Select Committee on Science and Technology Fifth Report


Other main findings


1.48 Key points to note from our survey of the regulatory structures are that:

    (a)  no part of the Chicago Convention requires ICAO Member States to have regard to the health and comfort of air passengers;

    (b)  CAA's prime responsibilities for passengers are to regulate for their safety - it has no direct responsibilities for passenger health or comfort, although we note that the US Department of Transportation has extended FAA's activities into certain areas of passenger health, notably tobacco-smoking in aircraft, cabin ozone levels, and cosmic radiation; and

    (c)  HSE has no active responsibilities in relation to the health of airline passengers or crew. (Paragraph 3.25)

1.49 The charge that the industry was "in a state of denial" about passenger health is perhaps a harsh one, but the industry could do more to avoid such charges. To all those with responsibilities for passenger and crew health, we have to say that absence of evidence of harm is not the same as evidence of the absence of harm. Without succumbing to the impossible counsel of perfection that everything should be demonstrated to be completely safe in all possible circumstances, there is much scope not only for more positive responses to health issues when they are raised, but also for pro-activity in detecting, examining and dealing with new and emerging concerns. (Paragraph 8.16)


1.50 The fundamental problem is the general lack of recognition by the public and their primary health advisers that fitness to fly is a serious matter. We consider that this is due to a lack of knowledge about the possible health risks in the aircraft cabin environment amongst not only the public but also the health professions. Intending flyers need to be aware of fitness to fly issues so that the small minority of them who need advice can identify themselves and, in seeking advice, stimulate demand from health advisers for better and more accessible guidance. (Paragraph 8.47)

1.51 The vast majority of intending air travellers are people who either are healthy or have no reason to think they are not. They are unlikely to seek professional health advice before embarking on their journeys - and we agree with the Minister for Public Health that most people have no need to do so. (Paragraph 8.46)

1.52 The Minister for Public Health acknowledged a case for more targeted information for people at risk, but noted that not enough was currently known about the target groups and what advice they should be given. The former should be clarified in the new research initiated by DETR and DoH. On the latter, the Minister made a good start by noting in her evidence to us four particular groups of people who might need advice about health risks of flying. (Paragraph 8.50)


1.53 From the incidence among the general population, it is certain that a number of people will develop DVT while travelling or soon after they have travelled by air. The fundamental question yet to be answered is whether this number is greater than the number from an equivalent population who would have developed DVT if they had not recently flown. The time-scale between flight and the development of DVT is important because the anecdotal evidence indicates that flight-related DVT may develop, or be diagnosed, at any time from in-flight to many days post-flight. (Paragraph 6.17)

1.54 We note in Box 2 that, while age over 40 is a risk factor for DVT in general, travel-related DVT seems to strike the young as well as the old. We consider that, in women, this may be related in part to the widespread use of oestrogen hormones in oral contraception, and we draw attention to this and hormone replacement therapy (HRT) in Box 4. (Paragraph 6.21)

1.55 For healthy individuals, the risk of getting a clinically significant DVT solely because they are taking a flight seems to be exceedingly small. For those who are already at risk because they are subject to predisposing factors, there may be an additional risk from flying, but it is not currently quantifiable. (Paragraph 6.24)

1.56 Other research into any relationship between flying and DVT, as suggested by a number of witnesses, seems premature until the statistical facts of any link have been established, in which the outcome of current studies may be very helpful. As there is a public health issue here that is wider than air travel, the suggestion of a National Register for travel-associated DVT has considerable merit but, to avoid what might prove to be unnecessary expenditure of scarce resources, we see no case for pursuing this in advance of the outcome of the recommended research by case-control studies. (Paragraph 6.26)


1.57 The JAA and CAA regulatory requirements for seating relate only to safety. They do not include any consideration of passenger comfort, and there is no regulation to relate either passenger numbers or seat spacing to the type of operation concerned. (Paragraph 6.33)

