Aerotoxic syndrome is a term describing 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 and other chemicals.[1] The documentary film Welcome Aboard Toxic Airlines suggests the term was first suggested in 1999 by members of an electronic global ‘egroup’ called Aerotox. Members of this group, included Dr Harry Hoffman, a former US Navy Flight Surgeon, Professor Chris Winder, a toxicologist at UNSW in Sydney and Dr Jean Christophe Balouet a French Environmental forensics expert.
With the exception of the new Boeing 787[2] and the retired Concorde, the air in a jet or turboprop aircraft cabin is typically supplied by bleed air from the aircraft’s engines. Several Pilot and Flight attendant Unions have claimed that aircrew and passengers have been made ill by toxins in engine oil that can enter the air supply.[3]
As of 2009 this syndrome is not officially recognized in aviation medicine.[4] The term was used by a year long Australian Senate Investigation that concluded in 2000, that inhaling heated engine oils fumes was a risk to health and flight safety.
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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.[5] 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.[5]
A service information leaflet from the UK-based Committee on Toxicology (COT)[6] provided a list of possible sources of poor quality cabin air. Some of the items on that list include:
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.[7] 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”.[8] Although most jet aircraft cabins have filters for the recirculated cabin air, the bleed air supply is not filtered.[7]
In a flight safety bulletin to all operators, dated January 5, 2001, BAE Systems included the following information:
During the last year there have been several reports of the appearance of smoke or fumes originating from the air conditioning system. Investigation has identified most of the root causes of these incidents:
There are many technical reasons why aircraft have smells or minor appearances of smoke from air conditioning systems including, for example, inappropriate temperature settings relative to ambient conditions or inadvertent ingestion of hydraulic fluid or de-icing fluids. Recently the main focus of attention has been on the possibility of oil from either the main power plant or the APU contaminating the cabin air via these systems. The air supply is protected from contamination by seals, which achieve maximum efficiency during steady state operation. However, they may be less efficient during transients (engine acceleration or deceleration) or whilst the engine is still achieving an optimum operating temperature. Improvements in seal design continue to improve efficiency, and when available, modifications are provided for the engines and APU.[9]
- Technical (the majority), rectification of which prevented further occurrences.
- Self-inflicted, such as ingestion of de-icing fluid, through the APU intake and into the cabin air supply.
- Perceived, due to condensation in the air supply. This may occur if an inappropriate cabin temperature is selected, causing the air conditioning system to over cool the cabin air.
According to Dr. S. Michaelis, crews have been impaired or incapacitated in flight on a number of occasions, following exposure to fumes during flight.[10]
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,[11] with both becoming nauseous, and the pilot experiencing double vision and having difficulty judging height. Despite this, he managed to land the aircraft safely.[12] "The first officer and commander were taken to hospital and examined, but no abnormalities were found."[11] 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."[13]
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."[14][15]
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.[16] Chronic fatigue syndrome (CFS) and Multiple chemical sensitivity (MCS) are also commonly reported by sufferers. 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.[17]
Aviation Organophosphate Information Site (AOPIS) is a non-profit group set up by airline crews in Australia in 2001.[18][19] 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.[20]
The Global Cabin Air Quality Executive (GCAQE) is a global coalition of health and safety advocates committed to raising awareness and finding solutions to poor air quality in aircraft[21] and was established in 2006 by a number of unions such as the Independent Pilots Association (UK), Unite the Union, Australian and International Pilots Association, Association of Flight Attendants, Canadian Union of Public Employees and others.
Lastly, the Aerotoxic Association was set up on 18 June 2007. The association is run by a group of airline pilots who believe they were made ill by contaminated cabin air.
In 1986, the United States Congress commissioned a report by the National Research Council (NRC) into cabin air quality.[5] 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.[22]
However little research took place into cabin air quality in the following 15 years, despite ongoing concerns raised by passengers and crew. In 2000, Congress responded by once again directing the NRC to conduct an independent study into cabin air quality, and to make recommendations for improvements.
Ongoing research commissioned by the UK government's Department for Transport (DfT) has not managed to conclude a 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,"[23] the UK Parliament's Select Committee on Science and Technology, concluded:
According to a report by former British Airways Head Doctor, Prof Michael Bagshaw, there have been no peer-reviewed recorded cases of neurological harm in humans following TCP exposure.[25] 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.[25]
According to Dr. S. Michaelis, TCP has been detected in aircraft cabins during numerous air and swab sampling tests.[10]
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.[26] 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.[26] 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.[26]
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),[27] some media used it to write articles that were sensational and misleading.[26]
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."[26] That, despite the fact that:
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."[26] That implied that cabin air is contaminated on a routine basis, but, that is not true.[26] 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?"[26]
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."[26]
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]. A feature film is also in the making entitled "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.[28]
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 Wednesday 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.[29]