Select Committee on Science and Technology First Report

CHAPTER 4: Areas for action raised in the current inquiry

The Cabin Environment

4.1.  We mentioned above the CAA-funded research Anthropometric Study to Update Minimum Aircraft Seating Standards published in 2001. The study recommended that the regulatory minimum distance between seats should be increased to a minimum of 28.2 inches. The report goes on to say that "the ideal recommendation would be to increase … [the regulatory minimum distance between seats] to at least 29.4 inches" to include the 1st to 99th percentile range of the world population; "and, depending on the outcome of any further work to specify an optimum safe brace position, … [the regulatory minimum distance between seats] would need to increase to at least 35 inches"[34] . We find it astonishing that the CAA has chosen to ignore this piece of research and its recommendations. Dr Ray Johnston told us, that "no airline … operates a 26 inch pitch", which is the minimum regulatory standard, and that "every airline that I have researched has a seat pitch greater or equal to 28 inches" (Q 262). This misses the point, which is that the value of a regulatory minimum lies in large part in the signal that it sends to industry of the kind of standards expected for air travel. Moreover, if no airline has a seat pitch of less than 28 inches there would appear to be no reason why the CAA should not implement the recommendations of its own research, and increase the regulatory minimum to 28.2 inches at minimal cost to the industry. The impending transfer of responsibilities to EASA makes this change all the more important.

4.2.  In our 2000 report we welcomed the prospect of new products, such as "premium economy" seating, which allow passengers to purchase extra leg room in a long-haul flight for a "modest premium" (Q 3)[35]. These "premium economy" or "economy plus" services have been designed for those passengers that require space above a reasonable minimum. However, we heard from Roger Wiltshire, Secretary General of the British Air Transport Association (BATA), that this category of products attracts "the high rate of air passenger duty", along with business and first class. This duty was doubled in February 2007 from £40 to £80 (QQ 3-4). Given that premium economy seating appears to be one way in which airlines are catering for the health requirements of taller passengers, we agree with BATA that premium economy should be taxed at the standard rate of air passenger duty.

4.3.  In the original report we recommended that airlines should review and modify their cabin design considerations to include personal air outlets (PAOs). We are pleased to hear that PAOs are standard equipment on some aircraft, including the new Boeing 787 (p 114) due to come into service in the next few months. However, in other models PAOs are considered optional extras. We reiterate our conclusion in 2000, that PAOs can provide personal refreshment to passengers, thus enhancing the flying experience.

4.4.  With regards to ventilation, we are gratified to hear that "HEPA filtration for recirculated cabin air is standard equipment on all Boeing production aircraft" (p 114) and all Airbus production aircraft (p 101). For older planes there are retrofit solutions. Airbus also told us that "monitoring systems are already in place on the A330 and A340 family or aircraft" which monitor the performance of filters (p 102).

4.5.  We also received evidence on cabin pressure. The maximum permitted altitude within the pressurised aircraft cabin is equivalent to 8,000 feet, and at that altitude, even though the percentage of oxygen in the cabin air remains unchanged at 21 percent, the reduction in pressure means that the oxygen level is equivalent to 15 percent at sea level, which is perfectly adequate for healthy individuals. Dr Dowdall told us that "very few aircraft" actually reach the maximum permitted cabin altitude; however, there is no doubt that changes in pressure and in the availability of oxygen take place (Q 98).

4.6.  There does not appear to be any firm evidence that these changes in altitude have a significant impact upon normal, healthy individuals. Dr Dowdall argued that the "human body is perfectly able to function" (Q 98) on 15 percent oxygen, and the Aerospace Medical Association (AsMA), which has conducted research in this area, confirmed that they "could find no evidence that lowering the cabin altitude would prevent significant adverse health effects on reasonably healthy passengers and cabin crew." However, AsMA concluded by saying that it would "encourage more research to be done into this area" (p 98).

4.7.  At the same time Dr Dowdall accepted that passengers with pre-existing conditions, such as lung disease, might be more vulnerable to in-flight hypoxia, and for such passengers the provision of supplementary oxygen might be required. The ICE project examined a number of environmental conditions including a range of cabin altitudes from ground level to 4,000, 6,000 and 8,000 feet. The population studied included a subset of individuals with cardiac and respiratory disease. We look forward to the publication of this study in the autumn of 2008. In the long term changes in aircraft construction, such as the use of composites already seen in the Boeing 787, could lead to aircraft being pressurised to a lower level. However, in the meantime, given the dearth of information on the effects of cabin pressure on passengers with existing medical conditions, we agree with AsMA that more research is needed. This research should focus on those with pre-existing conditions that make them vulnerable to hypoxia.

