It is well known that ionizing radiation affects our health in many ways and can cause both acute and delayed symptoms such as cancer. However, despite the fact that crewmembers and frequent fliers are exposed to large amounts of radiation on long-haul flights, they have been left in the dark. The US airline industry has ignored the topic for quite some time despite the fact that the International Commission on Radiological Protection classified flight crews as “radiation workers” over 20 years ago (ICRP, 1991) and the FAA agreed that, “air carrier aircrews are occupationally exposed to ionizing radiation” in 1994 (Barish, 2009). These statements justify an exposure limit up to 50 times more than the general public, and while flight crews are estimated to receive one of the highest average doses of any occupationally exposed group in the U.S. (Goldhagen, 1998) including workers at nuclear power plants (Barish, 2001), there are no regulations in place protecting them.
In addition to radiation, crewmembers and passengers are exposed to many other toxins on planes, including flame retardant chemicals, pesticides, and pathogens. Last year, through the implementation of section 829 of the FAA Modernization and Reform Act of 2012, OSHA now enforces the standards pertaining to blood-borne pathogens, hazard communications, and hearing conservation of crewmembers. The subject of radiation however is still governed by the FAA, which in its latest flight crew training Advisory Circular suggests outdated reading materials and links (FAA, 2006). As a crewmember myself, my career of flying mainly long-haul international routes, along with recent discoveries of my health including a high amount of oxidative stress and an inflamed mucosal barrier, has brought this subject close to home and has resulted in the need to learn more about the amount we are exposed to and the detrimental effects it can have on us. I find it unacceptable that crews and passengers are neither educated nor protected from high exposure doses.
Since 2000, airlines operating in the countries of the European Union are required to limit aircrew member’s exposure to cosmic radiation (CAA, 2013). In the U.S., the Nuclear Regulatory Commission’s Code of Federal Regulations require that individuals exposed to radiation receive adequate training to protect themselves and state that these individuals have the right to know how much radiation they have been exposed to (NRC, 2013). The FAA on the other hand only recommends that airlines educate their employees about the risks involved. Since it is not a required action, airlines do not feel the need to inform them. I barely remember receiving one notice in my 25-year career explaining the effects that radiation could have when flying while pregnant. The concluding remarks stated something to the effect that it would be impossible to determine that a disease resulted from radiation exposure and that is important to keep the risks associated with flying in perspective with other risks that are related to chronic diseases. Other than that I have heard nothing. When questioning other flight attendants and pilots about this, I received similar answers. Most are aware of cosmic radiation but not the extent of it and many feel that there is nothing we can do.
Now, more than ever is awareness imperative for several reasons:
The majority of flight attendants and pilots fly until they retire at around 65, resulting in a greater cumulative effect of radiation.
Cross-polar traffic, where radiation levels are the highest, is continuously increasing. In 2011, there were 10,993 one-way crossings (Meehan, 2012).
The sun is nearing the maximum point of its 11-year cycle with solar activity expecting to peak now in 2013. This could result in huge increases in radiation during flights.
Everyone is exposed to ionizing "background" radiation
Energy emitted from a source is generally referred to as radiation. Ionizing radiation has enough energy to remove tightly bound electrons from an atom, causing it to become charged or ionized. It affects health when it results in changes in the cells of the human body by breaking the chemical bonds in molecules. This type of radiation can occur in waves, such as gamma radiation and x-rays that penetrate deeply into tissue, or as particles, such as alpha particles, beta particles, and neutrons.
When determining health effects of radiation, its dose is measured in “sieverts” (replaces the “rem”), or millisieverts (mSv). This measures the “effective dose”, which is a more accurate representation when exposure is limited to one or several body part(s). As an example, a typical chest x-ray involves about 0.1 mSv of radiation exposure, however since it is limited to the chest area, the “effective” dose is only about 0.02 or 0.03 mSv because only the lungs and breasts are exposed to the radiation (Blue, 2000; European Commission, 2000; FDA, 2002; Roguin & Nair, 2007; Shulman, 2008; FDA, 2009). Exposure to cosmic radiation on the other hand affects the whole body, so the
“effective” dose is equivalent to the exposure amount (Blue, 2000).
