H.A.R.M.S. Links:
Newsletter
(Spring 2001)
High Altitude Radiation Monitoring Service
HIGH ALTITUDE FLIGHT
Health and Safety News For Aviation Professionals
(Pilots, Flight Attendants, Aviation Management, and Aero-Medical Professionals)© 2001 HIGH ALTITUDE RADIATION MONITORING SERVICE PO BOX 409, ARLINGTON, VERMONT 05250, USA 802-375-2944
New Topics:
- Recent Solar Activity
- Radiation Associated Chromosome Aberrations Reported in Concorde Pilots
- Solar Storms Impact on Aviation
- Lower Overall Radiation Levels
- Welcome to www.healthycrew.org
- Staying Healthy Keeping Fit
- Why Monitor?
- New NIOSH/FAA Publication
Archive Topics:
- ALARA, What is it?
- Measuring a Radiation Dose
- Occupational Exposure
- Radiation Exposure and Family Planning
- Solar Radiation Events
- What Level of Radiation Exposure is Safe
- Space Weather Makes News
- Strategy to Reduce Radiation Exposure
-
When To Monitor Radiation Exposure
- Ordering a Radiation Monitor
Space Weather Makes News
SPACE WEATHER ADVISORY BULLETIN #02- 2 2002 July 23 at 12:00 p.m. MDT (2002 July 23 1800 UTC)
**** ( CORRECTED ) MAJOR SUNSPOT ACTITVITY ****
A major sunspot region has rotated onto the visible face of the sun. This region, designated as Region 39 by NOAA Space Environment Center forecasters, is believed to have been the source of three large coronal mass ejections on the far side of the sun beginning on July 16. This region will rotate across the visible side of the sun over the next two weeks and is expected to produce more solar activity.
Since appearing on the visible side yesterday (July 22) this region has already produced a major flare at 6:35 pm Mountain Daylight Time (MDT) on July 22 (0035, July 23 UTC). Radio blackouts reached category R3 (Strong) on the NOAA space weather scales. In response to the major flare, a geomagnetic storm is possible and is expected to begin between 8:00 pm MDT on July 23 and 8 am MDT on July 24 (0200 - 1400, July 24 UTC). The geomagnetic storm may reach category G2 (moderate) levels on the NOAA space weather scales.
Category R3 radio blackouts result in widespread HF radio communication outages on the dayside of the Earth and can also degrade low frequency navigation signals. Category G2 geomagnetic storms can lead to minor problems with electrical power systems, spacecraft operations, communications systems, and some navigational systems. Aurora Borealis / Australis (northern / southern lights) may be seen down into the mid latitudes (New York, Madison, Boise, Vladivostok, Rome, Tasmania, Wellington - NZ, Puerto Montt - Chile)
Data used to provide space weather services are contributed by NOAA,
USAF, NASA, NSF, USGS, the International Space Environment Services
and other observatories, universities, and institutions. For more
information, including email services, see SEC's Space Weather
Advisories Web site
NOAA Space Weather Scales
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Radiation Associated Chromosome Aberrations Reported in
Concorde Pilots
Concord pilots whose annual dose of ionizing radiation is estimated to have ranged from 11 to 37 mSv (1100 to 3700 mRem) are reported to have an eight-fold increase in one type of chromosomal aberration. The scientific journal, Mutation Research, describes a study of the chromosomes of a type of blood cells called lymphocytes in 18 Concord pilots and 10 controls. The supersonic crew members studied were found to have significant increases in dicentric chromosomes and chromosomes with micronuclei. Chromosomal changes were attributed by the author to high energy radiation exposure in supersonic aircraft [Heimers A, Mutat Res 2000 May 8;467(2):169-76].
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The solar cycle is at its peak with frequent reports of increases in activity. Coronal mass ejections (CME) with a trajectory toward Earth can effect our environment. Earlier this year two radiation storms, one "strong" and one "severe," were reported by the National Oceanic and Atmospheric Administration (NOAA) Space Environmental Center (SEC). On July 14 at 1614UT, the SEC reported the onset of a strong-S3 radiation storm. This was followed on November 8 at 2350UT by a severe-S4 storm. Based on the NOAA scale, radiation storms ranging from S3 to S5 have the potential for biological effect on crew and passengers flying in high altitude aircraft.
