accessed 22 swsc/2014010. Available at: www.swsc-journal.org/ 

Sept. 2015. articles/swsc/pdf/2014/01/swsc140002.pdf. Last accessed 22 Sept. 2015. 

Copeland, K., Sauer, H.H., and Friedberg, W. (2009). 

Solar radiation alert system (revised May 30, 2008) (Office of National Council on Radiation Protection and MeasAviation Medicine Report DOT/FAA/AM-09/6). urements (NCRP) (1993). Limitation of exposure to ionizing 

Washington, DC: Office of Aerospace Medicine. radiation (NCRP Report 116). Bethesda, MD; NCRP. 

Available at: www.faa.gov/data_research/research/ 

med_humanfacs/oamtechreports/2000s/media/200906 Oak Ridge National Laboratory (2011), Computer program Monte Carlo n-particle transport code system for multipar- .pdf Accessed 22 Sept. 2015. 

ticle and high energy applications (MCNPX 2.7.0), RSICC 

Copeland, K.A. (2014). Cosmic ray particle fluences in the code package C740. 

atmosphere resulting from primary cosmic ray heavy ions and their 

Smart, D. F., and Shea, M.A. (2012). World grid of calculat- resulting effects on dose rates to aircraft occupants as calculated 

ed cosmic ray vertical cutoff rigidities from IGRF 2010 (in par- with MCNPX 2.7.0. (A doctoral thesis at the Royal Mili- tial fulfilment of FAA Procurement AAM-610-12-0157). tary College of Canada [RMC], accepted July 2014). See Appendix B for access information. 

 

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APPENDIX A
 

Glossary of radiation related terms 

Absorbed Dose: The amount of energy absorbed by a medium divided by the mass of the medium. It is a macroscopic dose quantity. The medium could be the human body, a particular tissue or organ in the body, or some other 

object such as some part of a solid-state electronic device. The SI unit is the gray (Gy), where 1 Gy = 1 joule per kilogram (J/kg). 

Ambient Dose Equivalent: Ambient dose equivalent is defined by the International Commission on Radiation 

Measurements and Units (ICRU) and the International Commission on Radiological Protection (ICRP) [ICRP, 1997] 

as the dose equivalent measured within a 30-cm diameter sphere of tissue equivalent material irradiated by a plane parallel beam. Doses at various depths, d, along the axis of the sphere opposing the incident radiation beam depth are denoted by H*(d). It is measured in units of joule per kilogram with the special name sievert (Sv). Because instruments 

can be calibrated to measure it, in aviation it is used as a surrogate measure of effective dose. 

D index: A dose rate assessment index first suggested by Meier and Matthia [2014]. The D index ranks dose rate by 

powers of 2, normalized to 5 microsieverts per hour at D = 1, i.e., 

D = log2 (E/5) (A1) 

Dose Equivalent: ICRU and ICRP [ICRP, 1991] define dose equivalent (H) as the product of the absorbed dose and 

the quality factor (Q), i.e., 

H = D . Q (A2) 

The value of Q is specified by the ICRP as relating to the unrestricted linear energy transfer, L ∞, of the radiation depositing the dose. The current recommended relationship is: 

L ∞/ keV. μm-1 Q(L ∞) 

<10 1 

10-100 0.32 L ∞ - 2.2 

>100 300 (L ∞)-1/2 

Dose equivalent is measured in units of joule per kilogram with the special name sievert (Sv). 

Effective Dose: Effective dose, E, was introduced as a radiation protection quantity by the ICRP in their 1990 recommendations [ICRP, 1991]. The U.S. National Council on Radiation Protection and Measurements (NCRP) published a slightly different definition in its Report 116 [NCRP, 1993]. Most recently, the ICRP currently defines effective dose as a weighted average of the sex-averaged organ equivalent doses to several different radiation-sensitive organs and tissues [ICRP, 2007]: 

⎛ ⎞ E = ∑w HT = ∑wT ⎜∑wRD , ⎟ (A3) T T R
 

T T ⎝ R ⎠
 

The tissue weighting factors, wT (Table A1), take into account the sensitivity of the various organs and tissues to radiation induced stochastic effects while the radiation weighting factors, wR (Table A2), account for the relative biological 

effectiveness of each of the various radiations incident on the body. The anthropomorphic phantoms to be used in 

the calculations are now specified and are defined in ICRP Publication 110 [ICRP, 2009]. It is measured in units of 

joule per kilogram with the special name sievert (Sv). Dose limits are often expressed in effective dose. 