Cosmic radiation is a naturally ionizing form of radiation that consists of two parts: 1) a permanent component consisting of highly charged particles ejected from the galaxy, or galactic cosmic rays (GCR) and 2) sporadic particles, or solar energetic particles (SEP), that are associated with eruptions on the sun and which varies in intensity according to the sun’s 11-year cycle. The two barriers that protect Earth (the planets magnetic field and the Earth’s atmosphere) decrease the amount of cosmic radiation that reaches the ground, however people will always be exposed to low levels of this as well as other naturally occurring sources of ionizing radiation including radon gas and radioactive elements found in the air, water, rocks, and minerals. Combined, this naturally occurring “background radiation” exposes people in the U.S. to an average effective radiation dose of about 3 millisieverts (mSv) per year. Man-made sources, including diagnostic x-rays and nuclear medicine add an additional 3 mSv per year (Bushberg, 2009). The total can of course vary from person to person depending on their location (higher altitude cities such as Denver have more cosmic radiation) and their medical imaging history.
The National Council on Radiation Protection and Measurement (NCRP), and the International Commission on Radiological Protection (ICRP) offer recommendations for the maximum permissible dose (MPD) of radiation that people should be exposed to. These in turn are usually adopted by government regulatory agencies including the FAA, EPA, and NRC. Both the NCRP and the ICRP agree that the “general public” should not be exposed to more than 1 mSv (equivalent to an effective dose of about 50 chest x-rays) above the average background and medical radiation per year. In its’ Report No. 116, the NCRP states that the effective dose limit is 1 mSv for members of the public “who are exposed continuously or frequently”, however on an “infrequent” basis (not likely to occur often in an individual’s lifetime), the annual effective dose may go up to 5 mSv (2004). The ICRP recommendation is based on the assumption that there is no safe level of exposure, that even the smallest exposure has some probability of causing a stochastic, or long-term effect, such as cancer, and that doses rising above 1 mSv per year will justify protective actions for members of the public (Butler & Cool, 2010).
And then there are those who are occupationally exposed to radiation. The ICRP recommended limit for an occupationally exposed person is a 5-year average of 20 mSv per year with no more than 50 mSv in a single year and the NCRP recommends 50 mSv per year with a maximum permissible dose of 10 mSv times the person’s age (Friedberg & Copeland, 2011). The FAA follows the recommendation of the ICRP. If they had followed the recommendation of the NCRP, a commission chartered by the U.S. congress in 1964, crewmembers maximum permissible annual dose would be less since it is quite common that crewmembers have long careers. As an example, a flight attendant with a 40-year career who retires at age 65 would have had an average annual permissible dose of about 16 mSv (10 x 65 = 650, 650/40years = 16.25 mSv/year) Recommendations for pregnant crewmembers are much less with a dose limit of about 1 mSv for the remainder of the pregnancy or 0.5 mSv in any month (Friedberg & Copeland, 2011). With regards to frequent flying passengers or other travelers, there are no legal limits since this is considered a “voluntary” activity (HPS, 2011).
I was curious to find out why the recommended annual dose limit for crewmembers was set so much higher than the general public. I understand that the nature of the job comes with some risks, however 20 to 50 times the limit of other US citizens? After all, we are made up of the same types of cells. Perhaps they think we are super-heroes and can withstand these levels much better?
According to the NCRP, one of the goals of radiation protection is “to prevent the occurrence of clinically-significant radiation-induced deterministic effects by adhering to dose limits that are below the apparent threshold levels (2012).” Deterministic effects are usually based on acute exposures and are mostly the result of death or malformation of cells. Apparently the ICRP selected an occupational dose limit that “falls just short of unacceptable” before detrimental effects may occur (Butler & Cool, 2010).
