Carlcowkau From Hong Kong, joined Mar 2005, 23 posts, RR: 0 Posted (8 years 8 months 3 days 8 hours ago) and read 6431 times:
I really want to know how serious passengers will be after taking direct flight from Asia to America passing through the north pole with a huge amount of radiation. Any accurate measure of this? Since I've only heard of the problems from CX HKG-JFK. Lastly, anymore "pole-crossing" routes beside 1) CX HKG-JFK, 2) SQ SIN-EWR, 3) CO HKG-EWR, 4) AC HKG-YYZ??
[Edited 2005-04-12 21:28:44]
Looking forward to being in CX 747ADV and A388.....
TimRees From United Kingdom, joined Aug 2001, 353 posts, RR: 0 Reply 1, posted (8 years 8 months 3 days 7 hours ago) and read 6300 times:
Don't know if the risk is that large.
I'm not a radiation expert (just a doctor) but from what I understand crossing the North Atlantic from London to USA (at 35000ft) exposes the occupants of an aircraft the the same radiation as you would get from a standard chest x-ray (CXR) and most people would worry about having one of those. Sitting in front of your TV exposes you to a few CXR's of radiation a year and here in the UK living in Corwall (where there is a high granite concentration in the rock) exposes you to the same radiation of 3 CXR's/year.
When Concorde was in operation it had a special sensor for high radiation readings (it was at 50000ft+ of course) and if it exceeded the safe limit it had to decend.
If you think that aircrew are flying 1000's of hours yearly and (I believe) there is no proven link between an increased risk of cancer in aircrew compared the the general population (It has been postulated) I suspect the average flyer, who will only make these journies relatively infrequently, is at a lot less risk than if they smoked 20 cigarettes/day.
Sjg From United Kingdom, joined Apr 2005, 20 posts, RR: 0 Reply 2, posted (8 years 8 months 3 days 4 hours ago) and read 6143 times:
Hi, long time lurking first time post.
I believe there was a paper published in the lancet that concluded that there was an increased risk of leukaemia and some cancers in aircrew. Will try and find it.
Even if there was a risk in aircrew, it is likely to be small, and as you point out probably far less than the risk from smoking, sunbathing etc. The risk for the average infrequent flyer is probably very small indeed.
Sjg From United Kingdom, joined Apr 2005, 20 posts, RR: 0 Reply 4, posted (8 years 8 months 3 days 4 hours ago) and read 6098 times:
I am not an expert but as I understand it is cosmic radiation. Although you are also exposed on the ground, the level is much lower as it has been filtered by the atmosphere. The higher you go, the less atmosphere above you to filter the radiation and therefore the greater the risk. In the same way, as the ozone layer is depleted the intensity of the radiation increases.
The two biggest ozone holes are over the arctic and antarctic. Since there are more flights over the arctic, it is of greater concern to aviation.
USAFMXOfficer From United States of America, joined Nov 2004, 174 posts, RR: 0 Reply 5, posted (8 years 8 months 3 days 4 hours ago) and read 6087 times:
I think it has to do with higher electro-magnetic radiation. Think of the earth as a giant magnet with magnetic field lines bunching at the poles. This has taken tremendous effort to recall my very rusty physics knowledge....
44th Fighter Squadron Vampire Bats - 63 years of history
Carlcowkau From Hong Kong, joined Mar 2005, 23 posts, RR: 0 Reply 6, posted (8 years 8 months 2 days 21 hours ago) and read 5863 times:
From one of my relatives who is now a second officer of Airbus of CX, he said there's restriction by CX of no more than 2 round-trip flights in a month between HKG-JFK.
And I've just found a report from local newspaper, which said that the unit of cosmic radiation is mSV. A pregnant woman should not absorb over 1mSV in a year. The highest single-trip radiation of thoughout a year is 0.0938 mSV, therefore she's not recommended to take 5 round trips in the year. For normal passengers and crews, 4.8 mSV is the common limit for them in a year and it's equivalent to 25 round trips HKG-JFK.
