Naked Science Forum
General Science => General Science => Topic started by: Andrew K Fletcher on 05/05/2008 22:02:42
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Any Comments welcome. Please don't forget to rate my video [:I]
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fwww.freedigitalphotos.net%2Fimages%2Fphotos%2FRyanair_737.JPG&hash=0cd2d59ceb15a70338726dda25d5f79d)
A flight to Majorca from the United Kingdom, reveals increased risk of radiation using a scintillating GammaRae Pager detector.
Normal Background Radiation at Ground Level is 3 counts per second, increasing as the aircraft climbs to 15 counts per second with peaks measured at 17 counts per second.
While this poses little if any problems to a passenger going on holiday two or three times a year, it inevitably increases the risk of cancer to those working on regular flights.
Radiation in high-altitude flight is a complex mixture of particles that presumably come from stars, including our own sun. Protons, alpha particles, and heavier atomic particles from countless stars in our galaxy are sources of primary cosmic radiation.
In addition to the radiation coming from vast distances, the radiation from the sun, we call solar cosmic radiation, bombards our planet. When these particles enter the Earth's atmosphere, they collide with atoms of nitrogen, oxygen, & other particles in air producing secondary particles, mainly neutrons.
Many of the primary and secondary particles are absorbed by the Earth's atmosphere, However, at high altitudes during commercial aviation the radiation is of significantly
higher intensity than at ground level. Measuring all of the particles that enter an aircraft would prove difficult and would require some serious equipment.
The GammaRae Pager provides accurate measurement of gamma particles and many interactions are known to release these particles along with alpha beta and neutron, so although we do not measure all of the particles we can determine that the level of gamma radiation from collisions with other particles and direct collisions with the radiation monitor clearly show that high altitude flight is not without risks from increased radiation exposure.
Andrew K Fletcher
BBC News:
Tuesday, June 29, 1999 Published at 00:31 GMT 01:31 UK
Nine studies in North America and Europe have shown increased rates of cancer among those who work in aeroplanes.
Pilots are more likely to get colon, rectal, prostate and brain cancers, while flight attendants are twice as likely to suffer breast cancer.
Aircrew members who are pregnant could also be putting their unborn children at risk of diseases such as Down's syndrome and leukaemia.
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This info is not new; to wit, it can be found (qualitatively) quoted in GCSE Science text books.
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Maybe; but the video of the radiation monitor regestering the increased radiation is new and I cannot find another video anywhere else showing how it increases :) I took the monitor on the flight and recorded the video to show people that what they read in the text book is what we observe repeating the measurements.
Furthermore, there are a huge number of people flying who do not have the scientific background to study these effects but do have google and know how to view a video
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Hi Andrew
if you had the entire flight logged you could draw a graph of the CPS vs time. You could then superimpose the curve for altitude vs time and show how the two are related.
Chris
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It's a bit difficult trying not to alert the flight attendants to my experiment :) Didn't want to alarm anyone so during the flight I had to turn the camera off. But I agree that might be possible.
I stopped filming the counter after the aircraft began descending, noting that while flying at the cruise level for a 737 800 boeing approximately 37,000 feet.
Boeing 737 -700 Performance Typical cruising speed Mach 0.785. Maximum certificated altitude 41,000ft. 737-700 - Range with 126 pax 2852km (1540nm) or 6037km (3260nm)
Not entirely sure but think we were flying at 37,000 feet for most of the flight and the counter remained fairly stable at 14-15 counts per second with an odd anomaly over the mountains where it dropped to around 13 rising back once we had passed over them.
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Chris just thought, this experiment could provide us with data to produce a paper from NS, Maybe a few more of us flying to different locations could as you say record the raiation from different parts of the world? Obviously we need a counter that can have its alarm turned off so that it can be done without causing people undue concerns. That's why I chose the Gammarae Pager, its discrete and can be used with vibration or audio alarm or no alarm just the display. It does not however show alpha, beta or neutron radiation.
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Try this as a source of useful information.
http://www.ans.org/pubs/magazines/nn/docs/2000-1-3.pdf (http://www.ans.org/pubs/magazines/nn/docs/2000-1-3.pdf)
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Thanks for that link. A quick search on the PDF file did not find Gamma particles. Most refered to Alpha and neutron. Xray was not mentioned either, both of which can be measured using the Gammarae Pager. Alpha and beta have a low penetration rate, whereas Gamma goes right through the aircraft and the people inside it. Odd that it is not mentioned in that very informative paper?