The NCRP and ICRP have two other fundamental principles for limiting the doses received by people: justification and optimization. Justification requires that any decision that alters the radiation exposure situation should result in sufficient individual or societal benefit to justify the risks involved. Optimization is based on maintaining all exposure levels “as low as reasonably achievable” (also known as the practice of ALARA). These features are based on the linear, non-threshold (LNT) hypothesis, which assumes that any radiation exposure, no matter how small, carries with it a level of risk that is proportional to the level of exposure. So since there is no safe level and increases in exposure result in incremental increases in stochastic (or long-term low-level exposure) risks until a threshold level is reached that has been known to cause deterministic (acute) radiation symptoms, exposure should be justified and kept as low as reasonably achievable.
According to a senior Health Physics Advisor with the NRC, optimization, or the ALARA practice, is more important than setting dose limits (Sherbini, 2000). The Health Physics Society also states that this philosophy results in
occupational doses that are much lower than the allowable limits and that the average annual effective dose for all occupational workers in the U.S. is less than 5 mSv (Chabot, 2012).
Crews and passengers can be exposed to additional ionizing radiation from several sources including:
The radiation dose received from galactic cosmic rays is affected by four main factors: time spent flying, altitude, latitude, and solar activity. Since radiation is cumulative, the more you fly, the more radiation you are exposed to. In addition, exposure is more intense at higher altitudes as well as higher latitudes. This is because the thinning of the atmosphere at higher altitudes provides less protection, and electrically charged radiation particles are drawn toward the Earth’s north and south magnetic poles. A normal cruising altitude of about 39,000 feet brings the total radiation levels to about 64 times greater than at sea level (Science Daily, 2005), and the exposure rate is about four times as much at 70 degrees north or south latitude than 25 degrees (Blue, 2000). So long-haul flights near the polar region are exposed to a lot more radiation than those flying at mid-latitudes. The final factor is solar activity. Depending on whether the sun is at a solar minimum or maximum (which varies throughout an 11-year cycle), the amount of cosmic radiation can change. At the solar minimum there is less of a shield due to few sun spots so galactic radiation can double. On the other hand, when the sun is at the solar maximum with many sun spots, this may decrease the amount of galactic radiation that gets through.
The FAA has developed a program called CARI that can either be downloaded or used directly from the Web site (jag.cami.jccbi.gov/cariprofile.asp). It calculates the effective dose of cosmic radiation received by those flying between two airports in the world, however the program does not take into account the increased radiation caused by solar flares. I utilized this program to determine radiation exposure on long-haul flights flying at an altitude of 38,000 feet during 05/2013.
The radiation exposure for a flight from Chicago to London was estimated to be 0.055 mSv. To put this in perspective:
Also, according to the CARI program, a one-way trip from Chicago to Shanghai is estimated to expose individuals to 0.091 mSv, which is the equivalent of about four and a half chest x-rays each direction. Crews or frequent fliers are exposed to more than the annual recommended amount for the general public after six round trips. Crews flying three trips a month or about 1000 hours per year may also reach an annual exposure amount of almost 7 mSv. A flight from Los Angeles to London is estimated at 0.071 mSv, and New York to London is estimated at 0.04 mSv.
Passengers and crews on a flight from New York to Hong Kong are exposed to about 0.1 mSv (or the effective dose of five chest x-rays each way). Five roundtrips could exceed the maximum dosage guidelines for the general public (Crampton, 2001).
Reports on pilot exposure to radiation agree that there is a high-exposed group of pilots who may exceed 7 mSv per year (Graweski et al., 2011).
Coast-to-coast flying expose people to less cosmic radiation since they operate at lower altitudes. A round-trip flight from San Francisco to New York is the equivalent of about two and a half chest x-rays, or 0.05 mSv. Twenty round-trips reach the limit for the general population (Drucker, 2002).
