Radiation levels when flying

[237SJ]

The aviation industry say that people are exposed to minimal radiation when flying (you could say "they would say that wouldn`t they") but when I took my mum to hospital for radiotherapy there was a notice on the wall stating that 4 hours in a passenger aircraft is the same as a chest x-ray. Who`s correct? Any scientists out there like to enlighten?

[jake-the-peg]

Both are pretty small
Radiation dsoes are measured in Sieverts

Flying at 35,000 feet typically exposes you to about 6 microSieverts (that's 6 millionths of a Sievert) per hour
http://www.solarstorms.org/FAAAirlines.html

A chest X-ray exposes you to about 100 microSieverts so about 16 hours flying by my maths.

But the figures will vary depending on the type of X ray and how active the solar radiation is during the "flight".

What is a "safe" level of exposure depends - you could be walking about the street today and get hit by a single decay event from the granite in the pavement and it could give you cancer - but the odds against it are so extreme

The limit for public exposure is 1 millisieverts which is 1,000 Microsieverts

10 x-rays or 160 hours flying

That is still a very low level - the level set down to protect workers is still 20 times higher

200 x-rays worth

[237SJ]

Thanks Jake. My opinion was that the notice on the hospital wall was incorrect so that backs up my theory.

[dundurn]

The dosage received during flying increases with altitude (and obviously with duration). For this reason Concorde crews and military pilots both have been the subject of investigations in the past as to the cumulative dosage over the long term. Of more concern are the hours flight attendants work. They are not subject to the restrictions which apply to pilots and due to their lower hourly rates of pay are under more pressure to accept overtime (and even moonlighting for other airlines on off-duty periods).

[237SJ]

dundurn, pilots and cabin crew in the UK are both subject to the same rules. 900 hours per year maximum.

[dundurn]

In the UK we play by the rules - in other countries

1 they don't always and
2 they don't always have rules and
3 even where there are rules they aren't always the same as ours

e.g. FAA regs allow pilots to fly 1000 hours per annum. Most US airlines 'guarantee' flight attendants between 65 and 85 flying hours per month and there are opportunities to work more. (US Dept of Labor).

A further complication is that over pole flights have a radiation burden between 2 and 3 times equatorial level so staff who fly those routes on a regular basis may be picking up atypical exposure.

...and then there are the moonlighters...

on the other hand I agree with Jake - living in a country cottage in Cornwall without a ventilated foundation is much more risky!

[237SJ]

dundurn forgive me but I don`t think you know what you are talking about. And for the record, Concorde crews have never been subject to investigation

[igtretd]

237SJ...you may wish to look a this http://www.sciencedir...6a9ca98b1b904e0e3f815

[237SJ]

Thanks for your input igtretd. I`m not sure about the statistics though regarding Concorde pilots or any other pilots for that matter. With regards to my original thread, I still stand by my opinion that people that fly as pilots or cabin crew are exposed to radiation that is detrimental to their health.

[igtretd]

237SJ...First off I suggest you apologise to dundurn.

Secondly, the (statistically based) conclusions of the paper in the link do indeed show an increase in chromatic abnormality amongst Concorde pilots at levels estimated from 11 to 37 mSv.

[jake-the-peg]

I disagree 237SJ

The radiation levels that we are talking about here are very very small
If you look at igtrtd's link you'll see that they've presented this evidence despite the fact that the difference they found was *not statistically significant*

In other words they've done the research and basically didn't get the result they were looking for - they still have to write up but basically there's nothing there.

The background radiation in Aberdeen is very high due to all the granite 7.8m Sieverts

That's over a thousand hours flying.

Even when there's a solar flare the flying exposure only goes up by 50%

I am very doubtful that air crew have a significant health risk from low level radiation. I'd be more concerned about exposure to chemicals recirculated in the air

http://news.bbc.co.uk...d_8270000/8270978.stm

If I were working as air crew I'd be more worried about this than low level radiation

[igtretd]

jake-the-peg....read the abstract again...

'There was an eightfold significant increase of dicentric chromosomes in the Concorde group.' (relative to the controls)

The finding that was not statistically significant was the difference between supersonic and subsonic crews not the controls (who I assume were neither subsonic nor supersonic crew members)

As to whether this constitues a health hazard isn't a question of who whether you, me or 237SJ 'think' it's a hazard, rather it's a question of doing the study (which may have already been done for all I know). At first sight an eightfold increase would appear to warrant such a study.

[jake-the-peg]

Here's a full review by the Ocupational and environmental medecine people two years later that cites that first article

http://www.ncbi.nlm.n...25/pdf/v059p00428.pdf

They conclude

Several epidemiological studies point to increased incidence of certain cancers in air crew populations, but the link between cosmic radiation.

I think that it's highly likely that people are jumping to assumptions that this is due to cosmic rays.

Things like long term exposure to certain chemicals can also rapidly raise cancer risks and I would look here before making asumptions about cosmic rays.