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Gamma aren't particles like the others.
How do you know that your machine is only looking at gamma?
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Most of the radiation that is passing through the plane will be cosmic ray muons (μ), particles a bit like a very heavy electron. I would be very surprised if your detector could tell them apart from a gamma ray even if it doesn't detect alpha and beta particles as the detector is in a box.
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http://www.pksafety.com/pk_rae_gammarae.pdf
Link to a brief intro on the GammaRae Pager
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The intensity of cosmic rays (misnomer) varies with latitude as well as with altitude.
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Thanks for that link. A quick search on the PDF file did not find Gamma particles. Most refered to Alpha and neutron. Xray was not mentioned either, both of which can be measured using the Gammarae Pager. Alpha and beta have a low penetration rate, whereas Gamma goes right through the aircraft and the people inside it. Odd that it is not mentioned in that very informative paper?
I think that the paper is aimed at the 'already informed'; gamma is not very ionising - which is why it penetrates so easily. Dose for dose, it is not as harmful as Alpha and Beta but you can't screen against it easily and that is what makes it so nasty. The paper is discussing the actual sources of gamma photons (it does, actually, mention photons in the breakdown of the types of 'cosmic rays' arriving, on p33, last column).
The gamma photons which affect us have not all come from the Sun / outer space. They are generated in the upper atmosphere as high energy particles (see their list) from the Sun hit atmospheric molecules. Gamma photons created from muons extend much further down in the atmosphere than you would expect because special relativity gives them very long effective half lives. (School Science rules!)
The distribution with altitude, latitude and time is very wide!
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Thanks for the explanation makes sense now why I was able to measure gamma. The experiment while it may be boring to many people was fascinating to me. I had read about this and just wanted to see it for myself and record it so that others can see it also.
Chris mentioned videoing the whole trip. I have thought about obtaining an infra red receiver for my computer so I can transfer the data because the whole flight events should have been recorded in the monitor.
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I does amaze me that the lure of being in the air is so great that most people choose to ignore this particular risk.
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An interesting news article the other day was aiming at finding out whether it is exhaust fumes from the fuel and engines that might be causing health problems in those that fly regularly.
Is cabin air making us sick?
Charles Starmer-Smith
Page 2 of 3Last Updated: 10:48AM BST 29/05/2008 | Comments 56 | Have Your Say
At the very least this can cause drowsiness, headaches, flu-like symptoms and nausea — the kind of symptoms that Dr Nicola Hembry, a specialist in environmental medicine, says passengers may wrongly assume have been picked up from another passenger. At worst, air can be laced with a chemical, tricresyl phosphate (TCP), an organophosphate, or other toxic mixtures of chemicals that have been linked to serious respiratory problems, memory loss, neurological illnesses and even brain damage. http://www.telegraph.co.uk/travel/travelnews/759562/Is-cabin-air-making-us-sick.html?pageNum=2
Odd they never mentioned the radiation in the Telegraph article and I don't remember hearing it mentioned on the TV a few weeks ago. They appear to be trying to say its the cabin air that is causing all of these problems.
Perhaps we should start building 10 cm thick lead lined jets?
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At the prices they charge and the cost of fuel, they cannot afford to replace the air in the cabin with suitably warmed fresh air. They recycle it far to much. The cabins are chock full of other peoples' germs and other grot.
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Not being a physics whizzo like most of you replying to this thread, I'm probably thinking a load of old tat. But would the heated air in the engines have anything to do with the amount of particles? Or is it not hot enough for that?
At the prices they charge and the cost of fuel, they cannot afford to replace the air in the cabin with suitably warmed fresh air. They recycle it far to much. The cabins are chock full of other peoples' germs and other grot.
Apparently it's more harmful now they've stopped people smoking on aircraft [???]
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Flying from Bangkok, my friend got bitten severely by mozzies because they did not spray the Deet soon enough. Now theres a thought for them, if they are recycling the air and spray the Deet before taking off this may not be helping matters either.