1.58 We believe that the introduction of "premium economy" seating is a good answer to the demand for space above a reasonable minimum. We recognise - and the industry needs fully to recognise - that there is no such thing as a standard passenger with standard aspirations. Passengers are, of course, free to purchase whatever seating they wish. The point we make several times in this Report is that passengers' choices should be properly informed. (Paragraph 6.48)


1.59 Because the volume of air supplied to the cabin continues to provide ample quantities of oxygen, and because the rate at which cabin air is exchanged keeps carbon dioxide and other internal-source contaminant levels to well below those of significance to health, we do not accept the widely held view that the introduction of re-circulatory ventilation systems has resulted in any harmful change in the quality of cabin air. Nevertheless, the industry should pay attention to these common perceptions of the effects of re-circulation. (Paragraph 5.16)

1.60 While the regulatory situation as far as passengers' needs are concerned is chaotic, the vast majority of aircraft operate at a cabin fresh air supply rate of 10 cubic feet per minute (cfm) or more per person. This is an average rate and, because the supply air flow per unit length of the aircraft is the same throughout all cabins, economy class has a lower air flow per passenger than in classes with less dense seating. Nevertheless, Boeing drew our attention to the fact that, even if one of their standard aircraft was configured for maximum density seating throughout, the fresh air flow would still be between 6.5 and 8.0 cfm per passenger. As noted in paragraph 4.7, this volume of air supplies at least 30 times more oxygen than needed for normal respiration. (Paragraph 3.37)

1.61 The typical cabin air flow of 20 cfm of air per occupant equates to a full change of cabin air every 2 to 3 minutes, i.e. 20 to 30 times per hour. As half of the air being changed is re-circulated cabin air, this is equivalent to an entire exchange of cabin air with fresh air 10 to 15 times per hour. (Paragraph 5.5)

1.62 In modern aircraft, the environmental control system (including the pressurisation system) is entirely automatic, being controlled by appropriate sensors and valves - although some aspects may be manually controlled from the flight deck, in particular the fresh and re-circulated air flows, the number of air-conditioning packs in operation and zone temperatures. (Paragraph 5.9)

1.63 A common allegation is that, to save fuel, flight crew shut down some of the air-conditioning packs and thereby reduce air quality below the intended standard. That would be inexcusable if true. However, we find BALPA's rebuttal conclusive. The regulatory emergency requirement means that there is an inherent over-capacity in a fully serviceable environmental control system. (Paragraph 5.10)


1.64 The very great majority of passengers can easily accommodate the reduced availability of oxygen in cabin air. Being generally at rest with consequently reduced need for oxygen, very few passengers are likely even to be aware that they are in a reduced oxygen environment. (Paragraph 4.7)

1.65 Cabin crew work may sometimes be sufficiently heavy for cabin oxygen levels to have a noticeable impact on metabolism particularly in increasing respiration, pulse rate, and fatigue. However, we consider that these are normal physiological responses, and that repeated exposure to the environment would be unlikely to have an adverse effect on health unless an individual were already unwell from another cause. (Paragraph 4.11)


1.66 Temperature is one of the most quickly sensed aspects of the aircraft cabin environment. Being too hot or too cold is likely to affect a passenger's general perception of the whole flight experience. We endorse ASHRAE's suggestion that further work should be done to establish guidelines for cabin thermal conditions and we look to the industry to carry this forward. (Paragraph 5.39)

1.67 We are satisfied that low cabin humidity is not intrinsically harmful. Any uncomfortable dryness of skin, mouth, nose and throat can be alleviated simply by a sip of water or other local application of moisture and is not a threat to health. On a long flight, assuming normal fluid intake, one glass of water can more than offset any additional loss due to low cabin humidity. The common advice to drink a little more water than usual is thus sound. (Paragraph 5.35)


1.68 Our two main witnesses on the health effects of insect control procedures said that they were unaware of any UK cases of ill health from exposure to pesticides in aircraft, and that they had received surprisingly few inquiries about such exposures. We share their view that insect control procedures are not a significant health issue. (Paragraph 4.28)

