Examination of Witnesses (Questions 80-99)
Dr Nigel Dowdall, Dr Mark Popplestone and Mr Roger
Wiltshire
26 JUNE 2007
Q80 Lord Patel: What is the main
constituent of these fumes chemically that would cause harm?
Dr Dowdall: We do not know because we have not
been able to test for it.
Q81 Lord Patel: What are you monitoring?
You said earlier on you are sampling when there is a likelihood.
What are you sampling for?
Dr Dowdall: We have done research programmes
in the past where we have measured cabin air in normal operation.
Q82 Lord Patel: For what?
Dr Dowdall: For a whole range of things, but
including volatile organic compounds and a whole range of those.
Q83 Lord Patel: Including organophosphates?
Dr Dowdall: Organophosphates have been looked
for. I believe the organophosphates element of this is something
of a red herring. I think that is an issue that people have latched
on to. I do not believe there is any significant evidence to suggest
that that is even plausible. But it is one of the concerns and,
therefore, with the research that is being planned specifically
to address this issue, organophosphates will specifically be looked
for. As I say, the difficulty we have is trying to capture a fume
event.
Q84 Lord Patel: Unless you monitor
all flights, how would you know that an event has occurred? Because,
by the time somebody reports it, presumably you cannot sample
anything.
Dr Dowdall: There is not the equipment available
that you can realistically monitor every flight all the time.
Dr Popplestone: This is one of the aims of the
research being proposed by the Aviation Health Working Group and
I am sure the Aviation Health Unit would be able to give you more
detailed information on that. The plan is that they will use a
variety of techniques, almost a very broad spectrum approach,
to identify what is there, if anything, during a fume event. The
fume events, when they occur, can be a duration of seconds or
maybe minutes. It is very short. So they are trialling a number
of detection devices, some that will pick up transient things
and some that will do long-term monitoring, to then analyse it.
I believe the idea then is, if they identify a particular compound
be it organophosphate, VOC or whatever, they can then develop
that and hone down to try to get more information on that specific
chemical. One of the difficulties is that we do know that if anything
is in there it is in very, very minute concentrations.
Q85 Lord Patel: It depends how toxic
it is.
Dr Popplestone: Yes, but we do not know what
it is. Anything that has ever been measured has, I believe, been
well below the threshold levels for known toxicity. Clearly, that
is one of the things that should come out of the research.
Q86 Lord Patel: There seems to be
disagreement amongst you whether it is easy to identify a fume
event or not.
Dr Dowdall: In the research context, the programme
is being set up specifically to try to maximise the opportunity
of capturing a fume event in a research programme. I am saying
that you could not routinely, on every British Airways flight,
have equipment on board just in case you had an event. You can
do it in research context and that is what we are supporting.
Some of the sampling equipment is very new. Some of it is, literally,
only now being developed.
Q87 Lord Patel: Do you have an opinion
on whether it is easy to identify a fume event?
Mr Wiltshire: My view on this—and I am
not an expert and I am not involved in in-flight operations—is
that the extreme end of a fume event is a visual one, where you
are seeing smoke, and that is probably seen by everybody on the
aircraft and that is almost a smoke event rather than a fume event.
The fume events people talk about are more where somebody smells
something that they feel should not be there. As Dr Dowdall has
said, everyone has a different perception of that, and a different
sensitivity to it. I am sure you will get different reports from
individuals smelling the same air as to what that air smelt like.
I think it is a very difficult area for us to assess because there
is not the technology available to suddenly capture that air at
that instant and analyse it. As we have been told, the technology
is only coming along now to allow us to do that.
Q88 Lord Patel: Are the reports you
have had related to newer designed aircraft or is it across the
board?
Mr Wiltshire: Again, the generality is that
the aircraft that have fume events historically have been older
aircraft, ones that are currently in the process of being phased
out. There are two particular aircraft that are involved. One
is a US-manufactured aircraft and one a UK-manufactured aircraft.
Both are relatively old. One, as I say, is in the process of being
phased out now and the other is in reduced use in the airline
business. The number of incidents, as I say, of fume events is
very small and that also makes it very difficult to capture a
fume event. It means that we will have to monitor a large number
of flights in order to capture just one event.
Q89 Earl of Selborne: Following up
on this point about how impractical it is to monitor a large number
of flights to catch just the occasional fume event—and that
I understand—presumably you can always analyse the HEPA
filters once they have come in for maintenance. That will tell
you what chemicals, if any, have been filtered out by these filters.
You have already explained in an earlier question that these filters
cannot by their nature be 100% effective, so it would give you
some indication of what these minute quantities might be.
Dr Dowdall: The filters are particulate filters.
They are designed to remove small particles. They are not designed
to remove chemical compounds. Small organic compounds would not
be retained by the filters. The other thing we need to bear in
mind is the ventilation flow rates on an aircraft are huge, so,
if you were trying to capture from that mass of air very tiny
amounts of compound, it would simply get lost.
Q90 Earl of Selborne: You would not
expect, therefore, to find on the filters—
Dr Dowdall: The filter would not capture organic
compounds—not chemicals. It is designed to capture particles.