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Concerns Mount Over Exposure
To Radiation on Airline Flights
By JESSE DRUCKER 2002
Staff Reporter of THE WALL STREET JOURNAL
Sandro Farina just got more nervous about stepping on an airplane -- and it's not because of security. The trading company executive recently learned from other fliers on the Web that his long-distance commute from Brazil to Hong Kong exposes him to something called cosmic radiation.
"I am really concerned," says Mr. Farina, who flies that route eight times a year.
Though not widely known, in-flight radiation is becoming a growing concern among researchers, crew members and the fliers who have to log thousands of miles a month. On any flight, radiation from stars penetrates the airplane, and experts say repeated exposure may be a health risk, similar to getting too many X-rays. The issue has not only led to changes at some foreign airlines, but prompted the FAA to set up a new radiation. And next year, the U.S. government plans to release findings on the long-term effects on crew members, covering everything from miscarriages to cancer.
But radiation's impact on frequent travelers has remained largely ignored. So with high-mileage fliers in mind, we conducted our own world-wide flight test, taking two high-tech radiation monitors along on trips as long as 15 hours and as brief as 34 minutes. In all, we logged 38,000 miles, crisscrossing the globe at various latitudes, longitudes and altitudes to get different readings.
The result: We found it takes a great deal of flying before exposure becomes much of a concern. Still, if you go to Asia a lot, take note of the Newark-Hong Kong route we took. It gave us our highest dose -- about three chest X-rays' worth. A once-a-month commute between Dallas and Chicago for a year works out to about eight chest X-rays. But East Coast shuttlers take heart: Flying a New York-Washington roundtrip every day for a week still wouldn't reach the level of one of those X-rays.
We also discovered that some shorter routes can actually expose fliers to more radiation than longer ones, and that doses rise quickly with altitude. (The higher you go, the less the atmosphere protects you.) Another issue: solar flares. During these rare occurrences, radiation levels can jump 20 to 100 times for as long as several hours.
To be sure, while our tests can be a guide for curious fliers, no one knows with certainty whether radiation is harmful at these levels. The federal government says the general public shouldn't be exposed to more than roughly 50 chest X-rays' worth a year from places like power plants and radiology offices (a level it estimates could cause cancer deaths in four out of 100,000 people). But workers in those industries can legally receive far more exposure. Based on our tests, you'd have to fly about 100,000 miles a year -- something about 72,000 Americans do -- to reach that 50 X-ray mark.
For decades, scientists have wondered about radiation's effects on aviators, but the issue has been gaining momentum due in part to growing concern from airline workers. Two years ago, regulators in Europe began requiring airlines there to track crewmembers' exposure levels and educate them about the possible risks. In the U.S., the Federal Aviation Administration has recommended that airlines educate crews about radiation (although only a few, including American and United, have produced brochures for them). And next year, the National Institute for Occupational Safety and Health plans to present new findings on the subject.
'They're Radiation Workers'
Though they acknowledge that cosmic radiation occurs, airlines and the FAA say they don't believe it's anything to worry about. The reason? The vast majority of fliers never come close to significant exposure. "There's no evidence to show that taking a few flights a year makes any difference," says FAA radiobiology researcher Wallace Friedberg. (Only one carrier, United, disputed our findings, saying the readings were generally 10% to 15% high.)
Still, consumer advocates believe fliers need more information, particularly super road-warriors who are stuck in planes many times a week. "They're radiation workers," says Robert Barish, author of "The Invisible Passenger: Radiation Risks for People Who Fly" and a medical physicist. "They're not in the airplane for pleasure."
In fact, many people are checking into the issue themselves: The FAA says as many as 1,500 people a month are using its Web site that calculates exposures on various routes. Some fliers are even tracking solar flares. "I was torn," says Marjorie McClelland, who postponed a flight to Kansas City, Mo., due to one. "My dad thought I was being a sissy."
For our test, our machines took readings in microsieverts, a common unit of measuring radiation. Experts say 1,000 microsieverts is equal to about 50 chest X-rays. Below, our journey:
New York-London
Miles: 3,500
Exposure: 42.9 microsieverts
At 6:30 in the morning, we passed the security checkpoint at New York's John F. Kennedy airport. In our carry-on: One Thermo Eberline 41H-B, to measure gamma rays, plus a Rembrandt neutron survey monitor, from Apfel Enterprises, to measure neutrons. As our gamma meter rolled through the X-ray scanner, its readings jumped.