Effective Vertical Cutoff Rigidity: There is a region above the minimum vertical cutoff rigidity where not all rigidities 

allow access. The effective vertical cutoff rigidity is a single value used to represent the effect of this region on particle 

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access. It is usually slightly greater than the minimum vertical cutoff rigidity. Ideally, it is chosen such that calculations 

using the entering particle spectrum and treating the effective vertical cutoff rigidity as a sharp cutoff yield the same 

results as the physical measurements of the system, such as neutron monitor count rates, aircrew doses, etc. 

Galactic Cosmic Radiation: Radiation from outside our solar system. 

Geopotential Altitude: Altitude system based on height above mean sea level adjusted for gravity. In a standard atmosphere with an assumed, fixed temperature profile, pressure is constant with respect to geopotential altitude. Altitudes differ from geometric altitude by less than 1 percent below a few hundred thousand feet. 

Gray: The gray (Gy) is the International System (SI) unit of absorbed dose of ionizing radiation. One Gy is 1 joule (J) of 

radiation energy absorbed per kilogram (kg) of matter. 

Heavy ion: Traditionally, an ion in the galactic cosmic ray flux that is an atom of element 3 or higher (i.e., lithium and 

heavier) that has been stripped of all its electrons. It is also referred to as an HZE (high Z [atomic number] and E [energy]) particle. Sometimes the term can include any stripped nucleus with more than one nucleon. Astrophysicists and 

astronomers also call these metals. 

HZE: See heavy ion entry. 

Ionizing Radiation: Radiation that is sufficiently energetic to directly or indirectly eject an orbital electron from an 

atom. 

ICRU Sphere: An ICRU-defined phantom. It consists of a 30-cm diameter tissue-equivalent sphere. 

Isotropic: Equal from all directions. 

Linear Energy Transfer (LET): Linear energy transfer is the average amount of energy per unit track length imparted to a medium by ionizing radiation of a specified energy, when penetrating a short distance. The energy imparted to 

the medium includes energy from any secondary radiation, such as nuclear particles released from a nucleus impacted 

by a high-energy neutron. LET is usually expressed in units of keV•μm-1 (thousand electron volts per micrometer). A 

radiation with an LET <10 keV•μm-1 is generally considered low-LET. Photons, muons, electrons, and positrons are 

almost always low-LET. A radiation with an LET >50 keV•μm-1 is generally considered high-LET. Neutrons, pions, 

and alpha particles are examples of radiations that are most often high-LET. Except near the end of its track, a proton 

is low-LET. However, protons are more damaging than other low-LET radiations (Hada and Sutherland, 2006). Thus, 

when risk estimates are calculated, protons are sometimes grouped with high-LET radiation. 

Metals: See heavy ion entry. 

Organ equivalent dose: The organ equivalent dose (also called equivalent dose), H, to a tissue or organ T from radiation R is defined as: 

H = w D (A4) T ,R R T ,R

where, wR is the radiation weighting factor for radiation R (Table A.1) [ICRP, 1991; 2007], and DT,R is the absorbed 

dose to tissue or organ T from radiation R. The values of wR are based on the relative biological effectiveness (RBE) for stochastic effects. For each type of primary radiation from outside the body (or internal emitter), the radiation weighting 

factor takes into account the effectiveness of the primary radiation and all its secondary radiations. For multiple radiations, HT, the total organ equivalent dose to tissue or organ T is the sum of the organ equivalent doses from each type 

of radiation: 

HT = ∑HT ,R (A5) 

R

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Particle spectrum: The distribution of particle fluence or flux, usually with respect to particle energy, particle energy 

per nucleon, or particle rigidity. 

Primary Radiation: In this context, radiation that reaches the top of Earth's atmosphere (See also secondary radiation). 

Percent Deviation: An indication of the degree of variation of one quantity, "A" relative to another, "B". 

Percent deviation = 100 (A-B)/B (A6) 

Phantom: A target defined for performing calculations of dose in simulated exposures to ionizing radiation. It may be 

simple, like the ICRU sphere (a sphere of solid homogeneous tissue), or it may very complex, such as those defined in 

ICRP Publication 110 (derived from whole-body CT scans) [ICRP, 2009]. 

Rigidity: Momentum per unit charge. Rigidity (R) is used in cosmic ray propagation problems because particles of the 

same rigidity all follow the same path through a magnetic field. 

Relative Biological Effectiveness: Relative biological effectiveness (RBE) is the ratio of absorbed dose of a reference 

radiation (e.g., gamma radiation from the decay of cobalt-60) to absorbed dose of the radiation in question, in producing the same magnitude of the same effect in a particular experimental organism or tissue. The RBE is influenced by 

the biological endpoint and the LET of the radiation. For example, the RBE for killing human cells increases with an 

increase in LET to about 100 keV•μm-1 and then decreases with further increase in LET. At LET 100 keV•μm-1, the 

average separation between ionizing events is close to the diameter of the DNA double helix (a few μm). Therefore, a 

radiation with LET 100 keV•μm-1 can most efficiently produce a double-strand break in a DNA molecule by a single 

LET track [Hall and Giaccia, 2006]. Double-strand breaks in DNA molecules are thought to be the main cause of 

DNA related biological effects, because they are more difficult to properly repair than are single strand breaks. 

