Aerotoxic syndrome

Aerotoxic syndrome is the name for the long-term ill-health effects that the affected person attributes to breathing contaminated cabin air in an aircraft. The term was introduced on 20th October 1999 by Harry Hoffman, Chris Winder and Christophe Balouet.

The air in a jet or turboprop aircraft cabin is supplied by bleed air from the aircraft’s engines, and some aircrew and passengers say that they have been made ill by toxins in engine oil that can enter the air supply.

Contaminated Bleed air

Jet engines require a complex synthetic oil formulation for lubrication. The oil contains many toxic ingredients such as tricresyl phosphate (TCP), an organophosphate. Seals keep the oil and air separate. The seals used are “wet seals” which means that even with a properly functioning system, there is always a small amount of seepage of oil. Depending on the location of the seal, some of the oil from the compressor stage of the engine will enter the air supply, and in turn some of this will enter the aircraft cabin. If a seal starts to wear or ultimately fail, a larger quantity of oil will be released and may be detected by odour or in more serious cases as smoke in the cabin. This is known as a “fume event”. Although most jet aircraft cabin have filters for the recirculated cabin air, the bleed air supply comes in unfiltered.

Health effects

Not all individuals are affected, and health may become affected after just one fume event or may develop gradually following years of repeated low-level exposures. Symptoms may be delayed, so may not manifest themselves for a few days or even weeks after a fume event.

The 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. Chronic fatigue syndrome (CFS) and Multiple chemical sensitivity (MCS) are also commonly reported by sufferers. 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.

Research

Ongoing research commissioned by the UK government's Department for Transport (DfT) has not managed to conclude a link to long term health. The campaigning groups GCAQE and the Aerotoxic Association contest that these agencies are covering up the issue and trying “not to find a problem”.

According to a report by Prof Michael Bagshaw, 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 which showed that all documented exposures are to high concentrations greatly in excess of the amount present in jet oil. He also noted that studies in Canada and the USA were unable to detect TCP in the cabin during flight. Prof Bagshaw notes that the symptoms are "largely the same as those reported by participants in all phase I drug trials", and are similar to the symptoms experienced by patients suffering from chronic fatigue syndrome, gulf war syndrome, Lyme disease, chronic stress and chronic hyperventilation.

BALPA, the UK's largest pilot union produced a report in 2005 detailing the proceedings of the Air Safety and Cabin Air Quality conference. The 320 page report contains much research supporting a link between contaminated cabin air and health.

See also

• Aerotoxic Association
• GCAQE

External links

• Interests and the shaping of an occupational health and safety controversy: the BAe 146 case, Nickolas Vakas, University of Wollongong, 2007
• Ill health Following Exposure to Contaminated Aircraft Air: Psychosomatic Disorder or Neurological Injury?, S Mackenzie Ross, A Harper, J Burdon, 2006