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Tuesday, 4 September, 2001, 13:31 GMT 14:31 UK
Air quality academic quizzed
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Poor air quality in passenger aircraft cabins is endangering our health according to a Canadian academic.

Professor Martin Hocking, from the University of Victoria, says that passengers are at risk of catching diseases as serious as tuberculosis.

This, he says, is due to the constant recirculation of cabin air, which not only has lower than normal oxygen content, but also exposes travellers to viruses which are not removed by standard aircraft filtration.

However, his claims have been attacked by both industry groups and a leading aviation health expert, who say it has no foundation in science.

Is this simply scaremongering or are we at risk from low-quality air? Could diseases as serious as tuberculosis really be spreading inside aircraft cabins? Are airlines doing everything they can to reduce the risks?

Professor Hocking answered your questions in live forum.


Transcript:


Newshost:

Professor can I start first of all with a question from James Bignall in West London who asks: I fly frequently for work and I am not about to stop now without seeing some hard evidence to back up these claims. What evidence do you have to support what you are saying about the quality of air?


Professor Martin Hocking:

It has not been possible to give a quantitative statistical answer as to the possible increase in disease transmission. But the factors that would tend to support that are that aircraft have among the smallest available airspaces per person of any public space. So therefore people are packed closer together for long periods of time in aircraft than in any other public space. They also supply with the newer aircraft, a smaller amount of outside air per person than any other public space and that too with less air changes in a unit time one would expect the transmission rate to be somewhat higher.

But there is no definite statistical number that we can attach to that increased risk. It is fairly clear that there is an increased risk but what that number is we don't know.


Newshost:

And you feel that part of the problem is the re-circulation of the air within the cabin is it?


Professor Martin Hocking:

Well, the re-circulation itself probably doesn't contribute that much because the re-circulated air is passed through a very efficient filter - this is a called a HEPA - high efficiency particulate air filter and that is pretty good at capturing most particulate matter that might be in the re-circulated air. The main factor probably is the slight decrease in outside air volume that is pumped into the newer aircraft.


Newshost:

Mike Foreman in Portsmouth, UK asks: What precautions would you recommend we take when we fly in airliners?


Professor Martin Hocking:

If you can choose flights that are less full, you have a lower risk. If you choose aircraft that have a higher capability of pumping outside air than some of the newer aircraft, you should have less risk. Again it is not a hard line - you have more risk or less risk but it wouldn't guarantee that you wouldn't get ill and it wouldn't guarantee that you'd stay well.


Newshost:

But as travellers, can we find out which aircraft are better than others in this respect?


Professor Martin Hocking:

Yes, there is a report that has just come out that lists 20 specific aircraft and it gives the specifications for those. So that can be consulted for that type of information.


Newshost:

Jody Linbeck from London, UK asks: What about airline cabin and flight crews who clearly spend more time in planes than the rest of us? Are they likely to be more at risk?


Professor Martin Hocking:

They are and there is statistical evidence that they are ill more often. SAS has done a study of their cabin attendants versus their flight deck crew and they do show a higher incidence of illness among their cabin crew than the flight deck. So that would tend to support the fact that the flight attendants do have a higher risk.


Newshost:

Brian in Cleveland, Ohio, USA asks: A spokesman for the British Air Transport Association has called Professor Hocking's claims a scare story. Are they in denial?


Professor Martin Hocking:

Well I wouldn't call the information I have assembled scary. I would say it's a trend that I would like to see reversed but I wouldn't call it as alarming as perhaps your questioner is perhaps suggesting.


Newshost:

Dave Evans in Manchester, UK asks: As an airline cabin crew member on a major international airline for over 20 years, I have never suffered any serious contagious diseases. However, what worries me more, as far as airline crew are concerned, is the long-term effect of jet-lag, increased radiation levels and reduced oxygen over many years and its effect on life expectancy. Is there any research on any of this?


Professor Martin Hocking:

There is some research on the radiation risks and that is dependent on the altitude of the aircraft - the higher the altitude, the more the radiation risk. It is also a factor of the 11 year sunspot cycles - if you are at the peak of a cycle, you can get 10 to 20 times the radiation in a single flight than if you were at the minimum in a cycle. So those are things that perhaps a crew member doesn't really have much choice about but they are risk factors - there is no doubt about that.


Newshost:

Doctor Brian Spencer in Germany asks: I totally agree with your findings. As a frequent flyer, I have observed that after a flight I often pick up some mild cold or other. Certainly every time I have flown to America I have picked up a flu virus and I think that this is due to the long time period in the aircraft, the drier air and the fact that the aircraft (747) is much larger and therefore more chance of a passenger carrying a virus. You would agree that presumably?