Although cosmic galactic radiation may be down slightly during solar maximums, there is the possibility for solar storms, which may result in large amounts of radiation from the sun. The storms are a result of an explosive release of energy from the sun in the form of solar flares and coronal mass ejections. Solar particle events (SEP) are intense flows of radiation from the sun made up of protons and charged particles that are associated with these eruptions. They are rated on a scale from S1 (minor) to S5 (extreme) according to the amount of very energetic and fast solar particles that move through a given space in the atmosphere. Flights that rely exclusively on radio communications, such as those routed through the poles, may be re-routed during a an SEP event since it can disturb the regions through which high frequency radio communication travel (Fox, 2012). Passengers and crews may be exposed to a radiation risk during storms that are rated S2 (moderate) or higher (NOAA, 2005). These solar flares can increase the radiation exposure level by a factor of 10 or 20 and can last anywhere from a couple of hours to a couple of days. Each possible solar particle event may add an additional 1 mSv per flight to the cumulative galactic cosmic radiation effective dose (Beck et al., 2009) and could add up to a lifetime neutron dose of 46 mSv (Graweski et al., 2011). Anyone that happens to be working on one of those flights might be exposed to the equivalent of 50 chest x-rays or more. If a storm is rated as an S-5 on the center’s scale, which is the most extreme, exposure can be equivalent to 100 chest x-rays (Crampton, 2001).
Flares are based on a classification system that groups them according to their strength. The smallest one is classified as A, followed by B, C, M and X. Each letter represents a 10-fold increase in energy output so an X flare is ten times greater than an M flare and 100 times greater than a C. In addition, there is a finer scale from 1 to 9 for the A through M flares. The X-class flares can go higher than this. Although it is the last letter, there are flares that are more than 10 times stronger than an X1. During 2003, during the last solar maximum, the most powerful flare cut out the sensors measuring it at X28 (Fox, 2011).
The sun is now once again nearing the maximum point of its current cycle. 2013 was expected to be a tumultuous year (Wrenn, 2012; Mosher, 2011) and that seems to be holding true. So far there have been quite a few flares in the last few months and toward the end of the year, there could be several a day (Palmer, 2013). The cycle, called Solar Cycle 24, started in 2008 and is expected to run until 2019-2020 (Malik, 2013). The last peak was in 2000-2001 but included solar storms in Oct-Nov 2003, during which the levels of solar radiation increased by 1000 times in a few hours (AFA-CWA, 2010), as well as solar proton events. One event measured by NASA resulted in a solar cosmic radiation dose of 0.35 mSv per hour, or the equivalent dose of over 17 chest x-rays an hour (Copeland et al., 2008).
August 9, 2011 – The strongest flare so far at X 6.9
The first X-class flare of the current cycle was on February 15, 2011 (X 2.2) Since then, there have been another 15 X-class flares (NASA, 2013) These include:
March 7, 2012 – The second strongest flare so far at X 5.4. On flights from Chicago to Stockholm, the radiation exposure was 0.251 mSv (about 13 chest x-rays) and from Chicago to Beijing it was estimated to be 0.365 mSv (about 18 chest x-rays) (Meehan & Kunches, 2012).
May 12-13, 2013 – Three solar flares occurred within 24 hours. They measured X 1.7, X 2.8, and X 3.2. All of them were associated with coronal mass ejections (Fox, 2013).
In addition to cosmic radiation, we might be exposed to radiation from thunderstorms that produce electrical breakdowns called “dark lightning”. This phenomenon can emit large amounts of gamma-rays, called Terrestrial Gamma-Ray Flashes, or TGFs, in the process. If flying near the tops of these electrified storms, the radiation doses are equivalent to 1 mSv, or a year worth of recommended radiation for the general public. And near the middle of the storms, the radiation dose could be ten times larger, roughly equal to a full-body CT scan (Florida Institute of Technology, 2013).
A Nuclear Regulatory Commission study estimated that the average annual radiation dose to crewmembers from radioactive cargo is about 0.3 mSv (FAA, n.d.), which is equivalent to an additional 15 chest x-rays. With regards to backscatter scans at airports, a single scan expose people to about 0.1 microsieverts or about 0.0001 mSv. Approximately 200 scans are equivalent to one chest x-ray and 10,000 are equivalent to the recommended yearly dose of radiation for the general public (Shauer, 2011). While the dose per scan is very low, every little bit of radiation adds to the total cumulative amount that crewmembers and frequent fliers receive. It is interesting to note that x-ray technology is not an authorized method of screening at EU airports. This was implemented to protect the health and safety of their citizens (European Commission, 2011).
