Aerotoxic syndrome is the alleged short-term and long-term ill-health effects that are attributed to exposure to cabin air that has been contaminated with atomized engine oils or other chemicals. The documentary film Welcome Aboard Toxic Airlines suggests the term was first suggested in 1999 by members of an electronic global ‘egroup’ called Aerotox.
As of 2009 this syndrome is not recognized in medicine. There is no good evidence of adverse effects for normal travellers. An assessment by the UK's House of Lords Science and Technology Committee found that the claims of health effects were unsubstanbtiated. An update in 2008 found no significant new evidence, but a 2010 case in Australia (alone among all reported cases) found that oil vapor in cabin air had caused health effects in a flight attendant.
Potential sources of contamination
Modern jetliners have an Environmental Control System (ECS) that manages cabin air. Some of the air is recirculated, while the remainder is drawn from the outside, typically via compressed engine bleed air. Airborne contaminants may potentially originate from substances used in the maintenance and treatment of aircraft, including seasonal chemicals such as de-icing fluids, or from the ECS systems.
A service information leaflet from the UK-based Committee on Toxicology (COT) provided a list of possible sources of poor-quality cabin air. Some of the items on that list include:
- Underfloor hydraulic leaks.
- Ingestion of deicing fluid into APU inlet.
- Periodic maintenance task that is required to clean the forward galley oven.
- Inappropriate or excessive use of dry ice by caterers.
- Toilet fluid spillage, leakage and also unapproved mixing of different disinfectant fluids within the toilet.
- Leakage of the rain repellent system, or rain repellent contamination within the cabin or flightdeck.
- Spillage within baggage bays.
- Items stowed in overhead baggage bins.
Jet engines require synthetic oils for lubrication. These oils contain ingredients such as tricresyl phosphate (TCP), an organophosphate, that could possibly be toxic to humans in large quantities. Engine bearing seals are installed for the purpose of ensuring that critical engine bearings are continuously lubricated, and also to prevent engine oil from leaking into the compressed air stream. If a bearing seal fails and begins to leak, depending on the location of the seal, some amount of engine oil may be released into the compressed air stream. Oil leaks may be detected by odour or, in more serious cases, by smoke in the cabin. This is known in the industry as a fume event.
Cabin air contamination events
The term was used by a yearlong Australian Senate Investigation in 2000, which noted "successful applications for workers’ compensation for illness attributed to fumes on the BAe 146," "received approximately 20 individual submissions describing symptoms experienced by crew members and attributed to oil fumes leaking into the aircraft cabin," and concluded that "the issue of fume contaminants should also be considered a safety issue with regard to the ability of cabin crew to properly supervise the evacuation of an aircraft and the ability of passengers to take part in an evacuation".
On 5 November 2000, both the pilot and co-pilot of a Jersey European Airways BAe 146 became unwell while landing at Birmingham International Airport, with both becoming nauseous, and the pilot experiencing double vision and having difficulty judging height. Despite this, he managed to land the aircraft safely. "The first officer and commander were taken to hospital and examined, but no abnormalities were found." The subsequent incident investigation report concluded that "There is circumstantial evidence to suggest that the flight crew on G–JEAK were affected by contamination of the air supply, as a result of oil leakage from the auxiliary power unit (APU) cooling fan seal into the APU air stream, and into the ECS system ducting. This contamination allowed fumes to develop, a proportion of which entered the cabin and cockpit air supply."
That same AAIB Report also noted that both the captain and the first officer had visited the forward toilet, before the onset of their symptoms. About the same time of the G-JEAK incident, another operator reported overuse of a disinfectant (formaldehyde) for the toilets and to clean the galley floor and then inhalation of the fumes from that chemical, would produce the identical symptoms reported by both the captain and first officer of G-JEAK. "The CAA notified UK Operators at that time (CAA ref. 10A/380/15, dated 2 August 1996) of this potential hazard, as the misuse of this agent was apparently widespread."