Professor Martin Hocking:

Yes, although the 747 actually has a little larger airspace per person than some of the smaller aircraft. So while there are more passengers on it, the amount of airspace each passenger has is a little larger than would be the case with a smaller aircraft. So the larger number of passengers would increase the risk, the larger amount of airspace per person would decrease the risk, so it is probably not a major factor.


Newshost:

Jonathan Rose in Solihull, UK asks: What should we be asking the airlines to do to reduce the risks?


Professor Martin Hocking:

I think the important thing is to ask them to consider ways in which the outside air provided could be increased and ways that they might see managing to change the filters that are used to clean the re-circulated air rather more often than they now do.


Newshost:

Sue McIntosh in London, UK asks: Surely considering pollution levels in cities like London where I live, air quality in aircraft can't be all that bad in comparison.


Professor Martin Hocking:

She is probably quite right. I had somebody earlier today ask me about the London Underground and how that compared. Well, it is a different situation entirely. But sure, London city air is probably rated poorly relative to the air quality on aircraft.


Newshost:

Julian Hutchins in Taiwan asks: Would you agree that since smoking was banned in all international and long-haul flights, the amount of air circulated has been reduced? I believe that this in turn has added to the problem as the carriers have realised that great savings can be made through reducing the amount of air circulated during a 14 hour journey.


Professor Martin Hocking:

Yes that's true. There have been some articles published on measurements taken in smoking aircraft and in non-smoking aircraft and certainly the loss of the tracer evidence to passengers that cigarette smoke provides means that airlines can cut back on the outside air provided and it's still decreasing the nuisance aspect or the smell aspect of the cabin air quality. So yes, they have reduced the outside air provided coinciding with the elimination of smoking.


Newshost:

Marie in Limerick, Ireland asks: Airlines are unwilling to admit that there is anything wrong in relation to either bad air or deep vein thrombosis. What can be done to make the airlines more accountable and force them to consider the well being of their customers?


Professor Martin Hocking:

That I think can only come from public concern and the action of regulatory agencies to require changes to be made.


Newshost:

So you think that pressure from passengers could have an impact if people become concerned with issues like this?


Professor Martin Hocking:

It does in other areas of commercial activity. Oil companies have had boycotts by purchasers of fuel when they are unhappy with the oil companies' performance. So the same sort of thing could happen with the airlines.


Newshost:

Krishen in Harlow asks: What's the recommended level of fresh oxygen that should be pumped into an aircraft cabin? I experience redness of the eyes and lack of oxygen during long haul flights. Why should I put up with this? Can't the airlines increase it to 75% instead of 50% even if it costs more to do so?


Professor Martin Hocking:

That question is a little hard to interpret. But the American Society of Heating, Refrigeration, and Ventilating Engineers, has a standard for any enclosed space at ground level providing 15 cubic feet per minute of outside air per person in that enclosed space. I feel that is quite a reasonable standard to also apply to aircraft.


Newshost:

June Arbour in the UK asks: I read your report with great interest after what I experienced earlier this year. I have flown many times. The last transatlantic flight I took, despite drinking no alcohol and lots of water, when I arrived I felt very light-headed and wobbly until the following day which has never happened to me on any previous flight. When I came back I found I had developed bronchitis. I am healthy person and I was quite surprised. Do you think this was due to the flight?


Professor Martin Hocking:

Again that is hard to say. It could have been before or it could have been the flight. The other thing that of course raises one's susceptibility is if the questioner is anything like me - I am normally boarding a plane when I am quite fatigued already and fatigue is certainly a risk factor.


Newshost:

Another questioner asks: Does the length of journey time have a bearing on the risk involved? Presumably the risks are greater on long haul flights.


Professor Martin Hocking:

That would seem to be a safe assumption although I have become ill on some short flights too.


Newshost:

Finally Professor, you are just about to fly back to Canada. What concerns do you have about being stuck inside an aircraft cabin for 9 or 10 hours?


Professor Martin Hocking:

As I keep saying, I don't think it is an acute problem that we are experiencing with airlines - it's more of a chronic and borderline issue. So I just hope that they keep the fresh airflow at a good level for me and I should be alright.


Newshost:

But you think it is something that passengers should be concerned about?


Professor Martin Hocking:

Yes I take a few steps to reduce the exposure risk myself. One of the them that several doctors have proposed is to carry along a nasal mister filled with distilled water and several times in the flight when one feels one's nasal membranes are dry, just take a deep breath while pumping this nasal mist into those membranes. It certainly feels soothing - whether or not it helps reduce the risk of illness, I don't know.

See also:

04 Sep 01 | Health
Anger over air health claims
23 Oct 00 | UK
The seats of discontent
10 Jun 01 | Health
Airlines 'knew blood clot risk'
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