Toxic Cabin Air/Aerotoxic Syndrome
Long term the only solution is electric pumped pressurization, it would make the engines run more efficiently too.
It would be a result rather than a solution to fume events.
In the end there would still be alleged fume events and human maladies searching for a linked cause
Perhaps people should be careful what they wish for. EASA could easily (make up) regulate a life time safe exposure limit after which flight even as a passenger on bleed air pressurized turbojets was severely constrained. It happens in other industries.
Long term the only solution is electric pumped pressurization, it would make the engines run more efficiently too.
Long term the only solution is electric pumped pressurization, it would make the engines run more efficiently too.
Re efficiency, you are still using engine power to drive electric or hydraulic compressors with the attendant electrical, mechanical and thermodynamic losses.
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I think it is simpler to isolate oil in the air from a compressor especially one where a more benign lubricant could be used compared to the use of 7th stage air from within an engine lubricated using a 'total loss' oil system.
Another thing to be considered is the temperature of engine bleed air versus the output of a motor-driven cabin air compressor. Engine bleed air is hot to say the least and can decompose engine oils as well as vaporize it. The compression ratio of a motor-driven cabin compressor is far lower, hence output temps would be too and I would think its ability to break down the oil. Agreed, I do not want to breath undecomposed oil either..
APU bleed air and main engine bleed air can also decompose deicing glycol as I have seen where an APU was used to run the air conditioning during deicing and ingested deicing fluid. We had a return to the gate with a lot of nauseated pax.
APU bleed air and main engine bleed air can also decompose deicing glycol as I have seen where an APU was used to run the air conditioning during deicing and ingested deicing fluid. We had a return to the gate with a lot of nauseated pax.
Ian
What current turbine engine uses a 'total loss' oil system? Because the ones I'm familiar with are quite the opposite, with extremely low oil consumption rates when healthy (and any lube system can loose oil when it's damaged).
Turbine engines typically consume far more oil when operating at low power/idle - the lube systems use pressure differentials to keep the oil where it's supposed to be and that doesn't work as well with low power and low pressure differentials. That means that an aircraft taxing around an airport typically consumes more oil than it will during cruise.
If anyone was really interested in the subject, the absolute first thing they'd do is start sampling the air around large airports - lots of aircraft operating engines at low power and consuming lots of oil.
That so far no one has tells me everything I need to know.
What current turbine engine uses a 'total loss' oil system? Because the ones I'm familiar with are quite the opposite, with extremely low oil consumption rates when healthy (and any lube system can loose oil when it's damaged).
Turbine engines typically consume far more oil when operating at low power/idle - the lube systems use pressure differentials to keep the oil where it's supposed to be and that doesn't work as well with low power and low pressure differentials. That means that an aircraft taxing around an airport typically consumes more oil than it will during cruise.
If anyone was really interested in the subject, the absolute first thing they'd do is start sampling the air around large airports - lots of aircraft operating engines at low power and consuming lots of oil.
That so far no one has tells me everything I need to know.
Tricky stuff. It'll be interesting to see how it all pans out.
AFAIK, the only legacy I have, at the age of 75, from noisy, oily ships engine rooms and noisy, oily aircraft is tinnitus.
I know y'all thought I was a 'know it all' 30yo but I'm really a 'know FA' old barsteward
AFAIK, the only legacy I have, at the age of 75, from noisy, oily ships engine rooms and noisy, oily aircraft is tinnitus.
I know y'all thought I was a 'know it all' 30yo but I'm really a 'know FA' old barsteward
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As far as I am aware no-one has run a control measure of outside air all the measurements have been made with a degree of 'confirmation bias' so measures are taken within the cabin as the 'only source' of oily fumes could be from the compressor. And of course swabbing the seats will find traces of the oil contaminants in any aircraft that has taxied up behind another.
Just walking around an apron or down the jetway, smelling the kerosene and other fumes, it becomes obvious that there are a multitude of unmeasured sources. Including, sitting in the departure queue ingesting exhaust from the aircraft ahead and 'conditioning' the cabin air with that. Doesn't matter how good your seals are in that case.
Just walking around an apron or down the jetway, smelling the kerosene and other fumes, it becomes obvious that there are a multitude of unmeasured sources. Including, sitting in the departure queue ingesting exhaust from the aircraft ahead and 'conditioning' the cabin air with that. Doesn't matter how good your seals are in that case.
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Having suffered from this myself, some years back,and still have the odd migraines,2 people,Susan Michaelis( a Medic) and Tristan Loraine(Ex BA) formed an Aerotoxic Association with John Hoyte in the chair,with whom I used to fly!They started the ball rolling a full decade ago with little or no results as the Officialdom stated the Historical Data Base was not sufficient to enable the" Authority"to make a prognosis of any long term health problems!!That is exactly what the Lords and Masters of said Authority said to my Wife down at the Beehive Gatwick,when they removed my licence medical-Luckily just before I was due to retire.Meanwhile a LOT of my old mates have succumbed to a number of cancer related or brain related terminal health problems.
Maybe,at last, something may happem.
Maybe,at last, something may happem.