4.8.  We mentioned in Chapter 2 the Control of Noise at Work Regulations 2005. We welcome these regulations that remove the exemption that existed in relation to aircraft. On the other hand, while we understand that noise in the aircraft generally has been and is being researched as part of ICE, FACE and HEACE, we have not heard of any research being conducted on noise in the cockpit. The issue remains relevant. We heard from BALPA that "noise induced hearing loss is both permanent and prevalent in the industry yet protection is easily affordable". British Airways has conducted investigations in the issue and in fact introduced noise-attenuating headsets as a result (p 89). The Government assured us that the Aviation Occupational Health and Safety Working Group, chaired by the CAA, was looking into this issue (p 89).


4.9.  We recommend that the CAA implement the recommendations of its own research into aircraft seating standards, and increase the regulatory minimum distance between seats to at least 28.2 inches. The Government should also make the strongest possible representations to EASA on this subject when they take over responsibility on this issue.

4.10.  We recommend that the Government urgently review the level of air passenger duty levied on "premium economy" seating. We further recommend that they explore ways in which the airlines can be encouraged to offer extra space to passengers for a modest premium.

4.11.  We welcome the fact that the Aviation Occupational Health and Safety Working Group, chaired by the CAA, is looking into noise-induced hearing loss. However, pending the outcome of this work, we recommend that the CAA work with airlines to review the availability of personal protection equipment so that pilots will be better able to protect their hearing.

Deep Vein Thrombosis

4.12.  DVT is a condition in which a small blood clot forms in the deep veins of the legs. Symptoms of this condition include swelling of the leg possibly accompanied by pain and tenderness. In itself DVT is not dangerous but when a blood clot, or thrombus, breaks away from the walls of the vein, blood flow carries it away and it may block a distant blood vessel causing a venous thromboembolism (VTE). A pulmonary embolism occurs when a blood vessel in the lungs is blocked, which can cause breathing difficulties and chest pains, and in extreme cases respiratory failure and death.

4.13.  At the time of our original inquiry air travel-related DVT was in the headlines. However, little was known as to the real link between air travel and DVT. The WRIGHT Project has filled some of the gaps in reaching some important conclusions as detailed above. It provides reassurance that for individuals without risk factors for thrombosis the increased risk of DVT when flying is no higher than that when travelling by other means, for example train or bus. However there is still much that is not known, including what cabin environmental factors compound DVT probability in passengers with existing risk factors. We reiterate that the Government should support Phase II of the WRIGHT project to address these issues.

4.14.  Public awareness of travel-related DVT has continued to increase since our original report. Media reports have had an influence but also information provided by airlines has improved since 2000. We are concerned, however, at the lack of information targeted not just at the general public, but at those passengers with existing medical conditions, who are thus more susceptible to DVT according to the WRIGHT study. We address this issue in more detail below under the heading "Information and Education".

4.15.  The report on the Extent of Aspirin Use for the Prophylaxis of DVT on Long Haul Flights also revealed some worrying statistics, including reports that 20 percent of passengers of long-haul aircraft passengers questioned had taken or planned to take aspirin before, during or after their long-haul flight. Although this was a small study, we are concerned at the number of people who were thinking of taking aspirin before, during or after a long haul flight. Passenger information on the benefits of taking aspirin for the prophylaxis of DVT seems contradictory. Websites such as promote the use of aspirin before a flight stating "the day before the flight, take a low does of aspirin (100-150 mg), during the flight, and for three days following the flight"[36]. On the other hand, the National Travel Health Network and Centre (NaTHNaC) advises passengers on their website "aspirin should not be used for the prevention of DVT in travellers"[37]. We also heard from Roger Wiltshire that the information that airlines provide to passengers "is being reviewed" to "ensure that we are not encouraging people to take aspirin" (Q 11).

4.16.  Dr William Toff, Professor of Cardiology at the University of Leicester and member of the WRIGHT Project Scientific Executive Committee, told us that "for the average traveller the use of aspirin is a relatively ineffective intervention" in the prevention of DVT (Q 128). While it may have an effect in reducing the risk of arterial thrombosis it has no effect on venous thrombosis. Indeed in some cases the use of aspirin may be counter-productive. Dr Toff went on to say that "you have to treat a lot of people to prevent one thrombosis and the estimate would be something in the region of treating 24,000 people to prevent one thrombosis. On the other hand, the number that you need to treat for harm from aspirin is in the region of one in 17,000" (Q 128). In other words, on the balance of probabilities, and for the population as a whole, taking aspirin as prophylaxis is more likely to do harm than good.