By the time we hit our cruising altitude of 37,000 feet, where we'd remain for more than four hours, the gamma level had more than doubled what we measured at the airport screening machine -- in other words, we were getting more gamma radiation per minute in the air than our luggage got in the X-ray machine back at Kennedy. When we totaled it all up, we'd received the equivalent of two chest X-rays during this flight. "It's a little bit frightening," said Adam Brownstein, a Tokyo-based executive who flies about 100,000 miles a year.
Paris-Buenos Aires
Miles: 6,910
Exposure: 36.2 microsieverts
Heading through the security checkpoint at Paris's Charles de Gaulle International, we were asked to explain the two electrical contraptions in our bag. "Oh, radiation," the guard nodded, waving us on. (While security personnel at New York's JFK examined our meters closely, we passed through security at most airports without question.)
On matters of radiation, this flight actually confirmed something scientists had told us: Airtime or distance isn't necessarily the biggest factor in determining exposure. Flights running closer to the equator, for instance, have extremely low doses. (The Earth's magnetic field pulls radiation toward the poles, making the extreme points of the globe the most radiation-intense.) So although this marathon flight was twice as long as our New York-London trip -- clocking in at 13 hours -- it actually exposed us to less radiation than the New York-London route, which had taken us much closer to the North Pole.
Dallas/Fort Worth-Chicago
Miles: 725
Exposure: 6.6 microsieverts
We wanted to know how much exposure travelers face on a run-of-the-mill domestic flight. The answer: Not much, equal to about one-third of a chest X-ray. But on this and other flights, we also ran into a number of crew members who knew as little about radiation as their passengers.
That's not how it's supposed to work. Even though the airline has produced brochures, several American flight attendants we met say they had never seen them. Emily Carter, health coordinator for the Association of Professional Flight Attendants, says flight attendants have to know to ask for them. American says it has posted the information on the Web.
Newark-Hong Kong
Miles: 8,092
Exposure: 63.4 microsieverts
This is the trip Continental flight attendant Jacqueline Jacquet-Williams tries to avoid. We didn't learn this, though, until we were aboard with the doors locked. "I don't know enough, but I worry," she says. "I try to get rid of at least one of these flights a month because of radiation."
Just about a year old, this flight was one of a handful that U.S. airlines started steering over the North Pole, taking advantage of newly opened airspace over Russia. But that put us almost directly in the path of the strongest field of radiation above the earth. We fully expected our biggest dose on this 15½-hour polar flight.
And that's just what happened: About eight hours into our flight, as our Boeing 777 jet nosed away from the Arctic Circle and passed over Siberia, our gamma reading reached its peak, about 3.1 microsieverts per hour. By the time we had touched down in Hong Kong, we had measured a dose of radiation equivalent to three chest X-rays. (According to Continental: "The scientific evidence that we've seen demonstrates that any increased health risk caused by cosmic radiation is statistically negligible.")
Boston-New York City
Miles: 189
Exposure: Negligible
This commuter flight was our shortest at 34 minutes, and with a low cruising altitude of 16,000 feet, it returned one of our lowest readings. But on one level, we were lucky: Had we flown this route five days later, we'd have been in the air during a solar flare that erupted for several hours and boosted radiation to 20 times or more the usual levels.
How often do the flares occur? The ones that impact passengers may come years apart, but there were several last year, the peak of the 11-year "solar cycle" that's just ending. Critics including Dr. Barish say the FAA should require airlines to inform crewmembers and passengers, especially pregnant women, when significant flares occur; the FAA says it's exploring a system to alert airlines.
But Carol Kaehler isn't waiting. When her son was planning a trip to Australia, Ms. Kaehler said she counseled him against taking his baby daughter along because solar flares were peaking then. "I think worries about radiation are stretched," says the Florida artist and writer. "But more caution should be taken."
Video on Youtube showing Gamma Increasing with altitude.
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One of my university professors used to work with X-rays, and so, along with several people in the department, wore a "film badge" (for anyone who doesn't know, this is a plastic badge, about 35x25x8mm, containing a piece of photographic X-ray film and various small metal blocks, used to detect cumulative personal exposure over a week or two). The professor said that the only time his badge ever came back darkened was when he'd inadvertently taken the badge on a transatlantic flight. (I don't know for sure whether the badge would have gone through X-ray security screening or not, in this case.)