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Oh Yes!!!A Senior moment,but what I meant to add was the French Air Force have experimented with a Vegetable Based Oil that does not have the Carthegens in it,and have obtained reasonable results for Engine Life.These chemicals ,particularly in MobilJet 2,have the capacity to prolong engine life.In BAe years ago on the HS125,we used MobilJet2 to try to prolong the Solar APU which used to have a life of 2/3rds of 5/8ths FA,but failed and the Garret APU was then used and lasted a much longer time,as a result of which MobilJet 2 was used for both the Vipers(Total Loss Oil System) and the Garret 731,with minimal affect on Pax and Cabin.However the more modern Engines seem to churn out a far greater amount of Carsonagenic fumes from Organophosphates.I have not seen any comments with actual Airlines trying a vegetable based engine oil,so maybe no one else except the Fench have done so??
I rather think that's missing the point.
The aim is to stop oil residues contaminating the cabin air at all, not to substitute a more benign regime that emulates a flying chip shop.
The aim is to stop oil residues contaminating the cabin air at all, not to substitute a more benign regime that emulates a flying chip shop.
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London International Cabin Air Conference 19/20 September 2017
This industry supported conference is an essential two-day event, providing excellent networking opportunities for those seeking to understand the historical aspects of contaminated air, the flight safety implications, the latest scientific and medical evidence investigating the contaminated air debate and the solutions available to airlines and aircraft operators.
This important international conference mapping the business, regulatory and technical solutions to cabin air contamination, will be the most in-depth conference ever held on this topic.
September 19/20 2017
https://www.aircraftcabinair.com/
This important international conference mapping the business, regulatory and technical solutions to cabin air contamination, will be the most in-depth conference ever held on this topic.
September 19/20 2017
https://www.aircraftcabinair.com/
Article in The Economist (of all places)
https://www.economist.com/blogs/gull...ld-your-breath
"A recent study from the University of Stirling and the University of Ulster reveals the scale of the problem..."
"A recent study from the University of Stirling and the University of Ulster reveals the scale of the problem..."
https://www.economist.com/blogs/gull...ld-your-breath
"A recent study from the University of Stirling and the University of Ulster reveals the scale of the problem..."
"A recent study from the University of Stirling and the University of Ulster reveals the scale of the problem..."
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The problem nowadays is that there are so many publications that you can pretty much publish ANYTHING. If you don't believe me, a skeptic blogger recently published a complete bogus paper, in THREE different journals, based on midichlorians - yes, the ones from The Force in Star Wars. He even authored them as Dr. Lucas McGeorge and Dr Annette Kin 
The publication quoted in the Economist appeared in PUBLIC HEALTH PANORAMA. So, how do we know how that journal ranks in the scientific world? A good place to start is ranking sites such as EIGENfactor or SJR. So how does it rank? Well... It doesn't. Searching for that name returns no result.
So why hasn't this study been published in a reputable journal? Well I'm not an expert in this particular field, but even a cursory look at the paper reveals serious problems. For example what they describe as "Study A" is based on 14% of BAE146 pilots having filled in a health questionnaire (no randomisation, not control group, etc). For those who reported long term health effects, the paper provide a list of ailments and their occurrences. It pretty much reads "ailment A: 1 case; ailment B: 1 case; ailment C: 1 case" etc. So what you have a long list of different health effects that has been clumped together to form a hypothesised "syndrome". I could go on, but you get the idea.
I also looked at the publication list of the author's first paper and the pattern of publishing in very minor journals is clear.
I am not a manager, engine manufacturer employee, etc. I am your average line pilot. With a decent scientific background. Does journal ranking mean everything? No. Does the very poor quality of the study, IMHO, mean that no crew or passenger has ever been affected by fumes? No. But if you're going to worry the paying public and air crews, please back it up with sound scientific data.
The publication quoted in the Economist appeared in PUBLIC HEALTH PANORAMA. So, how do we know how that journal ranks in the scientific world? A good place to start is ranking sites such as EIGENfactor or SJR. So how does it rank? Well... It doesn't. Searching for that name returns no result.
So why hasn't this study been published in a reputable journal? Well I'm not an expert in this particular field, but even a cursory look at the paper reveals serious problems. For example what they describe as "Study A" is based on 14% of BAE146 pilots having filled in a health questionnaire (no randomisation, not control group, etc). For those who reported long term health effects, the paper provide a list of ailments and their occurrences. It pretty much reads "ailment A: 1 case; ailment B: 1 case; ailment C: 1 case" etc. So what you have a long list of different health effects that has been clumped together to form a hypothesised "syndrome". I could go on, but you get the idea.
I also looked at the publication list of the author's first paper and the pattern of publishing in very minor journals is clear.
I am not a manager, engine manufacturer employee, etc. I am your average line pilot. With a decent scientific background. Does journal ranking mean everything? No. Does the very poor quality of the study, IMHO, mean that no crew or passenger has ever been affected by fumes? No. But if you're going to worry the paying public and air crews, please back it up with sound scientific data.
If airframe and engine OEMs were key in the programme there would be even faster criticism and no doubt accusation of this welcome event being some form of cover-up. Do you seriously believe airframe and engine manufacturers will not be present and interested?