4.17.  We recommend that the Government and the AHU work together with airlines and others in providing consistent travel advice to passengers on the risks associated with self-medicating with the intention of preventing DVT.

Infectious Diseases

4.18.  The general perception that infectious diseases can be transmitted via the cabin air environment has not gone away despite reassurances given by our original report and others such as the WHO. The risk of cross-infection in the aircraft cabin environment is the same as any enclosed space such as an office building. Passengers are at equal or greater risk of transmission of infection in other travel-related situations, such as public transport or airport lounges.

4.19.  Although currently HEPA filters are not mandatory the majority of modern commercial aircraft are fitted with HEPA filters. We heard from Mr Wiltshire that "filtration systems now are all up to the highest HEPA filter standards" (Q 5). In our original inquiry we reported concerns about the lack of regulation with regards to maintenance of these filters. We raised this issue at our seminar and we were told that the CAA had responsibility for checking that the filters were maintained regularly as part of the general maintenance schedule and that regular spot checks were carried out.

4.20.  However, if the spread of infection on board a flight is not a serious concern, the role of air travel more broadly as a vector in the spread of disease is becoming increasingly clear. Some 40 new pathogens have been discovered since 1967, which, along with familiar pathogens such as influenza and tuberculosis, pose a threat to global public health security. One of these new pathogens, SARS, was first identified in southern China in November 2002 and the WHO recognised it as a global threat in March 2003. It has been described as the "first severe and readily transmissible new disease to emerge in the twenty-first century"[38]. Within a short time SARS affected approximately 8,000 people in 29 countries constituting a major international public health emergency. Despite the clear role of international travel in the spread of SARS during the 2003 outbreak, only one case of in-flight transmission has been confirmed.

4.21.  Pandemic influenza potentially poses a much greater threat than SARS. Such pandemics occur on average around three times a century, when a strain of avian influenza acquires the ability to infect and pass efficiently between humans[39]. Since 1997, when the H5N1 strain of the influenza virus was isolated in humans, it has caused at least 308 deaths. All the victims appear to have contracted the disease through close contact with infected animals, and there have been no confirmed cases of human-to-human transmission. However, should the virus mutate so as to acquire the ability to pass readily between humans, the consequences could be grave. The H1N1 pandemic of 1918-19 is estimated to have killed between 20 and 50 million people.

4.22.  Airlines carry two billion passengers each year, potentially enabling disease to travel from one country to another in a matter of hours. This raises the question of what measures could be introduced to slow the spread of disease. One approach would be to seek to isolate the source of an outbreak by stopping all travel in or out of the affected region. This might only delay the spread of a pandemic by a few weeks, but the time gained might be crucial in allowing for the development of a vaccine. At the same time the cost to the global economy of a suspension of air travel to, say, south-east Asia, would be enormous.

4.23.  An alternative approach, introduced at the time of the SARS epidemic, is airport screening to "filter out" infected passengers. However, when we asked Professor Bagshaw his opinion on screening procedures at airports he said that that they were not robust enough. He added, "putting a thermometer in somebody's ear is not very helpful" in detecting individuals in the early stages of influenza (Q 163). This bears out our conclusion in our recent report on Pandemic Influenza that airport screening procedures were unlikely to be effective in preventing a global influenza pandemic.

4.24.  We received very little evidence of the extent and level of contingency planning for a possible pandemic, as it affects the airline industry. The airlines reassured us that they had contingency plans in preparedness for a pandemic and that these plans were regularly tested (QQ 60-61). They told us that international organisations such as the WHO, the International Civil Aviation Organisation (ICAO) and the International Air Transport Association (IATA) "have developed protocols and guidance for airlines and for airports" (Q 60). Airlines also work with the DfT, the DH and the AHU in pandemic planning. However, in the absence of details of such plans we are unable to reach any conclusion as to their likely effectiveness. We therefore confine ourselves to two basic recommendations to the airlines and the Government detailed at the end of this section.

4.25.  The risk of disease transmission within the aircraft cabin environment is greater when sitting within two rows of an infectious passenger for a flight of more than eight hours (Q 57). Indeed, evidence suggests that disease is more likely to be spread by skin contact (whether direct or indirect, via contaminated surfaces in toilet facilities or elsewhere) than via ventilation systems—though advice from WHO shows that viruses such as that which causes SARS lose infectivity after exposure to commonly used disinfectants[40]. However, transmission becomes widespread within all sections of the aircraft cabin when the ventilation system is non-operational. Indeed the WHO recommend in their Tuberculosis and Air Travel Guidelines that "in case of ground delays of more than 30 minutes, adequate cabin ventilation must be ensured"[41].