The average amount of radiation of CX crews is 1.8-1.9 mSV, the highest cabin crew reaches 4.48mSV
Looking forward to being in CX 747ADV and A388.....
It has to do with the earth's spin and the resulting hadley and walker cells moving ozone depleting chemicals to the poles. Combine that with air borne ice particles that act as a catalyst bed and one has a reduced ozone layer. Combine this with the lack of a day/night cycle at the pole at certain times of the year (local summer) you have an excess further depletion (even elimination) of ozone and hence more radiation making it through. As other noted, a higher altitude means less atmosphere has absorbed the radiation. (O3 is great for UV absorption).
UA ORD-HKG...I flew this last year and we were very close to being exactly on the N. pole. I'd say just about any trans-pac flight from Eastern North America would go over/near the pole when winds are favorable (or should I say unfavorable to fly Westward).
Sometimes we don't realize the good times when we're in them
Sjg From United Kingdom, joined Apr 2005, 20 posts, RR: 0 Reply 13, posted (8 years 8 months 2 days 18 hours ago) and read 5682 times:
For anyone that's interested here is the reference to that paper I mentioned that found a higher rate of some cancers in aircrew:
"Gundestrup & Storm, Radiation-induced acute myeloid leukaemia and other cancers in commercial jet cockpit crew: a population-based cohort study, The Lancet, Volume 354, Issue 9195, 11 December 1999, Pages 2029-2031."
In a nutshell they found that air crew flying 5000h+ had a generally higher risk of cancer, in particular acute myeloid leukaemia. They also reported a higher rate of skin cancers - but this was thought to be due to all the time aircrews spend realxing on the beach at their destinations!
Quoting Carlcowkau (Reply 6): The average amount of radiation of CX crews is 1.8-1.9 mSV, the highest cabin crew reaches 4.48mSV
Do crews wear radiation tags like radiographers do? Also, does any airline have a maximum number of flight hours their crew can do per year to limit the radiation they are exposed to?
Carlcowkau From Hong Kong, joined Mar 2005, 23 posts, RR: 0 Reply 14, posted (8 years 8 months 2 days 12 hours ago) and read 5495 times:
Quoting Sjg (Reply 13): Do crews wear radiation tags like radiographers do? Also, does any airline have a maximum number of flight hours their crew can do per year to limit the radiation they are exposed to?
I don't think they would wear them.
For the maximum number of flight hours, I've never heard of such limit, but the Civil Aviation Department in Hong Kong is now keep tracking the radiation absorbed by crew. Captain M S DAVIS, the Chief of flight Standards, said that for those crews who reach 4.8 mSV in a year, they will be arranged to serve in routes with less radiation.
Looking forward to being in CX 747ADV and A388.....
Tockeyhockey From United States of America, joined Feb 2005, 940 posts, RR: 0 Reply 15, posted (8 years 8 months 2 days 9 hours ago) and read 5160 times:
Quoting COAMiG29 (Reply 3): may i inquire as to why there is radaition at the north pole?
i think it has to do with the magnetic poles -- they sheild those of us who live between the poles from cosmic and solar radiation, but expose the poles themselves to increased radiation. it has to do with how magnetic fields bend and move radiation, i think.
Sjg From United Kingdom, joined Apr 2005, 20 posts, RR: 0 Reply 16, posted (8 years 8 months 2 days 8 hours ago) and read 4708 times:
Done a little bit of reading about this. It seems that there are 2 main reasons for the level of radiation being higher at the poles:
1. Ozone depletion. As a result of the cold temperatures at the poles huge "polar stratospheric clouds" form. These provide a large surface area for chemical reactions to occur, which creates chemicals that degrade ozone. This lets more radiation, in particular from the solar wind, through.
2. Magnetic field. Electrons travel down the field lines, which enter the atmosphere at the poles.
So it seems everyone is right. Correct me if I am wrong though, wouldn't be the first time.