The alleged ill-health effects that have been reported include cognitive problems, dizziness, disorientation, nausea, breathing difficulties, anxiety, mood swings, malaise, diarrhoea and various other neurological problems, particularly related to the autonomic nervous system. UK government research states that adverse health effects of short duration do occur, but although it cannot rule it out, says that the available evidence is unable to conclude a link to long-term symptoms.
Aviation Organophosphate Information Site (AOPIS) is a non-profit group set up by airline crews in Australia in 2001. AOPIS provides campaigns and information by way of articles, scientific papers, research papers, governmental policy and a documentary, on medical and flight safety issues relating to contaminated air exposure on commercial and military aircraft.
In 1986, the United States Congress commissioned a report by the National Research Council (NRC) into cabin air quality. The landmark report recommended a ban on smoking on aircraft in order to improve air quality, which was brought into effect by the FAA soon after.
Ongoing research commissioned by the UK government's Department for Transport (DfT) found no link to long term health. In its response to the many complaints received "from a number of witnesses, particularly the Organophosphate Information Network, BALPA, and the International Association of Flight Attendants, expressing concerns about the risk of TOCP poisoning for cabin occupants, particularly for crew who might be subjected to repeated exposure in some aircraft types, as a result of oil leaking into the cabin air supply," the UK Parliament's Select Committee on Science and Technology, concluded:
- "This question - including the potential effects on aircrew from any long-term exposure - has been looked at in much greater detail by a Committee of the Australian Senate inquiring into particular allegations of such contamination in the BAe 146. Although its Report referred extensively to cabin air quality and chemical contamination in the aircraft, and recommended that the engine lubricating oil used (a Mobil product) be subjected to a further hazardous chemical review, it made no specific points about TCP or TOCP that have given us additional concerns. The absence of confirmed cases of TOCP poisoning from cabin air and the very low levels of TOCP that would be found in even the highly unlikely worst case of contamination from oil leaking into the air supply lead us to conclude that the concerns about significant risk to the health of airline passengers and crew are not substantiated."
According to a report by Prof Michael Bagshaw, visiting professor of aviation medicine at Kings College, London, and Cranfield University, there have been no peer-reviewed recorded cases of neurological harm in humans following TCP exposure. He points to an unpublished report from the Medical Toxicology Unit at Guy's Hospital in 2001 which looked at all exposures dating back to 1943 that showed that all documented exposures are to high concentrations greatly in excess of the amount present in jet oil.
In a 2006 article in Aviation Week, Dr. Simon Bennett[Notes 1] found that media coverage of contaminated cabin air has been sensationalized, with distortions of facts. He cited headlines such as "You are being gassed when you travel by air," and "Death in the Air" and a sub-title of "Every day, planes flying in and out of London City Airport are slowly killing us." Dr. Bennett noted that the article with the latter subtitle stated in its body that the Department of the Environment, Transport and the Regions (DETR) found that oil seal failures occur only once in every 22,000 flights. Similarly, the Sunday Sun in an article entitled "Flight Fumes Warning", cited the industry pressure group AOPIS in saying that passengers jetting off to their holidays were unknowingly exposed to deadly chemicals, and that brain damage could result if they breathed the toxic fumes. However the Sun too admitted that the UK Civil Aviation Authority found that leakage into aircraft cabins is a very rare event that occurs only if there's a fault with an aircraft.
He found that when Sarah Mackenzie Ross submitted the results in 2006 of a clinical audit of the "cognitive functioning of aircrew exposed to contaminated air" to the UK government's Committee on Toxicity of Chemicals in Food, Consumer Products and the Environment (COT), some media used it to write articles that were sensational and misleading.
The Dagbladet.no, a Scandinavian news-based Internet site, wrote that the Ross report "... adds weight to the hypothesis that compounds resembling nerve gas in cabin and flight deck air have caused irreparable neurological damage to aircrew." That, despite the fact that:
- The report was a "clinical audit of aircrew seen for clinical purposes," and was not a valid research study.
