CHAPTER 3: REGULATORY
Principal health-related regulatory requirements
3.27 Although national and
international regulations are intended primarily to ensure the
safety of aircraft and their occupants, several of these impact
directly on the health and comfort of passengers and crew. The
requirements and rationale for each are discussed below, in most
cases as a guide to more detailed discussion later in the Report.
CABIN STRUCTURE AND PRESSURISATION
3.28 Commercial aircraft
cruise at up to around 40,000 feet where the external conditions
would be lethal for unprotected humans. Atmospheric pressure
decreases with height and, at that altitude, is only about 20%
of that at sea-level.
This thin air provides insufficient oxygen to support human life.
Moreover, the air is very cold, at about minus 50-60ºC.
3.29 To provide an atmosphere
with sufficient oxygen, aircraft cabins are pressurised in flight.
Under normal operating conditions, the pressure inside the cabin
- even at cruising altitudes - is not less than would be found
outside the aircraft at 8,000 feet.
In fact, most modern aircraft have an effective cabin altitude
of between 6,000-7,000 feet. Safety regulations also require that
occupants are not exposed to a cabin pressure lower than would
be found outside at 15,000 feet. If cabin pressure were suddenly
lost at cruising height, the occupants would quickly lose consciousness.
In such circumstances, there is a safety requirement for drop-down
oxygen masks supplying 100% oxygen to cabin occupants until the
aircraft has descended to a safe altitude.
3.30 The physiology of human respiratory needs is
discussed in Chapter 4 as one of the aspects of healthy cabin
air. The mechanics of pressurisation (and temperature control)
are discussed in Chapter 5 as part of the practical provision
of such air. Both those sections also discuss the health issues
3.31 As discussed in paragraphs 5.41ff, rates of
change of pressurisation on ascent and descent have some implications
for comfort and health. These rates are not, however, subject
3.32 The material structure of the cabin, its doors,
its windows, and partitions between pressurised and non-pressurised
parts of the aircraft must be strong enough to withstand any pressure
differential they may encounter, and light enough to meet aerodynamic
requirements. All the design and operating standards and features
necessary to meet these structural needs throughout the life of
the aircraft are laid down, controlled and monitored by the regulating
aviation authorities (FAR/JAR 25).
3.33 Until 1996, both FAA
and JAA had the same basic requirement for cabin ventilation rates.
FAR 25.831 and JAR 25.831 required a minimum supply of 10 cubic
feet per minute (cfm)
of fresh air per flight crew member, which "must be free
from harmful or hazardous concentrations of gases or vapours"
with specific maximum concentrations for:
- carbon dioxide at 5,000 parts per million by
- carbon monoxide at 50 ppm; and
- ozone at 0.1 ppm (short-term emergency maximum
3.34 The FAR required that
ventilation would "provide reasonable passenger comfort"
but the JAR made no reference to passenger requirements. In June
1996, FAA introduced Amendment 87, by which the ventilation design
requirement of 10 cfm of fresh air would be required "per
occupant", as opposed to "per flight crew member".
However, JAA did not follow suit because of industry concerns
about the ability of new aircraft to meet the new regulation in
some cases. For the same reason, US industry petitioned FAA against
the Amendment. FAA/JAA harmonisation on regulation 25.831 is being
attempted but, as JAA noted, is proving contentious, particularly
in relation to the ventilation air supply parameter "per
occupant" or "per flight crew member" (p 130).
3.35 The current regulatory
position is that, while FAA currently requires 10 cfm of fresh
air per cabin occupant, JAA has no passenger cabin ventilation
requirement other than a guideline figure cited by Airbus Industrie
of "0.4 lb/min (7.3 cfm at the maximum effective cabin altitude)
of fresh air per passenger as a minimum comfort level when only
one air-conditioning pack is operative". This latter guidance
is expressed differently by JAA as a recommendation for "improbable
failure conditions" of "not less than 0.4 pounds of
fresh air per minute per crew member for any period exceeding
five minutes" (p 130).
3.36 To summarise, for
the main purpose of airworthiness certification, JAA currently
has no specific cabin air supply requirements for passengers,
and the FAA requirement is seen by manufacturers as, in some cases,
impossible or impracticable. Because of the intrinsic importance
of the matter and also to clarify matters which, as our evidence
has shown (Appendix 4), cause great public concern, we recommend
the Government, CAA and JAA to find a practicable way forward
as soon as possible.
3.37 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 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
(p 204). As noted in paragraph 4.7, this volume of air supplies
at least 30 times more oxygen than needed for normal respiration.
3.38 As will be discussed in paragraphs 5.4 and 5.5,
modern passenger aircraft are ventilated with a mix of fresh and
re-circulated air. Regardless of the regulatory
muddle, the major aircraft manufacturers work to a design cabin
air supply requirement of 20 cfm of air either "per person"
or "per passenger" of which at least 10 cfm is fresh
air. In supplementary material (Q 427), Airbus Industrie stated
that all its current production aircraft provided 12 cfm of fresh
air per person plus 8 cfm (40%) re-circulated air, while Boeing
(p 204) provides 10 cfm of fresh air plus another 10 cfm (50%)
of re-circulated air, both giving the same cabin air supply of
20 cfm per person.