Ionizing radiation is a well-known carcinogen that produces highly reactive free radicals (by stripping away electrons from atoms) that can damage the DNA, lipids, and proteins, and lead to unnatural chemical reactions in cells. Once damage occurs at the cellular level, and the body is unable to repair or replace the damaged tissue, an uncontrolled growth of cancer cells or mutations in the DNA may occur. Radiation to just about any organ can have both acute and chronic adverse effects, however they differ in their radiosensitivity. According to the Merck Manual for Health Care Professionals (Bushberg, 2009), the top six most critically affected tissues include:
There are many studies done on the adverse health effects from acute radiation poisoning. The effects of doses less than 100 mSv spread out over long periods have been difficult to track, however recent scientific studies are unveiling detrimental effects at these lower doses as well. This is largely due to increasing incidences with increasing times after exposure. There is now available data from atomic bomb survivors with 40-50 year follow-ups using a newly implemented dosimetry system, from studies of people exposed to radiation for medical reasons, and studies of nuclear workers exposed at low doses and dose rates (NAS, 2005).
In 2006, the FAA canceled their 1994 Circular and replaced it with a new one that states, ‘The likelihood of developing cancer because of occupational exposure to galactic radiation is a small addition to health risks experienced by the general population. Currently, it is not possible to establish that an abnormality or disease in a particular individual resulted from exposure to galactic cosmic radiation at the doses likely to be received while flying.” (FAA, 2006). After finding an extensive amount of information that indicate otherwise, this statement is not very convincing.
The National Academies of Science released a 700-page report on the risks from ionizing radiation in 2005, in which it was confirmed that there is no safe level of exposure and that even very small amounts can cause cancer. In the study, low doses were defined as those ranging from nearly zero to about 100 mSv. According to the report, the risk of getting cancer from radiation is increased by about a third from current government risk figures. The numbers estimate that 1 in 100 members of the public would get cancer if exposed to 1 mSv per year for a 70 year life-time (NIRS, 2005). Crewmembers can be exposed to more than 7 times this amount per year from galactic radiation alone throughout their career (estimated using the FAA computer program CARI-6).
A recent 15-country study of cancer risk among radiation workers in the nuclear industry confirmed a “significant association” between radiation dose and all-cause mortality (Cardis et al., 2007). Keep in mind that crewmembers are exposed to more radiation than U.S. nuclear plant workers. Also, cancer studies from 2002 to 2007 provide evidence that “cancer risk factors for occupational exposures are not lower than for atomic bomb survivors.” This is based on low-dose-rate, moderate-dose exposure to the order of 100 mSv. (Jacob et al., 2009). Crews can easily be exposed to this from galactic radiation alone flying 15 years of regular-scheduled polar flights (7 mSv times 15years). According to the American College of Radiology, a linear increase of cancer risk at doses in excess of 50 mSv has been directly observed by epidemiological research (Picano et. al., 2007). Crews can be exposed to this after only seven or eight years. And according to the NCRP, there is a consistent body of evidence for the carcinogenicity of ionizing radiation in humans. Absorbed doses of less than 200 mSv have been associated with leukemia, and cancer of the thyroid, breast, and lung (NCRP, 2011). Crews can easily be exposed to this from galactic radiation alone flying 30 years of regular-scheduled polar flights.
Recently, more data have surfaced that reveal other adverse health effects from chronic low doses of radiation. In a 2011 report, the ICRP described the detrimental effects of low-dose radiation on the development of cataracts, circulatory disease, and immune dysfunction. As a result of a study on radiation-induced cataract (Jacobs et al., 2011), the ICRP revised the occupational annual dose limit that was considered safe for the eyes from 150 mSv to 20 mSv. In addition, they also suggested lowering the threshold dose for circulatory disease after evidence of higher incidence of injury than expected at lower doses and described in detail the effects of radiation on the lymphatic tissues and the bone marrow, which are an important part of the immune system (ICRP, 2011). In one study, significant immunological effects were observed in those who were exposed to low-dose radiation (Chang et. al., 1999).