Strong-S3 radio blackouts resulting from solar activity were also reported on June 6th, June 7th, and on November 23rd. Radio blackouts can effect both high and low frequency radio communication, including navigational signals. NOAA scale for strong-S3 radio blackouts state that HF radio experiences wide areas of blackout with loss of radio contact for about an hour on the sunlit side of Earth, while LF navigation signals are reported to degrade for approximately one hour.
NOAA uses its five-point scale to categorize the significance of storms that may have an impact on the navigation, spacecraft and aviation. "The scales describe the environmental disturbances for three event types: geomagnetic storms, solar radiation storms, and radio blackouts. The scales have numbered levels, analogous to hurricanes, tornadoes, and earthquakes that convey severity. They list possible effects at each level. The scales also show how often such events happen, and give a measure of the intensity of the physical causes." Interesting and informative, find the full scale at http://www.sec.noaa.gov/NOAAscales/
Solar events are a normal part of the active phase of the solar cycle. The current cycle, 23, is expected to peak in activity in early 2002. Events, like those reported above, can be expected to occur periodically during the peak of solar activity.
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Lower Overall Radiation Levels
While the solar max does result in more solar storms, it also provides a generally lower level of background radiation due to the stronger than normal solar wind. The high levels of solar wind during the periods of increased solar activity help to deflect cosmic radiation that normally reaches our planet. Overall radiation levels are thus lower during the solar max.
Real-time NOAA forecasts and current solar information, can be reached conveniently from homepage links at http://www.healthycrew.org/
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Welcome to www.healthycrew.org
We have a new web address, new features and links. From our homepage find a hotlink to NOAA bulletins. This will automatically post the most recent warning from NOAA with access to all bulletins issued over the last six months. For real-time NOAA forecasts and data use the "Todays Solar Activity Report and Forecast" link to NOAA. The page that opens is colorful, easy to read and easy to understand. Weekly solar activity forecasts can be reached at "Space Weather Outlook." To reach us, try the new "Contact Us" hotlink that offers a pop-up email screen on most computers.
More aviation health and safety oriented features will be added to the site in the near future. We would like your comments and ideas to improve the site.
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Reports abound in recent medical and scientific journals relating to the importance of diet and exercise in preventing chronic and debilitating illnesses. The risk of cardiovascular disease was reported to be halved in women who consumed high levels (10.2 servings/day) of fruits and vegetables versus those consuming very low amounts (2.6 servings/day)[1]. Vitamin E consumption has been reported to reduce the risk of prostate cancer[2]. Exercise and regular consumption of soy protein are reported to be epidemiologically associated with reduced risk of breast cancer and with a reduction in cardiovascular disease risk factors[3]. A component of olive oil is reported to reduce development of a number of cancers in animal studies [4]. These and many other articles point to health benefits of moderate exercise and a diet rich in fruits, vegetables, whole grains with regular consumption of olive oil and cold water fish such as salmon, mackerel and sardines. Lifestyle choices can make a difference.
- S Liu, et al., Am J Clin Nutr 2000 Oct;72(4):922-8].
- KJ Helzlsouer et al., J Natl Cancer Inst 2000 Dec 20;92(24):2018-2023
- A McTiernan, Medscape Womens Health. 2000 Sep-Oct;5(5):E1.; A Vincent, Mayo Clin Proc 2000 Nov;75(11):1174-84].
- TJ Smith, Expert Opin Investig Drugs 2000 Aug;9(8):1841-8]
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The objective of monitoring is to help informed individuals who are exposed to ionizing radiation to manage their long term exposure and therefore to manage the risks involved. Workers exposed to radiation are taught to endeavor to keep exposure within or below the ALARA standard (As Low As Reasonably Achievable). The recommended ALARA annual administrative limits for occupationally exposed workers in the United States is 200-500 mRem .