3.39 The regulations do not make detailed specifications
for such re-circulatory systems, except to require that the design
fresh air provision can be maintained if the re-circulatory systems
are shut down for any reason. In particular (as discussed in paragraphs
5.18ff), there is no requirement for filtration. However, where
re-circulatory systems and filters are installed, operators are
required either to use and maintain them in accordance with the
manufacturer's specifications or to secure CAA agreement to different
3.40 It is also required
that: to avoid contamination, air must be ducted through compartments
inaccessible during flight; the minimum fresh air must be capable
of being supplied when one source is lost; and ventilation and
temperature controls for all compartments of the aircraft must
be accessible to the flight crew. JAA also requires that, for
safety reasons, the flight crew compartment conditioned air supply
must be separated from the general cabin air supply, and consist
only of fresh air (p 130, Q 363). While FARs regulate for thermal
conditions in the cabin (relating temperature and humidity to
exposure time), JARs do not.
3.41 Ventilation is discussed further in Chapter
5 as one aspect of providing a healthy cabin atmosphere.
3.42 For clarity throughout
this Report, we use:
(a) "aircrew" to refer to all the
personnel employed to work in aircraft;
(b) "flight crew" to refer to pilots
and flight engineers employed only on the flight-deck; and
(c) "cabin crew" to refer to those
working only in the passenger cabin and associated areas such
3.43 ICAO, JAA and FAA require
only flight crew to be subjected to regular medical examination,
in order to maintain the validity of their flying licences. The
purpose of medical certification is to ensure that the licensed
person is medically fit to "exercise the privileges of"
the licence. The examination is concerned with individuals' health
only insofar as it might interfere with the safe performance of
their duties, or render them likely to become suddenly unable
to operate aircraft safely or to perform assigned duties safely.
The qualifications of the medical examiner, the examination procedures
to be used, the standards required, and the frequency of examinations,
are all laid down in the relevant regulations. The medical examiners
appointed by CAA are aviation medicine specialists, known as Authorised
Medical Examiners (AMEs).
3.44 Between licence examinations,
flight crew are responsible for assessing their own fitness to
fly. They can ground themselves with or without medical advice
if they think they are unfit for any reason. They inform their
employing airline and CAA accordingly, and the latter may require
re-certification by an AME before restoring flying privileges.
Although the AME may in some cases additionally be an airline
employee, airlines normally have no direct jurisdiction over the
medical fitness to fly of their flight crew.
3.45 The important points about these procedures
(a) an airline may have no information about
the health of its flight crew other than their medical certification
as fit to operate;
(b) CAA is not concerned with the general and
long-term health of flight crew unless it impacts on their medical
(c) although an individual's general practitioner
(GP) may have information about the person's health, because of
medical confidentiality requirements, the GP will not normally
release such information to airlines or to CAA without the individual's
3.46 We asked the main staff organisations representing
UK pilots and cabin crew for their views on the monitoring of
aircrew health as opposed to their fitness to fly. The British
Air Line Pilots Association (p 213) stated that there had not
been a great deal of data collected on the long term health of
flight crew, and they indicated that one of the difficulties CAA
expressed on this matter was that that pilots are lost to CAA's
medical data bank when they retire. The Transport and General
Workers Union (p 287) said that they were not aware of any existing
studies or data that might be of help to us but did enclose a
cabin crew survey, of the self-reporting type on which we comment
in paragraph 8.22. On behalf of Cabin Crew '89, the Amalgamated
Engineering and Electrical Union stated that it would be in everyone's
interest to have an independent scientific study on passenger
cabin air quality, although they were unaware of any clearly proven
problems. We received no views at all from aircrew or their representatives
about medical needs for the protection and preservation of their
long term health. Indeed, JAA said that pilots' unions actually
disagreed with the giving of preventive medical advice to pilots
by their certifying medical examiners (p 130). This attitude compounds
the dearth of information on aircrew health indicated in the immediately
3.47 Cabin crew are not required to be subject to
licence procedures, and thus are not subject to regular medical
They are required, however, to pass an initial medical assessment
as part of the recruitment process to ensure that they are fit
to carry out their duties (JAR-OPS 1.995), and they must ensure
that they remain medically fit to discharge them.
3.48 We were surprised at
the lack of attention - by regulators, airlines, and aircrew trade
unions - to the health of aircrew. We are aware that there are
serious issues of medical confidentiality and job security involved.
Nevertheless, we recommend that the present rules, agreements,
and attitudes regarding the monitoring and recording of the general
health of aircrew, over and above their fitness to operate, should
be reconsidered urgently. This would benefit aircrew themselves
and would also provide a sound body of evidence on which to judge
the impact of the aircraft cabin environment on health.
In the case of pilots, who are already subject to regular
medical examinations, including blood tests where appropriate,
we recommend that, if the AME finds evidence significant ill-health
not necessarily affecting a pilot's fitness certification, this
should be recorded and reported both to CAA and to the affected
person's general practitioner.