4.26.  We also note that on 15 June 2007 the International Health Regulations (IHR) 2005 came into force globally. These Regulations aim "to prevent, protect against, control and provide a public health response to, the international spread of disease[42]". The Government are currently consulting on changes that might be made to the Public Health (Control of Disease) Act 1984 in the light of the IHR 2005. The Regulations highlight seven areas of work:

  • Fostering global partnerships;
  • Strengthen national disease surveillance, prevention, control and response systems;
  • Strengthen public health security in travel and transport;
  • Strengthen WHO global alert and response systems;
  • Strengthen the management of specific risks, such as influenza, SARS and yellow fever;
  • Sustain rights, obligations and procedures; and
  • Conduct studies and monitor progress on the implementation of the IHR 2005 at national and international level.

4.27.  The WHO in their World Health Report 2007[43] recommend among other things that all countries implement fully the IHR 2005. We agree: the Government must take forward their consultation as a matter of urgency.


4.28.  We recommend that the Government and the airlines advise passengers on the proven benefits of good hand hygiene in the reduction of disease transmission and in particular that passenger clean their hands before eating on board an aircraft. In the event of a disease outbreak that could lead to a pandemic, we recommend that as part of their contingency plans airlines flying from affected regions should provide bactericidal wipes and alcohol gels to limit the spread of disease in-flight.

4.29.  We recommend that the Government and the regulators limit the amount of time that passengers can remain in an aircraft when the ventilation systems are non-operational to 30 minutes.

Air Crew Occupational Health

4.30.  The current version of CAP 371 was published by the CAA in January 2004[44]. These regulations "set a work pattern for flight crew and cabin crew designed to prevent the onset of fatigue, and yet allow an operator to pursue legitimate business interests". The spirit of CAP 371 is clear:

"The prime objective of a flight time limitations scheme is to ensure that crew members are adequately rested at the beginning of each flying duty period, and whilst flying be sufficiently free from fatigue so that they can operate to a satisfactory level of efficiency and safety in all normal and abnormal situations. Aircraft operators are expected to appreciate the relationship between the frequency and pattern of scheduled flying duty periods and rest periods and time off, and give due consideration to the cumulative effects of working long hours interspersed with minimum rest."

4.31.  However, both the pilots' unions, BALPA and the IPA, highlighted fatigue as a new health concern which had emerged since 2000. The problem as described by them was that new technology allows airlines to set work schedules far more efficiently, so that pilots are regularly made to work to the maximum flying time permitted by CAP 371—observing the letter of the regulations, but not the spirit.

4.32.  More specifically, BALPA's Occupational Health and Safety Group told us in their written evidence that "fatigue is cumulative, but our rostering systems assume that the tiredness counter in each pilot is reset to zero on the first day of each month and take no account of the previous month's experiences. This is a potential flight safety hazard which needs a fresh approach" (p 118).

4.33.  Other issues were enumerated as compounding the problems, such as very early flights on the first day of a working period and late flights back on the last day of a working period, thus eroding pilots' rest periods; returning to a different airport than the pilots' base; the provision by some airlines of self-drive cars for pilots who arrive at a different airport from their normal base; and staff car parking being located far away from base. All these eat into rest time.

4.34.  CAP 371 goes on to say "an operator must submit for approval to the CAA a proposed scheme for the regulation of flight and duty times and provision of minimum rest periods". It follows that the CAA must approve the rostering patterns of all airlines registered in the United Kingdom. At the same time it is worth noting that there are airlines not registered in the United Kingdom that employ British pilots and have bases in airports in the United Kingdom. Such airlines are not bound by CAA regulations.

4.35.  With the expansion of low cost airlines the air travel business has become increasingly competitive. Airlines will naturally seek to maximise productivity from their aircrew. However, this must not be at the expense of safety. When Captain Tim Bamber of BALPA was asked "would you be as clear as saying you have reason to believe some airlines are putting passengers and/or crew at risk by their practices?", he replied "without hesitation I would say that; yes" (Q 191).

4.36.  Jim Fitzpatrick MP told us "the Department for Transport and the CAA are keen to discuss this issue with BALPA. The Secretary of State wrote to BALPA on 5 June 2007 inviting them to come in to discuss their survey with officials, so this is a report that we are indeed taking seriously" (Q 305). He continued, "If safety were to be compromised as a result of fatigue, obviously we would need to address that seriously … The Aviation Health Working Group will be prepared to look at it but that will be a matter pending the outcome of the discussions we will have with them shortly" (Q 307). We will follow with interest the outcome of these conversations.