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Permafrost_ATPL makes a very good point, even a cursory glance at this study throws up a lot of potential problems.
Public health panorama is an OK journal but is quite low-ranking. It's not one where I'd expect to see ground breaking research - you'd send that somewhere better. If you see ground breaking research in a journal like this then it should set alarm bells ringing. It's also worth pointing out that pretty much the same research (at least, it contains the same studies without any changes) has been published before. Maybe I miss something, but I don't see anything new in this 'new' paper.
The studies also seem to be expecting a result and then going out to prove it. As Permafrost_ATPL says, there's absolutely no control studies done, no monitoring of other groups. Avoiding that bias is one of the first things you are taught as a scientist. The entire paper is based around positive selection bias, as a researcher it really makes me cringe to see stuff like that.
I've said it before and I'll say it again: This type of pseudo-scientific study undermines the actual evidence for health problems associated with cabin air. It's easy to dismiss other evidence when you also see this type of rubbish being published.
What we need is proper science, proper evidence and an in-depth study to understand both the prevalence of fume events and the effect that these have upon crew. What we have is a bunch of people who appear to come up with the conclusion first and then seek evidence to justify it. This is the worst kind of bad science.
Public health panorama is an OK journal but is quite low-ranking. It's not one where I'd expect to see ground breaking research - you'd send that somewhere better. If you see ground breaking research in a journal like this then it should set alarm bells ringing. It's also worth pointing out that pretty much the same research (at least, it contains the same studies without any changes) has been published before. Maybe I miss something, but I don't see anything new in this 'new' paper.
The studies also seem to be expecting a result and then going out to prove it. As Permafrost_ATPL says, there's absolutely no control studies done, no monitoring of other groups. Avoiding that bias is one of the first things you are taught as a scientist. The entire paper is based around positive selection bias, as a researcher it really makes me cringe to see stuff like that.
I've said it before and I'll say it again: This type of pseudo-scientific study undermines the actual evidence for health problems associated with cabin air. It's easy to dismiss other evidence when you also see this type of rubbish being published.
What we need is proper science, proper evidence and an in-depth study to understand both the prevalence of fume events and the effect that these have upon crew. What we have is a bunch of people who appear to come up with the conclusion first and then seek evidence to justify it. This is the worst kind of bad science.
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In a seminal, instant classic article John P. A. Ioannidis shows Why Most Published Research Findings Are False.
He essentially argues that the only valid findings are of meta-analysis where multiple reproducible studies are used as the basis of a larger study of these studies.
Even Richard Horton, editor of The Lancet, says: up to half of all research may be false:
There is a crisis in science, particularly the lack of reproducibility.
He essentially argues that the only valid findings are of meta-analysis where multiple reproducible studies are used as the basis of a larger study of these studies.
Even Richard Horton, editor of The Lancet, says: up to half of all research may be false:
...
The case against science is straightforward: much of the
scientific literature, perhaps half, may simply be untrue.
Afflicted by studies with small sample sizes, tiny effects,
invalid exploratory analyses, and flagrant conflicts
of interest, together with an obsession for pursuing
fashionable trends of dubious importance, science has
taken a turn towards darkness. As one participant put
it, “poor methods get results”. The Academy of Medical
Sciences, Medical Research Council, and Biotechnology
and Biological Sciences Research Council have now put
their reputational weight behind an investigation into
these questionable research practices. The apparent
endemicity of bad research behaviour is alarming. In their
quest for telling a compelling story, scientists too often
sculpt data to fi t their preferred theory of the world. Or they
retrofit hypotheses to fi t their data. Journal editors deserve
their fair share of criticism too. We aid and abet the worst
behaviours
...
The case against science is straightforward: much of the
scientific literature, perhaps half, may simply be untrue.
Afflicted by studies with small sample sizes, tiny effects,
invalid exploratory analyses, and flagrant conflicts
of interest, together with an obsession for pursuing
fashionable trends of dubious importance, science has
taken a turn towards darkness. As one participant put
it, “poor methods get results”. The Academy of Medical
Sciences, Medical Research Council, and Biotechnology
and Biological Sciences Research Council have now put
their reputational weight behind an investigation into
these questionable research practices. The apparent
endemicity of bad research behaviour is alarming. In their
quest for telling a compelling story, scientists too often
sculpt data to fi t their preferred theory of the world. Or they
retrofit hypotheses to fi t their data. Journal editors deserve
their fair share of criticism too. We aid and abet the worst
behaviours
...
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Fumes after engine start?
What are people's thought on the fact we are starting engine's on push back, so going into the fumes, where oil vapours could be, then turning on the packs to gulp it all in? I notice the acrid stink, to the point it bites my throat.sometimes after a week I wonder if it's fatigue that makes my aching limbs or something else
I notice the acrid stink, to the point it bites my throat.sometimes after a week I wonder if it's fatigue that makes my aching limbs or something else
Also equally common in everybody's lives
Association does not equal causation.
We await hard statistical validated scientific data to discuss this kind of subjective observation further.