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It's interesting to note that this sort of story always compares radiation doses to chest Xrays. You might wonder why.
Here are some data on the radiation doses from various procedures.
http://www.radiologyinfo.org/en/safety/index.cfm?pg=sfty_xray&bhcp=1
As you can see, chest xrays are about the lowest dose on the list. They correspond to the normal background radiation that you would pick up in about 10 days anyway.
The highest exposure listed in AKF's post above (Newark - Hong Kong) is less than that, it's roughly equivalent to 6 days exposure to normal background.
So, unles you are flying something like half way round the world every week you are not even dounbling your normal background exposure.
The only people who might be at risk are the crew of the aircraft and some really determined high mileage travelers.
For the rest of us, it's just not an issue.
The people who came up with that stuff can't even do arithmetic.
Here's what they said
"Just about a year old, this flight was one of a handful that U.S. airlines started steering over the North Pole, taking advantage of newly opened airspace over Russia. But that put us almost directly in the path of the strongest field of radiation above the earth. We fully expected our biggest dose on this 15½-hour polar flight.
And that's just what happened: About eight hours into our flight, as our Boeing 777 jet nosed away from the Arctic Circle and passed over Siberia, our gamma reading reached its peak, about 3.1 microsieverts per hour. By the time we had touched down in Hong Kong, we had measured a dose of radiation equivalent to three chest X-rays."
OK 3.1 µSv/Hr (and that's a peak, not an average) for 15.5Hrs would give 48 µSv in total
The data on the webite I posted above gives a single chest Xray as about 100µSv.
There's a bit of variation on the dose from an Xray, but I doubt its a factor of a little over 6
This looks like scaremongering to me.
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Attention seeking.
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If that had a noun you could turn it into a sentence.
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What's wrong with a clause between friends? Or it may just be a phrase; the verb being in participle form.
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Is it a Santa Clause?
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Or a sanity clause (Groucho Marx?)
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It's interesting to note that this sort of story always compares radiation doses to chest Xrays. You might wonder why.
Here are some data on the radiation doses from various procedures.
http://www.radiologyinfo.org/en/safety/index.cfm?pg=sfty_xray&bhcp=1
As you can see, chest xrays are about the lowest dose on the list. They correspond to the normal background radiation that you would pick up in about 10 days anyway.
The highest exposure listed in AKF's post above (Newark - Hong Kong) is less than that, it's roughly equivalent to 6 days exposure to normal background.
Possibly, though the FDA appears to believe a chest x ray is .02 mSv rather than .1 mSv:
http://www.fda.gov/cdrh/CT/risks.html (http://www.fda.gov/cdrh/CT/risks.html)
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NASA first investigated the issue in the 1960s and 1970s when it was studying the feasibility of high-altitude supersonic commercial aviation transport, Mertens said. At the time radiation exposure during flight was deemed a negligible health concern for commercial aircraft at cruising altitudes given what was known about radiation and the number and types of flights common at that time.
Concerns have grown for three primary reasons. Pilots log twice as many flight hours now as then, while flight attendants typically log more hours than pilots. Epidemiological studies have shown this type of exposure to be more damaging than previously thought. And, the number of polar flights is increasing, Mertens said.
Airlines prefer polar routes – for instance, for certain U.S.-to-northern Europe or U.S.-to-Asia routes – because it's a shorter route with reduced head winds, creating fuel savings of tens of thousands of dollars per flight.
Preliminary research indicates that passengers and crews are being exposed to more radiation than previously thought, especially during significant solar events. Mertens analyzed data from a strong solar storm around Halloween 2003 and found that passengers on polar flights – for example from Chicago to Beijing – were exposed to radiation higher than the limit recommended by the International Commission on Radiological Protection. In addition, not including new features in the model such as magnetic storm effects on Earth's magnetic field underestimated the exposure during that storm by a factor of four.
http://www.nasa.gov/topics/earth/features/AGU-NAIRAS.html
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Assuming that factor of 4 applies to all flights (which it doesn't) would mean that, rather than having to fly halfway round the world every week to double your exposure compared to normal background, you would only have to make the flight every month. Of course, it would be difficult to shcedule all your flights during major solar storms.
Still hardly worth panicing about for most of us.