4.37.  We are reluctant to recommend the modification of CAP 371 until more evidence is presented. We recommend, however, that the Government together with the CAA (including the AHU), the unions and airlines work together to find a way of ensuring that pilots have appropriate rest periods and to monitor fatigue complaints by pilots. We also recommend that the CAA, as the body responsible for the health and safety of air crew while on board an aircraft, commission a study into the long-term effects of fatigue in air crew.

Contaminated Air Events

4.38.  Most aircraft currently in service or in production have ventilation systems that re-circulate cabin air. In aircraft with re-circulated air systems air from the first stage of the engines (bleed air) is cooled and conditioned (but not filtered) in the air conditioning packs in order to achieve an air pressure and temperature closer to that experienced on the earth's surface. This air is then mixed with cabin re-circulated air (filtered) in a mixing manifold before being blown to the cabin where the air will circulate for two to four minutes before being expelled from the aircraft. In most cases air supplied to the cockpit is extracted from only one of the two air conditioning packs.

4.39.  A contaminated air event (or fume event) takes place when, due to an oil seal failure, engine oil or hydraulic fluid enters the cabin via bleed air from the engines. These oils or fluids are subject to extreme temperatures in the engines which can cause thermal decomposition (pyrolysis) into a range of substances such as volatile organic compounds (VOCs), low molecular weight organic acids, esters, ketones and tri-cresyl phosphate isomers.

4.40.  In our 2000 report we concluded that, on the evidence received, the concerns about significant risk to the health of airline passengers and crew arising from contaminated air were not substantiated[45]. However, public and media interest of such reported incidents has significantly increased in recent years, supported by the emergence of a strong and co-ordinated campaign by a range of organisations dedicated to raising the profile of this issue. Some 80 percent of the submissions received in the course of this inquiry mention contaminated air events as a health concern. Submissions also included personal accounts from pilots who claimed they had suffered ill health, and consequently the loss of their licence, following one or more contaminated air events.

4.41.  At the meeting of the AHWG on 27 October 2004 BALPA raised concerns about contaminated air events and the long term health of flight crew and cabin crew. The union requested among other things, an independent study to understand the scale of the problem and a medical protocol for dealing with crews following a contaminated air event[46]. In response to this, in late 2005, the DH-funded Toxicology Group at Imperial College asked the independent Committee on Toxicity of Chemicals in Food Consumer Products and the Environment (COT) to conduct a scientific review of the evidence submitted by BALPA and to provide the DfT with advice on research needed on this subject. The COT has met a number of times with interested parties. Not only have they reviewed the data submitted by BALPA but they have requested additional information from various sources such as the CAA and experts.

4.42.  In March 2006 the COT asked Dr Sarah Mackenzie Ross, a Consultant Clinical Neuropsychologist based at University College London, to prepare a report describing the results of assessments she had carried out on 27 pilots who had been referred to her for neuropsychological and adult mental health assessment. She found that all but one of the pilots showed "evidence of cognitive impairment but in very specific areas … they were slower to process information, they had fluctuating attention and they had some difficulties with high-level functions like multi-tasking" (Q 136). She looked for alternative explanations to the symptoms presented but found "we had 18 pilots who were impaired and ill and we could find no explanation for why that was the cause … these people are definitely ill; that is beyond a doubt" (Q 136). The COT arranged for an independent review of Dr Mackenzie Ross's audit by Professor Robin Morris of King's College Hospital. He concluded that the study "cannot suggest a link and equally does not rule out a link" (Q 296).

4.43.  The COT published a statement on 20 September 2007[47]. In its conclusions the COT stated that "it was not possible ... to conclude that there is a causal association between cabin air exposures (either general or following incidents) and ill health in commercial aircraft crew. However, we noted a number of oil/hydraulic fluid smoke/fume contamination incidents where the temporal relationship between reports of exposure and acute health symptoms provided evidence that an association was plausible". The COT also concluded that "there was insufficient evidence … to recommend additional epidemiological research on any acute health effects". However, it considered that "overall the potential for cognitive deficits needed further consideration".

4.44.  Sandra Webber, Chairman of the AHWG, told us that cabin air quality and contaminated air events were in the top three priorities of the Group (QQ 229-230). The AHWG, anticipating what the COT would recommend (Q 180), had "just begun a ground breaking research project, a world first, using experimental technology" (Q 295) into contaminated air events. Tests will involve simulating and analysing a fume event on the ground and then sampling "around 1,000 flights" to analyse the results. Jim Fitzpatrick MP, told us "we are very much at an early stage but we are putting a lot of effort and resource into addressing this problem because we do acknowledge that there is an issue of concern here" (Q 300). We welcome this research. However, we note that if the incidence of contaminated air events is as low as is claimed by the Government (see below) the sampling of 1,000 flights offers only a remote chance of capturing an event, unless the sampling is targeted at types of aircraft more prone to such events. We therefore trust that the sampling of air in-flight will continue until conclusive results are reached.