It will be interesting to see future studies on the effects low-dose, long-term radiation exposure on the intestinal lining. According to the Merck Manual, as well as many other sources, this tissue is extremely sensitive to ionizing radiation (Barnes, 1999, p. 101; Macnaughton, 2000; Nejdfors, et al., 2000; Thiagarajah, et al., 2000; Monti, et al., 2005; Francois et al., 2013). One recent study has already revealed that doses as low as 10 mSv may induce apoptosis, or death of cells, within the lower crypt of the small intestine (Umar, 2010). The lower crypt is part of the mucosal barrier (or lining) in our gut that protects us against pathogens from the external environment while at the same time ensuring we get nutrients from foods. Once the lining breaks down, a magnitude of adverse health effects may follow including leaky gut and malabsorption of nutrients.
The thyroid is also very sensitive to ionizing radiation. A study in 2005 concluded that occupational exposure to ionizing radiation is related to the risk of developing an autoimmune thyroid disease and that “the usage of thyroid protection shields by radiation workers is strongly recommended.” (Volzke et al., 2005).
Most studies that have been performed on crews researched the incidence and risk of cancer among pilots and flight attendants. Although it is difficult to pinpoint the exact cause, the two cancers that are consistently higher among crews are melanoma and breast cancer (Badrinath et al., 1999; Gundestrup & Storm., 1999; Rafnsson, et al., 2000; Rafnsson et al., 2001; Pukkala et al., 2002; Reynolds et al., 2002; Ott & Huber, 2006; Hammer et al., 2009; Sykes et al., 2012). Nearly 20 epidemiologic or similar studies of cancer incidence was published between 2000 and 2004, with many reporting increased risks of breast cancer among flight attendants and melanoma among pilots and flight attendants (Sigurdson & Ron, 2004). Studies have also shown pilots to have an increased risk of prostate cancer and myeloid leukemia, which is the type of leukemia induced by exposure to radiation (Band et al., 1996; Gundestrup & Storm, 1999).
In 2005, a review was initiated to determine if ionizing radiation could be a cause of melanoma. The study analyzed seven groups including nuclear workers, survivors of atomic bombings of Japan, recipients of medical radiation, and airline crews. Relative risks for leukemia were used to confirm the likelihood of exposure to ionizing radiation. Generally, the categories with elevated relative risks of leukemia had proportionately elevated relative risks of melanoma which suggests that people exposed to ionizing radiation may be at increased risk of developing melanoma (Fink & Bates, 2005).
A 2006 study proved that breast cancer increased by 40% among flight attendants and stated, “female flight attendants and women who fly frequently should be informed of this potential increase in risk.” (Salhab, & Mokbel). A meta-analysis that same year stated in its conclusion, “ …all airlines should, as some companies do, estimate radiation dose, organize the schedules of crewmembers in order to reduce further exposure in highly exposed flight attendants, (and) inform crew members about health risks…” (Buja et al., 2006).
As the meta-analysis from 2006 suggests, airlines should monitor radiation dose and educate crews of the risks involved. Airlines operating in the European Union are required to keep their crew’s annual effective dose under 6 mSv, airlines in Japan try to keep their crew’s exposure under 5 mSv, the Nuclear Radiation Commission require that employees are educated about the health effects of radiation, and health care professionals are recommended to wear dosimeter badges if they are at risk for exposures greater than 5 mSv (Bushberg, 2009). The U.S. airlines, on the other hand, neither educate their employees on radiation nor monitors the amount received. Although some unions have expressed concerns about the risks to crewmembers and passengers, the U.S commercial aviation community seems to disagree (Fisher & Jones, 2007, p. 32).