Getting this back to aviation, the ozone hole over the antarctic is far bigger than the arctic. Are there any routes that overfly the south pole?
Eilennaei From , joined Dec 1969, posts, RR: Reply 17, posted (8 years 8 months 2 days 7 hours ago) and read 4614 times:
What a depressing thread. People have absolutely no clue as to the basics of elementary (high) school physics. The composition of the Earth's atmosphere has NO relation to the Earth's magnetic field. The relative depletion of the ozone layer is due to the circumstances of the weather phenomena only -- the stagnation of upper atmosphere in winter, esp. over the mass of Antarctica whereby the ongoing chemical process of ozone depletion (& regeneration) becomes more evident.
What the thread starter was probably after was that the RADIATION shielding properties of the atmosphere weaken as the total mass of air thickens as you climb upwards. That shielding I S constant, i.e. the THICKNESS of the A I R layer is very much the SAME everywhere on the same level. The North Pole is no exception.
The ELECTRO-MAGNETIC phenomena going in the atmosphehe are typically evidenced by what is known as the Northern Lights, (Aurora Borealis). These do not appear at the magnetic poles only (please remember that the geographical and the magnetic poles are removed from each other), the actual range is far greater, depending on the Sun's activity. These, like any electro-magnetism, have NO verified physiological effect on any life. (The writer is one of the 1% of the Earth's inhabitants that have a chance to regularly witness the phenomenon, only if the city lights were all turned off some suitable time)
The ozone problem's physiology is not related to either one of the above. The matter is purely a problem of excess UV (Ultra Violet) radiation. Any type of aircraft skin (and windows) will stop this. In other words, one will not get sunburns inside an aircraft!
Sjg From United Kingdom, joined Apr 2005, 20 posts, RR: 0 Reply 18, posted (8 years 8 months 2 days 7 hours ago) and read 4577 times:
Quoting Eilennaei (Reply 17): The composition of the Earth's atmosphere has NO relation to the Earth's magnetic field
If you re-read what I posted I think you'll see that I never claimed the atmosphere influenced the magnetic field in any way.
The magnetic field may not have an effect on life (although there is also evidence that it does). However, if DEFINITELY does affect the path of the stream of electrons that make up the solar wind. Magnetic fields obvously affect the path of electrons, THAT is elementary high school physics.
The magnetic field of the earth looks like this:
Charged particles become trapped in the field and are attacted to the earth down the field lines in a spiralling motion. Therefore you are exposed to more radiation at the poles than elsewhere on earth, where the field shields us from charged particles. This is shown in this diagram:
Also remember that the atmopshere does not only absorb UV radiation, but all types including beta radiation (electrons & positrons). Therefore ozone depletion does have an effect, even if a small one, on the radiation we are exposed to.
SATX From United States of America, joined Apr 2005, 2840 posts, RR: 8 Reply 19, posted (8 years 8 months 2 days 7 hours ago) and read 4557 times:
Quoting Sjg (Reply 16): 1. Ozone depletion. As a result of the cold temperatures at the poles huge "polar stratospheric clouds" form. These provide a large surface area for chemical reactions to occur, which creates chemicals that degrade ozone.
The ozone layer is a naturally occurring phenomenon, but the comment above makes it sound as though ozone depletion is also strictly a natural occurrence. To my knowledge, the sudden and rapid depletion of the ozone layer in modern times is strongly linked to unnatural chemical accumulation from multiple manmade sources. Natural variations in the ozone level have not been shown to result in such drastic changes within such a short time frame.
- Edited for poor wording.
[Edited 2005-04-13 23:10:47]
Open Season on Consumer Protections is Just Around the Corner...
Eilennaei From , joined Dec 1969, posts, RR: Reply 20, posted (8 years 8 months 2 days 6 hours ago) and read 4537 times:
In fact any ill effects of electro-magnetic fields are not presently verified, many industries would be "interested" if they were, including the worldwide wireless communications industry.