- The "'aircrew seen for clinical purposes' were in fact a self-selecting sample of pilots." Meaning that they all came from a group that already believed they had been damaged by contaminated air.
- That self-selected sample group "was not compared to a control group."
- Ross herself said "The conclusions that can be drawn from these findings have limitations."
- She further stated: "The author ... makes no attempt to ascribe causality."
- The report's conclusions were ambiguous: "There was no evidence of ... intellectual decline, language or perceptual deficits .... Indeed pilots were intact on the vast majority of tests. However, there was evidence of under- functioning on tests associated with psychomotor speed, executive functioning and attention ...."
- And finally, "[T]he evidence available to us in this audit does not enable us to draw firm conclusions regarding a causal link with exposure to contaminated air."
The most prominent feature of Dagbladet.no's reporting was its sensationalism. One article used the banner headline: "You are being gassed when you travel by air." That implied that cabin air is contaminated on a routine basis, but, that is not true. In another article, the Dagbladet.no contradicted itself: "When asked by Dagbladet.no for information, the Norwegian Civil Aviation Authority's analysis section ... revealed 13 mysterious incidents which may be connected with contaminated cabin air in aircraft [between 2001 and 2005]." Dr. Bennett asked, "...how a report that was careful not to ascribe causality could be seen to support the hypothesis that organophosphates in flight-deck and cabin bleed air cause neurological damage among aircrew?"
The Times also reported on Dr. Bennett's research into flight crew fatigue and stress. Dr. Bennett commented on that article: "Despite its positioning as a 'quality' newspaper, The Times produced a determinedly skewed account of the research. Important facts—like the limitations of the research methodology (the research paper was based on interviews with just 11 pilots)—were not mentioned by The Times."
Several documentary films have been made on the Aerotoxic Syndrome issue including: Contaminated Air - An Ongoing Health and Safety Issue (2003), Welcome Aboard Toxic Airlines (2007), Angel Without Wings (2011) and Broken Wings (2011). Two feature films are also in the making entitled A Dark Reflection and Shadows From The Sky.
The legal precedent that inhaling oil fumes is harmful was set in the High Court of Australia on the 5 May 2009, in the case Joanne Turner v. Eastwest Airlines. The Australian courts found in favour of Ms. Joanne Turner in her case for compensation against her former employers for injuries resulting from exposure to heated jet engine oils. Ms Turner a former flight attendant with Australia’s Ansett and Eastwest Airlines, was exposed to smoke and fumes resulting from a failed oil seal on a BAe 146 flight between Sydney and Brisbane on 4 March 1992, whilst 5 months pregnant. The court found that Ms Turner was exposed to oil fumes and smoke generated from engine oil that had leaked into a component of the aircraft air supply system called the Auxiliary Power Unit (APU - engine). The failure of the APU oil seal was found to be foreseeable, as was the risk that smoke from the leaking oil would enter the aircraft cabin. The judge found that: “The plaintiff was exposed to pyrolysed Mobil Jet Oil II on 4 March 1992” and “that pyrolysed effects of Mobil Jet Oil II are harmful to the lungs.” The defendant appealed the decision to the New South Wales Court of Appeal and then the High Court of Australia, however subsequently lost both appeals on 1 April 2010 and 3 September 2010 respectively.
In 2011, a former flight attendant is believed to be the first person in the U.S. to settle a lawsuit against the Boeing Co. over what she claimed was faulty aircraft design that allowed toxic fumes to reach the cabin, triggering tremors, memory loss and severe headaches.
The amount and other details of the settlement between former American Airlines worker Terry Williams, a 42-year-old mother of two, and Boeing were not made public as a condition of the agreement.
- Dr. Bennett is director of the Scarman Centre's distance-learning MSc in Risk, Crisis and Disaster Management, with a PhD in sociology from Brunel University, London.