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The journal Health Physics, November 2000 published "The NIOSH/FAA Working Women's Health Study: Evaluation of the Cosmic-radiation." The article reports that for the approximately 148,000 flight deck and cabin crew member in the United States, exposure to ionizing radiation result in doses that vary from 0.2 to 5.0 mSv (20 to 500 mRem) per year, while for the average occupationally exposed adult radiation worker in the US, the average dose is 1.1 mSv (110mRem). The article reports that the "International Commission on Radiological Protection has recommended that aircrew exposures to natural radiation in-flight be treated as occupational exposures." The authors point to monitoring and regulation of occupationally exposed workers as important difference in the way that the two groups are treated with respect to their radiation exposure [Waters, M et al., Health Phys 2000 Nov;79(5):553-9].
Please feel free to send inquires about this information or about being monitored for radiation exposure to :
Arlington, VT 05250
or email your comments to
radcount@sover.net
High Altitude Flight,
is a publication of
High Altitude Radiation Monitoring Service,
And of the CMC Foundation
Editor Mardi Crane
© High Altitude Radiation Monitoring Service
PO Box 409,
Arlington, VT 05250.
Email: radcount@sover.net
Phone: 802-379-1807
Permission is granted to reproduce and distribute this document under the express condition that the entire document be replicated and that there be no change to the text and no deletions and no additions without the express written consent of the editor.
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Questions From Customers
We frequently receive letters asking about monitoring, radiation and health related issues. We hope that the following sheds light. Please send any questions for future editions.
Q: Why is radiation monitoring important
in family
planning?
A: Flying can expose reproductive cells and the unborn
to ionizing
radiation. Ionizing radiation can cause genetic defects. In most cases,
the levels of
radiation on board an aircraft translate to a low level of risk to the
unborn child.
However, by monitoring and knowing the
amount of radiation to which
you (both men and
women) are exposed in your
regular flight schedule, it is possible
to have an informed
discussion
with your health care professional about your occupation
and family
planning
.
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Q:
"I have heard on the news about recent solar storms.
Are increases in solar activity
important to flight crew?"
A: The sun is
progressing toward the solar max
which, according to the National Oceanic and Atmospheric
Administration (NOAA), is
expected to peak in the year 2002. With an increase in solar
activity comes an increase
in solar flares. Astronauts are at much greater risk than crew
of commercial aircraft.
However some aircraft are exposed to increased levels of
radiation during solar storms.
According to NOAA,
"Intense solar flares release
very-high-energy particles that can
be as injurious to humans as the low-energy radiation
from nuclear blasts. Earth's
atmosphere and magnetosphere allow adequate protection for
us on the ground, but
astronauts in space are subject to potentially lethal dosages of
radiation. The penetration
of high-energy particles into living cells, measured as
radiation dose, leads to
chromosome damage and, potentially, cancer. Large doses can be
fatal immediately. Solar
protons with energies greater than 30 MeV are particularly
hazardous. In October 1989,
the Sun produced enough energetic particles that an
astronaut on the Moon, wearing only
a space suit and caught out in the brunt of the
storm, would probably have died.
(Astronauts who had time to gain safety in a shelter
beneath moon soil would have absorbed
only slight amounts of radiation.)
Solar
proton events can also produce elevated
radiation aboard supersonic aircraft fly ing at
high altitudes over the polar caps. To
minimize this risk, routine forecasts and alerts
are sent through the FAA so that a
flight in potential danger can alter its course and
reduce altitude to minimize
radiation exposure."
For more detailed information on solar
activity and space weather
see the source of this quote at :
A Primer on the Space Environment
Our Star, the Sun
Increases in solar
activity do not necessarily equate to an
increase in aviation related exposure to
ionizing radiation.
During the solar maximum,
the intensity of the solar wind increases
deflecting some galactic radiation away from
the solar system. This means
that while
the Earth may experience an increase in solar
radiation over this
period, the amounts
of galactic radiation may drop.
In practical terms, during the height of the last
solar cycle, we saw some
relatively
high and other relatively low radiation monitor
readings depending on when a crew member
flew, and how active the sun was during flight
times. During the solar minimum we saw
greater consistency and somewhat higher average
readings. We expect these trends to
continue.
It is important that those who are
regularly exposed to radiation not be
complacent about wearing their monitors or become
complacent about knowing the levels of
radiation to which they are exposed. The most
powerful solar flare in recorded history
occurred during a period of low solar activity.