Secondary Radiation: Particles or photons produced by the interaction of primary radiation with matter (see also 

primary radiation). 

Sievert: Sievert (Sv) is the SI unit of organ equivalent dose, ambient dose equivalent, and effective dose. It quantifies harm from 

stochastic effects. 

Solar Cosmic Radiation: Ionizing radiation from the Sun. 

Solar Cycle: While the Sun has several cycles, in this context it refers specifically to the approximately 11-year cycle of 

change of polarity of the Sun's magnetic field. This both modulates galactic cosmic radiation and the occurrence of solar 

proton events. 

Solar Proton Event: Event defined by NOAA as 3 or consecutive 5-minute periods with flux of 10 pfu of solar protons with energies at or above 10 MeV. 

Solar Radiation: See solar cosmic radiation. 

Stochastic Effect: Radiation effect for which the chance of incidence, but not the severity, is related to the dose (e.g., 

cancer). 

Vertical Cutoff Rigidity: The rigidity a particle must have to approach a location from the vertical direction. It is often used as an indicator of the effectiveness of the Earth's magnetic field at deflecting energetic ions arriving from 

outer space. 

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Table A.2. Recommended values for radiation weighting factors ( wR).a 

Type and ene rgy of the radiation 	 wR 

Photons, electrons, muons

Protons, charged pions 

Alpha particles, fission fragments, heavy ions 

Neutrons (energy, En) 

En <1 MeV 

En 1 MeV to 50 MeV 

En >50 MeV 

ICRP (2007) 

1 

2 

20 

2.5 + 18.2 x exp[ -(ln(En))2 /6] 

5.0 + 17.0 x exp[ -(ln(2En))2 /6] 

2.5 + 3.25 x exp[ -(ln(0.04En))2 /6] 

 NCRP (1993) 

Photons, electrons, muons 1 

Protons b 2 c 

Alpha particles, fission fragments, heavy ions 20 

Neutrons (energy, En) 

 En <10 keV 5 

 En 10 keV to 100 keV 10 

 En >100 keV to 2 MeV 20 

 En >2 MeV to 20 MeV 10 

 En >20 MeV 5 

 ICRP(1991) 

 1 

5 

20 

5 

10 

20 

10 

5 

 a For radiations not in the table, both ICRP and NCRP recommend using the mean quality factor, rounded up to the nearest whole number. 

 b Except recoil protons, Ep >2 MeV. 

 c If Ep >100 MeV, NCRP suggests wR=1 is more appropriate. 

Table A.1. ICRP [1991; 2007] recommended values for tissue weighting factors (wT). 

Pub. 60 Pub. 103 

Tissue Tissue Weight Factor Tissue Tissue Weight Factor 

Gonads 0.20 Bone marrow (red) 0.12 

Bone marrow (red) 0.12 Colon 0.12 

Colon 0.12 Lung 0.12 

Lung 0.12 Stomach 0.12 

Stomach 0.12 Breast 0.12 

Bladder 0.05 Remainder tissues B 0.12 

Breast 0.05 Gonads 0.08 

Liver 0.05 Bladder 0.04 

Oesophagus 0.05 Oesophagus 0.04 

Thyroid 0.05 Thyroid 0.04 

Skin 0.01 Liver 0.04 

Bone surface 0.01 Bone surface 0.01 

Remainder tissues A 0.05 Skin 0.01 

Brain 0.01 

Salivary glands 0.01 

A Adrenals, brain, upper large intestine small intestine, kidneys, muscle, pancreas, spleen, thymus and uterus. 

B	 Adrenals, extra-thoracic region, gall bladder, heart, kidneys, lymphatic nodes, muscle, oral mucosa, pancreas, 

prostate, small intestine, spleen, thymus and uterus/cervix. 

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APPENDIX B
 

Data Availability 

Due to the large size of the tables, the following data are made available electronically: 

• Atmospheric response tables to convert primary particle fluence to effective dose at altitude for protons and

alpha particles.

• A 1 by 1 degree world grid of effective vertical cutoff rigidities at 20 km.

Please send e-mail requests and inquiries to: 

9-AMC-AAM600-SPECIMENS@faa.gov

And postal requests to: 

Kyle Copeland, Ph.D. 

Protection and Survival Research Laboratory, Numerical Sciences Research Team 

Federal Aviation Administration 

Civil Aerospace Medical Institution, AAM 600 

P.O. Box 25082 

Oklahoma City, OK 73125 

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