1.69 Under normal operating conditions, volatile organic compounds in cabin air were found to be either undetectable or at very low levels of up to 3 parts per million (ppm) - of which the majority (80%) were alcohols from alcoholic drinks. These levels are far below the 1,000 ppm total workplace limit and below the workplace limit for any single component. We thus conclude that cabin atmosphere levels of volatile organic compounds present no risk to cabin occupants under normal operating conditions. (Paragraph 4.33)

1.70 Notwithstanding the availability and use of filters that can remove volatile organic compounds, every effort must be made to avoid such contamination in the first place. (Paragraph 4.34)

1.71 The smell of fumes from other aircraft while manoeuvring on the ground is a matter of annoyance for some rather than a health hazard. Problems could be reduced by odour-eliminating filters and, to increase passenger comfort, airlines may wish to consider installing these. (Paragraph 4.49)

1.72 The absence of confirmed cases of tri-ortho-cresyl phosphate (TOCP) poisoning from cabin air and the very low levels of TOCP that would be found in even in 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. (Paragraph 4.41)

1.73 There are no known ill effects or biochemical effects from being exposed continuously for many weeks to carbon dioxide levels of 0.5 to 1%, i.e. five to ten times the normal aircraft cabin levels. We therefore conclude that the carbon dioxide levels normally found in the aircraft cabin atmosphere are of no adverse consequence to health. (Paragraph 4.14)


1.74 On the evidence we have been given, it seems to us that the risk of transmission of infection due specifically to being in the aircraft cabin environment is no greater than elsewhere, provided circulation and filtration systems are working properly. Given the evident success in avoiding transmission of major infections, we do not agree with those who seem keen to attribute any travel-related infectious ailment to augmented transmission within the aircraft cabin environment. (Paragraph 7.17)

1.75 The theory, the facts and the vast majority of our specialist witnesses all support the conclusion that HEPA filtration, if properly installed and maintained, should remove the possibility of cross-infection that would otherwise exist in re-circulatory cabin air systems. We agree that, on the evidence presented to us, the modern aircraft cabin environment generally poses no greater risk of transmission of infection between its occupants than crowded situations elsewhere - and may, indeed, be safer than most of them. (Paragraph 7.25)


1.76 The most commonly quoted of many factors associated with stress and air travel are listed in Box 5, and we emphasise that these include pre-flight activities. In our view, some of these factors, particularly in combination, may well give rise to the feelings of general malaise which people often attribute to poor quality cabin air. Even if such factors do not give rise to illness itself, they may cause detriment to the condition of the ailing or infirm. (Paragraph 6.62)


1.77 Our deliberations on the aircraft cabin environment have revealed relatively few health concerns for the great majority who are in normal health. However, as the age and health spectrum of those travelling by air widens, more and more people are flying with pre-existing or previously unsuspected medical conditions, which might be compromised by the cabin environment. We give some general guidance on these matters in paragraphs 7.46-7.72, although this is no substitute for personal medical advice. Intending passengers with any doubts about their fitness to fly should discuss these matters with their medical advisers and with the airline (or its agents) at the earliest possible opportunity. (Paragraphs 7.42 and 7.44)

1.78 It is not realistic to require airlines to accept as passengers everybody who might wish to fly, which is why aircraft are exempted from the requirements of the Disability Discrimination Act 1995 specifically pertaining to the transport of passengers, including means of access standards. Airlines have, however, a commercial imperative as well as a wider social responsibility to make reasonable provision for people with disabilities. We applaud the improvements achieved through the International Air Transport Association (IATA) and encourage the industry as a whole to keep the matter under continuing and positive review. (Paragraph 7.48)