- Nicolas Mateesco Matte (2002). "Aerotoxic Syndrome". Annales de Droit Aérien et Spatial (McGill University. Institute of Air and Space Law) 27: 86–87.
- Hale MA, Al-Seffar JA (September 2009). "Preliminary report on aerotoxic syndrome (AS) and the need for diagnostic neurophysiological tests". Am J Electroneurodiagnostic Technol 49 (3): 260–79. PMID 19891417.
- Select Committee on Science and Technology (2000). Science and Technology - Fifth Report (Report). House of Lords. http://www.publications.parliament.uk/pa/ld199900/ldselect/ldsctech/121/12107.htm. Retrieved 2010-07-05.
- Lord Alec Broers Broers, Air Travel and Health: An Update, Report with Evidence, 1st Report of Session 2007-08, The Stationery Office, Great Britain: Parliament: House of Lords: Science and Technology Committee, ISBN 0-10-401178-5
- David J. Harrington and Justin M. Schmidt (2010-01-01). "Toxic Cabin Air Litigation Continues to Recirculate Through the Courts". The Air & Space Lawyer, Volume 23, Number 2, 2010. Retrieved 2011-10-30.
- National Research Council (U.S.), Committee on Air Quality in Passenger Cabins of Commercial Aircraft (2002). The Airliner Cabin Environment and the Health of Passengers and Crew. National Academies Press. p. 5. ISBN 0-309-08289-7.
- Learmont Flight International, 6 May 2008.
- Helen Muir (2007-11-21). "Cabin Air Sampling Study Functionality Test". Cranfield University via Department for Transport. Retrieved 2010-05-13.
- "Air Safety and Cabin Air Quality in the BAe 146 Aircraft: Report by the Senate Rural and Regional Affairs and Transport References Committee editor-first = Parliament of the Commonwealth of Australia", Commonwealth of Australia, 2000, ISBN 0-642-71093-7, retrieved 2012-05-09
- Air Accidents Investigation Branch Report on the incident to BAe 146, G-JEAK during the descent into Birmingham Airport on 5 November 2000, p.1.
- Air Accidents Investigation Branch Report on the incident to BAe 146, G-JEAK during the descent into Birmingham Airport on 5 November 2000, pp. 3– 4.
- Air Accidents Investigation Branch Report on the incident to BAe 146, G-JEAK during the descent into Birmingham Airport on 5 November 2000, p.56.
- Air Accidents Investigation Branch Report on the incident to BAe 146, G-JEAK during the descent into Birmingham Airport on 5 November 2000,p.31.
- Geoffrey Thomas (January/February 2010). "Clearing the Air". Australian Aviation. Retrieved 2010-05-13.
- Balouet, Winder & Hoffman (October 1999). Aviation and Exposure to Toxic Chemicals.
- [www.parliament.uk/briefing-papers/SN05114.pdf Cabin Air Quality], House of Commons Library, 2009
- "You are being gassed when you travel by air" - Dagbladet
- "Contaminated air questions persist" - Australasian Business Intelligence
- "AOPIS - Air Travel and Health Follow-Up Inquiry: Call for Evidence"
- United States National Research Council (1986). The Airliner Cabin Environment: Air Quality and safety. National Academic Press. ISBN 0-309-03690-9.
- Professor Michael Bagshaw (2008-11-29). "The "Aerotoxic Syndrome"". European Society of Aerospace Medicine.
- Dr. Simon A. Bennett (2006-08-26). "Through a Glass Darkly". Air Safety Week. Retrieved 2010-04-30.
- Victoria Gill (2006-09-27). "Defra Leaves Organophosphate Study Hanging in the Balance". Royal Society of Chemistry.
- Jim Gold (2011-10-06). "Boeing suit settlement stirs jetliner air safety debate". MSNBC. Retrieved 2011-10-30.
- Martin B. Hocking, Diana Hocking (2005). Air Quality in Airplane Cabins and Similar Enclosed Spaces. Springer Science & Business. ISBN 3-540-25019-0.