4.45.  The position adopted by the COT is essentially that the case for any health effects resulting from contaminated air events is unproven, but worthy of further investigation. It is difficult for us to dissent from this judgement, based on the evidence available to us. On the one hand we heard from Dr Nigel Dowdall of British Airways who told us that "I have no evidence to suggest that there is a serious medical problem here" (Q 73). On the other hand claims by pilots, unions, passengers and pressure groups suggest otherwise. The IPA told us that nine of its members have either lost their licences or are under investigation from the CAA due to ill health allegedly caused by contaminated air events. The CAA-funded research mentioned in paragraph 3.6 confirms that contaminated air events can cause acute health effects on air crew. However, opinions differ with regards to long-term health effects.

4.46.  Almost all aspects of this subject are disputed by the different sides. The number of contaminated air events is itself a contentious issue. The CAA claims that all fume events are reported and investigated (QQ 298-99). However the unions cited allegations that airlines discourage pilots from reporting contaminated air events (QQ 214-15). The COT estimates, on the basis of information provided by three airlines, that "engineering-confirmed smoke/fume incidents occur in around 0.05 percent of flights but that the incidence may be higher than this"[48]. Captain Susan Michaelis, a former pilot, who lost her medical certificate in 1999 and has since conducted extensive research into contaminated air incidents, claimed the number to be much higher, and told us that "under reporting of contaminated air events continues with less than 4 percent actually reported" (p 130).

4.47.  The chemicals alleged to cause ill health are also disputed. In our original report tri-cresyl phosphate (TCP), and in particular the isomer tri-ortho-cresyl phosphate (TOCP) were evaluated. The organophosphate TCP is present in some synthetic jet engine oils and can be broken down into three sub-groups: the -meta, -para and -ortho isomers of TCP. The -ortho isomers are broken down into three isomers known as tri-ortho-cresylphosphate or TOCP, mono-ortho-cresylphosphate or MOCP and di-ortho-cresylphosphate or DOCP[49]. The Global Cabin Air Quality Executive claimed that TOCP was in fact the least toxic of the ortho isomers, with DOCP being five times more toxic and MOCP 10 times more toxic than TOCP. However, we have had no confirmation of this one way or another. Dr Mackenzie Ross likened the profile seen in pilots to that seen in farmers exposed to organophosphates in sheep dip. In contrast Dr Nigel Dowdall of British Airways told us that "I believe the organophosphates element of this is something of a red herring" (Q 83).

4.48.  It is clear to us that the evidence base for reaching conclusions on contaminated air events is incomplete, and that more research is needed both to identify the substances produced in a contaminated air event, and to analyse their possible effects on health not just individually but in combination. Dr Mackenzie Ross recommended that research take account of the "potential synergistic effects of the range of different chemicals found in engine oil", adding: "when certain chemicals are combined, even at safe levels, the end product can be more toxic than what would be predicted from the known properties of each chemical that makes up the mixture" (p 26).


4.49.  We recommend that the CAA carries out an awareness campaign aimed at airlines and pilots to highlight the importance of reporting contaminated air events and encourages airlines to follow the spirit as well as the letter of the rules on reporting these events.

4.50.  We recommend that the AHWG-sponsored research to identify the substances produced during a fume event be completed urgently. It should be followed up by an epidemiological study on pilots to ascertain the incidence and prevalence of ill health in air crew and any association there might be with exposure to the chemicals identified in the AHWG-sponsored study, paying particular attention to the synergistic effect of these chemicals.

4.51.  We recommend that the Government works with manufacturers, airlines and the regulator to take effective action in preventing oil and hydraulic fluid leakages into the aircraft cabin.

4.52.  We recommend that a protocol should be made available to health professionals, in particular Authorised Medical Examiners, on how to deal with air crew who suffer contaminated air events. We recommend that airlines, the regulators and the Government work together to improve the support given to pilots claiming to suffer ill health following a contaminated air event.

Fitness to Fly

4.53.  There has been a dramatic growth in air travel in the last twenty years. Aviation currently transports two billion passengers annually[50] and passenger traffic is projected to grow by an average of 4.9 percent per year[51]. Although the great majority of the flying public are healthy or have no reason to believe that they are not, there are also now many more travellers with pre-existing health problems. Figures from Stansted Airport show that from 2000 to 2006 the proportion of passengers over the age of 60 has increased from 11 to 17 percent (Q 270). At the same time passengers with certain medical conditions, in particular heart and lung diseases, may not be fit to fly. Health organisations contraindicate flying to individuals with a number of medical conditions. The list of such medical conditions is fairly standard across the board. The WHO's advice is summarised in Box 3[52].