The primary strategy to reduce radiation exposure on board
an
aircraft
during a solar event is to reduce altitude. It is therefore important for pilots
and
aviation management to pay attention to solar activity during any period of increased
activity. By requesting an
appropriate flight plan, exposure of crew and passengers to
excess ionizing radiation
can be minimized.
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Q: How do HARMS radiation dosimeters differ from those worn by x-ray technicians? Why do crew members need a different type of radiation dosimeter?
A: The HARMS badges are solid state nuclear tracking devices with three components. They are specifically designed to monitor the various types of radiation expected at high altitudes including x-ray, gamma, and beta as well as neutron radiation. Generally an x-ray technician's badge is designed to monitor only x-rays and gamma ray radiation.
The radiation to which crew members are exposed has a significant component of neutron radiation. HARMS badges monitor low and intermediate energy neutron radiation which is significant above 30,000 feet. Most scientists consider this range of neutron radiation to be the most dangerous form of ionizing radiation.
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Q: I have worn a badge for a year. Why should I continue using one?
A: Monitoring radiation exposure is a lifetime part of occupational exposure to radiation. All occupationally exposed workers are urged, if not in most cases, required, to wear radiation monitors. Records are kept on a lifetime basis. Crew members generally do receive in excess of the maximum levels recommended for the general public and do in fact also, receive more radiation than many other radiation workers.
Other considerations are changes in the solar cycle and intermittent solar flares. Some crew members are also exposed to radiation from cargo (generally pharmaceuticals) that are carried on board the aircraft. The only way you can know your level of exposure is if you wear your badge!
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Q: I wear my badge but don't know what level of radiation is considered safe.
A: Safe is a relative term. There is consensus that any level of radiation exposure bears some risk. However the level varies with the type of risk, fatal cancer, genetic mutation or fetal damage, and with the amount of radiation receive d and the duration of exposure.
Most data on human radiation exposure has come from studies of survivors of the bombing of Japan during W.W.II. Most of this exposure was of relatively short duration and at high levels.
Crew members on the other hand are exposed to low levels of radiation over the duration of their careers. When statisticians assess the risk to crews the levels stated are based on theory. To date there is insufficient data about crew health problems to provide hard data.
One approach is to consider the limits set by the Nuclear Regulatory Commission (NRC) for radiation workers and the general public.
The NRC has set the annual limit of radiation exposure for the general public at 100 mRem. The limit set for radiation workers is 2 Rem. However radiation workers are required to wear monitors, are educated in the increased risks associated with radiation exposure and are required to keep their exposure as low as reasonably achievable. It is ultimately your responsibility to know your level of exposure and keep it as low as possible.
Below are some of the levels set by
various governmental and regulatory
bodies.
NRC rec. annual limit of radiation
exposure for the general public
--100 mRem
NCRP
rec. annual limit of radiation
exposure for the general
public --500 mRem
ICRP rec.
limit of exposure for pregnant
woman for term of
pregnancy - 200 mRem
ICRP rec.
annual limit of occupational
exposure (5 year average)
- 2 Rem (20mSv)
ALARA annual
admin. limits for occupationally
exposed workers -
200-500 mRem
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Q: What does the term ALARA mean?
A: ALARA (an acronym for "as low as reasonably achievable") means making every reasonable effort to maintain exposure to radiation as far below dose limits as is practical consistent with the purpose for which the licensed activity is undertaken, taking into account the state of technology, the economics or improvement in relation to the state of technology, the economics of improvements in relation to benefits to the public health and safety, and other societal and socioeconomic considerations, and in relation to utilization of nuclear energy and licensed material in the public interest.(US Nuclear Regulatory Commission NUREG-1446) ALARA recommendations specifically refer to occupational exposure where the source of the radiation is licensed and managed .
Aviation related
radiation exposure is primarily from unregulated
sources. However the
amount and effects
of the radiation is comparable
to other occupational exposures.
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Your questions and comments would be appreciated. Send your email to radcount@sover.net
© 2001 HIGH ALTITUDE RADIATION MONITORING SERVICE