U.S. airlines do receive solar storm reports from the NOAA National Weather service (NWS), however when I asked several captains about these, most knew they were available but stated that they did not often see them in their briefings. A workshop was developed early 2007 (that included participants from the aviation community, federal government, and space weather community) after space weather storms in 2003, early 2005, and in the fall of 2006 demonstrated a growing need for discussion of the use of space weather forecasts. It was felt that the airlines’ “overly cautious response” to these storms showed “a lack of understanding and awareness” and highlighted “the lack of globally accepted and coordinated operational information and awareness (p. 3).” It was also pointed out that since “there is little understanding of space weather, there is little perception of the risks (p. 26).” There was a need to provide education at all levels (including dispatchers, ATC, pilots, crew, and passengers) and a need to make the space weather reports less technical and more easily understood (Fisher & Jones, 2007). That was 6 ½ years ago. Then, in April 2012, the same thing repeated itself. Another workshop brought together the same group of people (aviation industry representatives, regulators, and space weather forecasters) with the same conclusions; Space weather information should be communicated “in a manner emphasizing applicability, readability, and dispatcher comprehension”, and that “education is essential at all levels: dispatchers, air traffic control, pilots, crew, and passengers …” (Meehan & Kunches). Back in 2007, the airlines were “trying to understand why they should care about space weather.” Today, when the solar cycle is at its peak, it appears that this is still the case. In its 2006 Advisory, the FAA states that as long as air carriers respond to solar radiation alerts, ionizing radiation from the sun should not contribute enough radiation to exceed recommended exposure limits. But unless airlines understand about and agree that these storms can have significant effects on communications and the health of crews and passengers, how can they respond appropriately?
NASA is currently trying to build a better model called NAIRAS (Nowcast of Atmospheric Ionizing Radiation for Aviation Safety) that can predict the amount of both solar and cosmic radiation that flight crews and frequent fliers are exposed to on commercial airline flights. According to them, this model tracks individual aircrew exposure levels, provides airlines and FAA with necessary data to develop procedures for radiation exposure limits, provides time-critical data during solar particle events, and provides a database of radiation exposure levels. By implementing this system, airlines can balance the cost of changing flight paths against minimizing radiation exposure and health risks to crews and passengers (Mertens et. al., 2008).
Until all airlines decide to implement strategies that minimize risks, there are a few things we can do ourselves:
FAA system (CARI-6) that calculates effective dose rates from galactic radiation (past months)http://www.swpc.noaa.gov/rt_plots/pro_3d.html
NOAA Space Weather Prediction Center’s 3-day solar particle event chart. Particles greater than 100 PFU are considered moderate (S2 rating) and may expose passengers and crews to an elevated radiation risk.
NOAA Space Weather Prediction Centers website with current space weather conditions. If you click on “Alerts/Warnings”, then “email registration”, you can sign up for free SPE alerts.
NASA’s NAIRAS prototype that provides real-time predicted radiation dose rates. Click on “current rate dose” to get daily updates on four cross-polar routes: London-New York, Chicago-Stockholm, Chicago-Munich, Chicago-Beijing. This gives you an estimate of total radiation exposure in an easy-to-understand format.
NASA has also developed space weather apps for the iPhone (SpaceWx) and Android (NASA SWx).
In sum, crewmembers working long-haul, high-latitude flights around 1000 hours per year are exposed to about 7 mSv from galactic radiation alone, an amunt that exceeds the average amount other radiation workers are exposed to and seven times the annual amount recommended to the general public. In the event of solar storms, which are expected to peak this year, exposure to passengers and crews may increase by a factor of 10 or 20 per flight. There is also the possibility of ionizing radiation from thunderstorms, security scanners, and radioactive cargo. This is all in addition to the natural annual background radiation of around 3 mSv per year and medical imaging radiation that averages about 3 mSv, or more for crewmembers and passengers that have had CT scans. As if that is not enough, many crewmembers have to fly even more due to lowered wages and increased hours. Recently it has been confirmed that there is no safe level of ionizing radiation and that even low levels can cause cancer as well as other adverse health effects. New studies of low dose radiation over longer periods show a significant correlation between radiation dose and all causes of mortality. And a multitude of studies show high levels of the same cancers in crewmembers.
After learning all this, I have one question… With regards to flight crews and frequent fliers, what happened to the two fundamental principles for limiting radiation, justification and ALARA (keeping levels of radiation “as low as reasonably achievable”)? Hopefully things will change soon because I, for one, do not care to be another statistic in a future study on the detrimental effects of ionizing radiation on crews.