Advice on contraindications to air travel by the WHO

Travel by air is normally contraindicated in the following cases:

  • Infants less than 7 days old;
  • Women after the 36th week of pregnancy (after 32nd week for multiple pregnancies) and until seven days after delivery;

Those suffering from:

  • angina pectoris or chest pain at rest
  • any serious or acute infectious disease
  • decompression sickness after diving
  • increased intracranial pressure due to haemorrhage, trauma or infection
  • infections of the sinuses or infections of the ear and nose, particularly if the Eustachian tube is blocked
  • recent myocardial infarction and stroke (time period depending on severity of illness and duration of travel)
  • recent surgery or injury where trapped air or gas may be present, especially abdominal trauma and gastrointestinal surgery, cranio-facial and ocular injuries, brain operations, and eye operations involving penetration of the eyeball
  • severe chronic respiratory disease, breathlessness at rest, or unresolved pneumothorax
  • sickle-cell disease
  • psychotic illness, except when fully controlled.
  • The above list is not comprehensive and fitness for travel should be decided on a case-by-case basis.

4.54.  Such lists of medical conditions could usefully differentiate between severe conditions, when flying is completely contraindicated, such as very recent gastrointestinal surgery, and those conditions when there is a level of discretion, with individuals entitled to exercise personal responsibility, in light of medical advice—for instance, an infection of the sinuses.

4.55.  Airlines and tour operators give out health information when requested and their websites generally include guidelines on fitness to fly and medical clearance before flying. We heard from the airlines that they have systems in place to clear passengers for flying when passengers contact them with specific queries. Ground staff are able to contact remote medical assistance operators if a passenger's fitness to fly was in question at check-in or at the gate. However, when tickets are purchased no questions are asked with regards to the passenger's fitness to fly and "much depends on awareness and self declaration of health" (Q 147). The Head of Health Services at British Airways told us that "we have probably gone as far as we realistically can in terms of stopping people flying who should not" (Q 31).

4.56.  Nonetheless existing medical conditions which are not necessarily a problem on the ground may well cause difficulties in flight. A significant proportion of serious in-flight medical emergencies are related to existing medical conditions and in many cases these incidents could have been avoided if there had been awareness by the patient and their doctor of the interplay between their condition and the flight environment. The provision of supplemental oxygen during flight, or the delay of travel until the condition is better stabilised, can only be done if both the patient and doctor are aware of the risks of flying.

4.57.  Professor Bagshaw told us that "the number of in-flight medical incidents has not changed" since our original report (Q 148). British Airways provided us with some statistics: "in the year to 31 March 2007, the airline carried 33 million passengers … over the same period the airline recorded 1,700 in-flight medical incidents for which the crew sought the assistance of the MedLink ground-to-air medical advisory service … and there were 50 flight diversions for medical reasons out of the more than 270,000 services operated by British Airways" (p 3). Thomsonfly told us "the defibrillators are used on average about five times a year on board the aircraft and have even been used on a baggage handler who had a heart attack and also on an air bridge to assist a passenger" (p 146). Automated external defibrillators save lives, even if the number is small, and we are therefore pleased to note that all airlines now carry automated external defibrillators on long-haul flights and some airlines carry them on board all their aircraft.

Information and Education

4.58.  The amount and quality of information available to the public have changed significantly since the publication of our report in 2000. Not only have contents been updated but also the medium used for disseminating information has changed. When we questioned Ministers in oral evidence on the information available to the public they replied with an enumeration of the websites available for public consultation. This stands in direct contrast to our original recommendations, which concerned updating leaflets and posters for doctors' surgeries.

4.59.  As we mentioned in paragraph 1.6, in response to our 2000 report the airlines have greatly improved the in-flight information provided to passengers; most airlines also now recommend that their passengers do a certain amount of exercise while on the aircraft. We warmly welcome this change. We also note that the information generally available to the public, in large part through the medium of the Internet, has been greatly improved since 2000. But this carries a risk. A substantial proportion of the general public, around 38 percent in the United Kingdom[53], do not have Internet access. Among those who have lower than average levels of access to the Internet are the very people who need the most information with regards to existing medical conditions and their general fitness to fly—the elderly. Creative ideas are needed to target such groups. For instance, a leaflet on fitness to fly could be sent to all people applying for a European Health Insurance (EHI) card via the post office. And, despite the advance of technology, it might be that our recommendation back in 2000, to put posters on the wall of GPs surgeries, could be a better way to target such people.