Likewise, the universal gravity (matter weighs the same the world over) takes care of the fact that the atmosphere is in fact evenly distributed along the surface of the Earth. Whatever shielding is present, is present in the same quantity everywhere, relating to the "space" radiation that is in principle stoppable by the mass of the atmosphere.
I'm sorry to have upset anyone personally, it was not my intention, but I feel people are not thinking hard enough, and are not critical enough. But this is, after all, an "instant gratification" society...
I noticed the same, and edited into the text "relative" --> the relative depletion. I'm not denying -- I'm personally at risk all the time.
Sjg From United Kingdom, joined Apr 2005, 20 posts, RR: 0 Reply 21, posted (8 years 8 months 2 days 6 hours ago) and read 4523 times:
Quoting SATX (Reply 19): The ozone layer is a naturally occurring phenomenon, but the comment above makes it sound as though ozone depletion is also strictly a natural occurrence.
Sorry, should have worded that better. Of course you are right. The chemical reactions that lead to ozone being destroyed are caused by CFCs etc released into the atmosphere. That said, I think some degree of ozone detruction is a normal part of how the atmosphere maintains itself.
Back to the question I asked earlier, any polar routes over the antarctic that anyone knows of?
Sjg From United Kingdom, joined Apr 2005, 20 posts, RR: 0 Reply 22, posted (8 years 8 months 2 days 6 hours ago) and read 4507 times:
Quoting Eilennaei (Reply 20): In fact any ill effects of electro-magnetic fields are not presently verified, many industries would be "interested" if they were, including the worldwide wireless communications industry.
Sorry, think I am not explaining myself well. Didn't mean the magnetic field itself is dangerous - just the charged particles that are directed by it.
No worries, you didn't upset me. Am meant to be writing a paper about something completely different - little debate we got going here is a nice distraction .
Eilennaei From , joined Dec 1969, posts, RR: Reply 23, posted (8 years 8 months 2 days 6 hours ago) and read 4491 times:
Quoting Sjg (Reply 22): just the charged particles that are directed by it.
Those charged particles will be electrons. Their path will form a kind of invisible cable carrying current as in any "solid" cable, which in turn induces other current into telecomm and utility cables and wires --> keeps the repairmen busy during peak Sun activity. Another piece of electromagnetism at work, no more.
The magnetic field, whilst not dangerous in itself, does channel particles (not only electrons) to create radiation. Due to the nature of the earth's magnetic field this effect is most pronounced at the poles.
Back to aviation - anybody know of any antarctic routes?
25 SATX: Personally, if I were taking a once-a-year holiday to Asia from the USA, I would not hesitate to make use of a polar route simply on the basis of radi
26 Cha747: They taught me in med school that the magic radiation number is 1.21 Jigawatts In anycase, the Dept. of Pediatrics at Jefferson Medical College in Phi
27 Eilennaei: That medical abstract reference Sjg has found studies "hadron, lepton, and photon fields" that are a mystery, to me at least. All matter is made of ha
28 Eilennaei: To compare to the image in #18, here is a linked model of the Earth's magnetic field what I feel is more realistic: -eilennaei[Edited 2005-04-14 09:17
29 Antares: Sjg, There are no scheduled commercial flights that cross over the main Antarctic continent. Qantas has scenic Antartica flights that seldom venture v
30 Pelican: @Eilennaei Indeed Earth's magnetic field is shielding us from cosmic radiation. If you fly at a higher FL you will get a higher dose of cosmic radiati
31 Eilennaei: If we're talking about the cosmic radiation proper, it is not greater near the polar If regions as it comes from a seemingly uniform source outside ou
32 Lekohawk: Aurora are touched off by particularly strong instances of the "solar wind" (electrons and other elementary particles tossed off constantly by the sun
33 Eilennaei: I practiced what I preached and rethought. I gather the source of the non-background radiation near the poles is not the original solar wind, but the
34 Manu: Excellent debate! You all are doing well at not shooting the messenger and getting the facts straight. Now if we could only do this in an A vs B deba