1.79 Cosmic radiation is different from other aspects of the aircraft cabin environment since exposure is intrinsic to air travel rather than a consequence of design considerations. Exposure to radiation and the consequent risks of cancers or inheritable mutations can be an emotive topic, although very few concerns were raised with us during this Inquiry. We are assured that the health risk from cosmic radiation exposure during flight represents an insignificantly small addition to the range of other factors that could lead to cancer or inheritable mutations. In view of this and the legislative controls currently coming into force, we conclude that the matter does not require further comment or recommendations in this Report. (Paragraph 3.65 and 3.67)

1.80 The extensive written and oral evidence from the National Radiological Protection Board (NRPB) is, in our view, highly reassuring. However, while it is technically correct to talk of risks in terms of "so many per million", these are not easy for non-specialists to appreciate and put into context. NRPB confirmed our proposed simplification that, because the radiation from the earth's crust in Wales is a quarter of that in Cornwall (although of no significance to health in either place), a day a week at cruising height has the same consequences as living permanently in Cornwall rather than Central Wales. We invite NRPB to explore other ways of making these important points more accessible and understandable for the public. (Paragraph 3.66)


1.81 The starting point of our Inquiry was to be a review of current knowledge about the health implications of the commercial aircraft cabin environment and the extent to which this informed current practice. While we acknowledged the possibility that there might be some gaps in that knowledge, we were surprised to find that there were so many. In the absence of accessible and authoritative information, it is not surprising that rumour and speculation thrive. We therefore welcomed the Minister's announcement at our final evidence session that, explicitly prompted by our Inquiry, DETR and DoH were initiating new wide-ranging research into air travel and health. (Paragraphs 8.17 and 9.2)


1.82 An important source of information for passengers is journalism. The challenge for journalists in this area is to provide accurate information without causing unnecessary concern, particularly among those who have some fear of flying - who probably number many more than those who openly admit it. This calls for careful judgement about language and presentation. It cannot be right to side-step potential health problems by knowingly underplaying the significance of cabin factors for health. It is equally unacceptable to overplay the health significance of such factors. (Paragraph 8.35)

1.83 In our recent Report Science and Society, we commented extensively on the role of the press and other media in informing and educating the public on scientific matters, and of the need for them to act responsibly in presenting sometimes complex questions of uncertainty and risk. All those points apply in the handling of information about the health effects of flying, and we again commend to journalists the guidance outlined in Chapter 7 of Science and Society. (Paragraph 8.36)


1.84 DETR noted that, in the air travel market, the usual rule of "buyer beware" applies. This was also one of the general thrusts of the airlines' evidence. It is therefore vital that sufficient information is available at the point of sale to enable the purchaser to make an informed choice. In our view, airline ticket selling does not satisfy this need, particularly for those intending air-travellers who are concerned about their health and wellbeing - and those who are not concerned, but should be. (Paragraph 8.52)

1.85 Even at the check-in stage, passengers have found that they are often treated as commodities. If they try to enquire about conditions on board, or get seats or groups of seats that they particularly want, they are made to "approach the check-in desk as supplicants rather than partners to an equal-sided contract". We hope that the European Commission's initiative, noted in paragraph 3.15, will lead to legislation to improve the information available to passengers to make well-founded choices, to create new rights for passengers, and to improve the balance of contracts in their favour. Further, we hope that airlines' actions before then will render such legislation redundant. (Paragraphs 8.55 and 8.56)

1.86 Airlines and their agents need to be aware that the implementation of our recommendations for improving the aircraft cabin environment and the public's awareness of health issues will lead to increased dealings with their customers. To the extent that these are not handled well at the normal stages of ticket purchase, check-in and flight, they may lead to an increased number of complaints. (Paragraph 8.59)


1.87 We conclude by noting that the airline industry is international and highly competitive. To avoid financial and operational disadvantage for UK airlines, we can understand DETR's reluctance to impose change applicable only in the United Kingdom, but that is not a conclusive argument. We welcome the Minister's agreement that the United Kingdom could, if necessary, act unilaterally on air travel health matters. It is, of course, entirely possible that positive changes could be a marketing advantage for airlines. (Paragraph 9.9)

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