4.60.  With regards to the content of some of the websites mentioned in evidence, we were disappointed to discover that the AHU website is based on a series of links to other departments and organisations. This is not what we would expect of an organisation intended to be the "focal point" for passenger health. Indeed, we have seen no evidence that websites such as the DH or the Health Protection Agency (HPA) provide links to the AHU website. We note the comments from Dr Ray Johnston that one of his aims "is to try and bring this separate information into one area, i.e. the AHU" (Q 276). We come back to our earlier recommendation that the AHU should work with others in raising its profile among the travelling public, airlines and physicians.

4.61.  We would also like to throw in a note of caution with regard to information provided online, which almost inevitably relies heavily on links to other websites. Although disclaimers are common concerning responsibility for the content of other websites, Internet users are not necessarily able to judge the reliability of such content. Publicly funded organisations should therefore make simple initial checks before providing a link to other sources of information, and should conduct regular spot checks subsequently. For example the HPA, which in 2003 took over responsibility for providing travel health advice to the public from the DH, provides a link on its website to the BBC Travel Health section[54], which in turn contains the following statement:

"In general, the air quality in planes isn't as good as the air outside, and air filters aren't always fully effective. This allows bacteria and viruses to spread easily from one person to another, which is why many people come home from their holiday with a cough or cold."

4.62.  This is nonsense. Incorrect information not based on evidence helps perpetuate misconceptions about air travel. We would have preferred to see a link from the HPA and the BBC to authoritative advice provided by the AHU instead.

4.63.  We heard repeatedly throughout this inquiry that if a passenger had any concerns about air travel and health or had any existing medical conditions they should contact their GP for advice before travelling. The question that follows from this is whether GPs are adequately trained in aviation medicine and do they keep abreast of the latest guidelines?

4.64.  According to Professor Bagshaw, "my experience with lecturing to general practitioners, with teaching GPs, is that there is an amazing ignorance amongst the medical profession about the health effects of flying" (Q 147). Indeed we contacted the Royal College of General Practitioners to find out what proportion of the postgraduate medical syllabus for trainee general practitioners feature aviation health. They told us there is no mandatory training for GPs in aviation medicine. This despite the fact that the BMA, in The Impact of Flying of Passenger Health, has stated:

"Healthcare professionals should be appropriately educated concerning the potential risks to health from flying. The BMA believes that undergraduate and postgraduate training curricula should include the relevant aspects. In-depth, specialised courses should be made available for those with a particular interest."

4.65.  At the same time, there is considerable information available to GPs, for example publications such as Managing Passengers with Respiratory Disease Planning Air Travel, published by the British Thoracic Society, The Impact of Flying of Passenger Health from the British Medical Association, and others from the WHO and AsMA. However, these specialist sources of information have not been pooled in a single publication for ease of reference. We also return to the issue of access. Most of this information is provided via the Internet, and we question how accessible it is from a doctor's surgery when a patient requests clearance to fly from their GP.


4.66.  We recommend that the Government and the regulators review the manner in which information on fitness to fly is offered, giving due consideration to their target audience. As the authoritative provider of information for passengers on air travel and health, the Government must ensure that information is available to all, not just people who have Internet access.

4.67.  We recommend that the general practitioner postgraduate curriculum should include a basic overview of aviation medicine. Continuing professional development in the form of specialised courses should be made available for healthcare professionals with an interest in this area.

4.68.  We further recommend that various specialties such as cardiology, orthopaedics and psychiatry follow the lead of the British Thoracic Society in producing guidelines on fitness to fly with the intention of informing GPs and other healthcare professionals; and that these publications should be made available in electronic form and hard copy to all GPs. In the course of time the collection of these guidelines would form a valuable (paper) reference manual.

34   See Back

35   op. cit. Science and Technology Committee Air Travel and Health 2000, paragraphs 6.33-6.50. Back

36   See Back

37   See Back

38   See Back

39   For a detailed account see Science and Technology Committee, 4th Report (2005 06): Pandemic Influenza (HL 88) Back

40   See Back

41   See Back

42   See Back

43   See Back

44   See Back

45   op. cit. Science and Technology Committee Air Travel and Health 2000, paragraph 4.41. Back

46   AHWG Minutes 27 October 2004 Back

47   See Back

48   See Back

49   HL Deb 8 Dec 2005 col GC132 Back

50   See Back

51   See Back

52   See Back

53   See Back

54   See Back

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