Q91 Baroness Finlay of Llandaff: Would
the filters capture chemical molecules if they had a carbon layer
in them onto which the chemicals might be absorbed?
Dr Dowdall: In the technology we are looking
at to do the research, various materials are designed to absorb
compounds. If you are talking about routine use through the HEPA
filters, then I do not think they would capture them. I am not
an expert in filter design. In terms of the issue in which we
are interested, the exposure and health, the exposure comes from
the contaminant getting into the system, so the person is exposed
to it. It is no point then capturing it a bit later on. In terms
of using it as a means of identifying what people have been exposed
to, because of the volumes you are talking about it would be very,
very difficult.
Q92 Lord Howie of Troon: Following
on this last exchange of questions, I remind you that one of our
recommendations in the report now some years ago was that airlines
should carry out simple and inexpensive cabin atmosphere sampling
programmes from time to time and to make provision for spot-sample
collection in the case of unusual circumstances. How far have
you got in implementing this recommendation?
Dr Dowdall: In terms of sampling normal operations,
it is not something airlines routinely do but there have been
a number of research projects which have carried that out. The
European Cabin Air Project would be one. The National Academy
of Sciences in the States have looked at it. So there have been
a number of research projects. I do not think it is feasible to
do in routine use. The equipment that we use to do the sampling
has to be carefully set up. It has to be calibrated. It is not
something that is viable in routine operations. In terms of those
simple spot-checks, the technology has not been available. We
are talking about in a research context and we are not absolutely
sure that even what we have now will deliver what we are trying
to do. It is a case of what technology is available to do that.
It is not a simple process.
Q93 Lord Howie of Troon: The answer
to my question is not very far.
Dr Dowdall: I think that is a fair comment.
Q94 Lord Howie of Troon: You are
trying your best, are you?
Dr Dowdall: We are. We are working with the
Aviation Health Working Group, the Research Sub-Group. It is an
area of concern. I would like to be able to tell the pilots, "This
is what you are exposed to when we have a fumes event" be
it misting from de-icing fluid or a cabin air contamination.
Q95 Lord Howie of Troon: You hope
to get there some time fairly soon, do you think?
Dr Dowdall: We hope.
Dr Popplestone: Many airlines have volunteered
to help with the work that is being done on this through the Aviation
Health Working Group and the Committee on Toxicity. The Committee
on Toxicity, when they have been looking at the vast amount of
evidence they have been given in terms of air contamination, have
made some recommendations on research being done. The Aviation
Health Working Group, the Department of Transport are now taking
that forward. A lot of this technology is really very experimental,
it is frontline, but hopefully it will give the answers on what
is available. I know from Virgin Atlantic there was one project
done about two years ago monitoring Boeing 747 in routine operation,
but, as Dr Dowdall said, it was not a simple thing and all they
were able to do was monitor some simple things like carbon dioxide
and carbon monoxide levels, but it was a huge logistical exercise
to do. It is not a simple process doing it.
Q96 Lord Howie of Troon: Would you
be able to pick up any problems in the circulation of oxygen throughout
the aircraft or the pooling of CO2 near bulkheads or
in any other parts of the cabin?
Dr Dowdall: In British Airways we did some research
a few years ago looking at the Boeing 777 following some reports
from our cabin crew and we did quite a comprehensive sampling
programme comparing the 777 with the 747, the Jumbo. That looked
at sampling air both along the cabin and across the cabin at a
number of different points. In terms of oxygen, the volume of
air that passes through that is required for ventilation is such
that the oxygen level does not change, it does not significantly
decrease. In terms of CO2, again it was fairly consistent
throughout the cabin. We did not find any significant variation.
And you would not expect to with the way the circulation system
is designed and the mass of air that is flowing through the aircraft.
Q97 Lord Howie of Troon: Are you
satisfied with your monitoring of the ventilation system as a
whole?
Dr Dowdall: We operate the aircraft as the aircraft
manufacturers have designed and instructed us to do it. In designing
those aircraft the manufacturers have to meet the regulatory requirements
for ventilation, which, while the requirements are not comprehensive,
do cover specific items, for instance, the amount of air that
must be supplied to each passenger and crew member in the aircraft.
So, yes, those regulatory requirements have to be met and the
ventilation standards in aircraft are, I would suggest, significantly
higher than in most buildings.
Q98 Lord Patel: What is the oxygen
saturation normally of a flight in cruise?
Dr Dowdall: The percentage of oxygen at any
altitude is the same. It is 21%. The pressure varies with altitude.
If you take the maximum cabin altitude of 8,000 feet—and
the reality is that very few aircraft do get to 8,000 feet—the
reduced pressure is equivalent to about 15% oxygen. That is a
level at which the human body is perfectly able to function.
Q99 Lord Patel: Function as against
comfort, maybe.
Dr Dowdall: There is no effect on comfort. If
you look at ventilation and the respiratory physiology, at 8,000
feet, in a healthy human, you will see no physiological impact.
The supply of oxygen to the tissues is equivalent to what you
would see at sea level.
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