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UK Civil Aviation Regulations

These are published by the CAA on our UK Regulations pages. EU Regulations and EASA Access Guides published by EASA no longer apply in the UK. Our website and publications are being reviewed to update all references. Any references to EU law and EASA Access guides should be disregarded and where applicable the equivalent UK versions referred to instead.

Doctors and other health professionals may see patients who report symptoms following a ‘fume’ event – an unusual odour, mist or smoke – on an aircraft. The pattern of symptoms reported is quite variable and health professionals have asked for guidance on how best to manage such patients.

The Care Pathway has been developed by an independent working group including experts in toxicology, epidemiology, aviation medicine and primary care, in order to provide advice to health professionals in managing such patients. The working group has also developed an information sheet for patients.

NHS Care Pathway – patients exposed to fumes onboard commercial aircraft

D Wood, P Durgan, N Dowdall, D Coggon, R Hunter, T Stevenson, M Hoghton


Crew or passengers who experience symptoms during or following exposure to a fume incident, or symptoms which they think may have been caused by exposure to contaminants in aircraft cabin air, may seek advice from their GP, hospital A & E Dept, occupational health service or Aeromedical Examiner. These doctors may be uncertain how such patients should be assessed or what investigations might be required.

It is important to consider the possibility of underlying disease that is unrelated to exposure to contaminated cabin air, since the symptoms described are generally non-specific and can occur in a range of conditions. People with symptoms should have the same investigations and, if necessary, specialist referral as would be the case for someone with the same symptoms but who had not been exposed to contaminated cabin air.

This care pathway has been developed by the working group to assist doctors in managing such cases.


The cabin air supply on most large commercial aircraft is provided using engine bleed air systems. Fume events – abnormal odours, smoke, haze or fumes in the cabin – may arise from various internal or external sources, and some are due to contamination of the bleed air supply, for example as a result of a failure of an oil seal in the engine. In recent years concerns have been expressed about possible adverse health effects of exposure to contaminants in cabin air.

There is strong evidence that some people experience acute symptoms as a consequence of fume events. Some of the chemical contaminants that are present during such events are irritant, and may cause itching or soreness of the eyes, nasal discharge, sore throat or coughing. In other cases, there may be a psychologically mediated nocebo response (see note) triggered by awareness of irritation or an odour. From the research that has been done to date on the chemicals that may be present in contaminated air, the concentrations at which they are present, and the reported patterns of symptoms in affected individuals, non-irritant toxic mechanisms for the acute health effects seem unlikely.

In addition to the occurrence of acute health effects, a small number of people have attributed longer term illness to one or more contamination incidents or to repeated exposure to lower levels of contamination. However, it is currently unclear whether any form of long-term illness occurs to excess in people with such exposures, and if so, whether it arises through toxic or nocebo mechanisms. From what is currently known about the concentrations of potentially toxic chemicals in contaminated air, long-term toxic effects would not be expected, but this remains an area of scientific uncertainty. (see Further reading 1,2)

Nocebo effect Note: Illness, often with physical symptoms and signs, which is triggered through psychological processes in response to a perceived harmful exposure. The phenomenon is analogous to a placebo effect in which symptoms improve in response to a perceived beneficial exposure.

Author affiliations

  1. Dr David Wood, Consultant Physician and Clinical Toxicologist, Guys’ & St Thomas’ NHS Foundation Trust and King's Health Partners and Reader in Clinical Toxicology, King's College London, UK
  2. Professor Paul Dargan, Professor of Clinical Toxicology, King’s College London and Consultant Physician and Clinical Toxicologist, Guys’ & St Thomas’ NHS Foundation Trust and King's Health Partners, London, UK
  3. Dr Nigel Dowdall, Head of Aviation Health Unit, Civil Aviation Authority, Gatwick, UK
  4. Professor David Coggon, Emeritus Professor of Occupational and Environmental Medicine, University of Southampton, Southampton, UK
  5. Dr Rob Hunter, Head of Flight Safety, British Airline Pilots Association, Hounslow, UK
  6. Dr Tim Stevenson, Company Medical Adviser, easyJet Airline Company Ltd, Luton, UK
  7. Dr Matthew Hoghton, Medical Director CIRC, RCGP