3.49 CAA's Airworthiness
Notice 64 includes several minimum dimensions between seats.
The one of most significance to health and comfort is a minimum
distance of 26 inches between the back support cushion of a seat
and the back of the seat or other fixed structure in front of
it. The dimensions and other regulations are intended to ensure
that the majority of passengers can sit upright, stand up from
the seat, and move to the aisle without undue difficulty. Every
aircraft's seating configuration has to be agreed by CAA.
3.50 JAA and CAA require
seats to be designed to help protect passengers from injuries
caused by air turbulence, high acceleration and deceleration events,
and crash conditions. The requirements 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.
Whatever the room intended to be available between seats, the
space available for movement of feet and legs is sometimes reduced
by the safety requirement that hand-baggage not stored in overhead
bins must be placed beneath the seat in front, at least during
take-off and landing.
3.51 CAA requires operators
to demonstrate that, for safety purposes, everyone in an aircraft
can be disembarked within 90 seconds. We were pleased to hear
about new CAA research into people's size and the reduction in
mobility after long flights to ensure that the emergency evacuation
requirements are in line with modern circumstances (Q 13).
Given changes over the years in the length of flights and in the
sizes, ages and health states of people undertaking them, we recommend
that this research be completed
3.52 Seating and space are discussed further in paragraphs
3.53 All civil passenger
aircraft under JAA (and FAA) jurisdiction are required to carry
basic first aid equipment and the airlines are required to train
their aircrew in first aid procedures. As noted by the Consumers'
Association and the Aerospace Medical Association (AsMA), they
have also to carry an additional kit for professional medical
use in emergency (pp 59 & 198).
3.54 The handling of in-flight medical emergencies
is considered further in paragraphs 7.76ff.
OTHER IONISING RADIATION
3.55 Control of exposure
to cosmic and other ionising
radiation in aircraft is a recent addition to the regulatory arrangements.
Drawing principally on material submitted by the UK National Radiological
Protection Board (NRPB) (p 146, QQ 391ff), British Airways (p
99) and the Mullard Space Science Laboratory (p 253), this section
deals with the possible hazards to crew and passenger health from
3.56 The principal source of ionising radiation in
the aircraft cabin is cosmic radiation, which comes from both
outer space and, less significantly (except under rare conditions
mentioned in 3.64), the sun. Cosmic radiation is absorbed as it
passes through the Earth's atmosphere, but the energy of the radiation
means that there is no practicable way of preventing it passing
through an aircraft at altitude. Flying exposes passengers and
crew to more radiation than generally experienced at ground level
but the doses received are of very little significance to health,
as discussed in paragraphs 3.59ff.
3.57 The amount of exposure depends not only on the
length of flight but, as cosmic radiation is affected by the Earth's
magnetic field, also on the altitudes and latitudes which the
aircraft traverses. Increased cosmic radiation exposure at altitude
is counterbalanced to some extent by reduced exposure to sources
of background radiation at ground level. Although there may be
some additional radiation within the aircraft cabin (e.g. from
radioactive materials in smoke detectors and sign lights), their
contribution to the overall cabin radiation level is very small
3.58 Ionising radiation, including cosmic radiation,
is measured in a unit called the Sievert (Sv). This summates the
effect on the body of radiation exposure taking into account the
type and energy of the radiation. Doses of radiation received
from cosmic sources and the many ground sources, including natural
background radiation, are so small that they are expressed in
milli- (one thousandth) or micro- (one millionth) Sieverts: mSv
or µSv respectively.
3.59 The annual radiation
dose which the average member of the UK population receives from
natural and artificial sources at ground level is about 2.25 mSv.
Individuals may receive anything between 2 and 8 mSv depending
on their jobs and recreation, the medical procedures they may
have undergone and, in particular, the part of the country where
they live (Q 393). The International Commission on Radiological
Protection (ICRP) sets dose limits in the light of two main risks
- the induction of cancer and inheritable mutations in germ cells
- and assumes (a) that both risks increase proportionally with
dose and (b) that there is no dose below which there is no risk
(Q 299). ICRP's current recommendations are that exposure over
and above that received from normal background sources should
- mSv per year for the general public;
- mSv for the foetus during pregnancy; and
- mSv for persons occupationally exposed to radiation
by their jobs - which includes aircrew.
3.60 Radiation levels typically found in aircraft
cabins during flight at cruising altitudes are around 5 µSv
per hour at polar latitudes, and about half that at the equator.
An individual would need to fly for about 200 hours at polar latitudes
or 400 hours at the equator to reach the general public allowed
annual dose, and could take about 40 transatlantic flights a year
by Concorde without exceeding the general public limit. (A simple
comparison of cosmic radiation exposure from flying with exposure
from background radiation is given in paragraph 3.66.)
3.61 The ICRP recommended limits have been incorporated
into both European and United Kingdom legislation,
but not yet into US legislation (QQ 407-409). NRPB has examined
the ICRP limits in relation to airline passengers and crew and
is satisfied that, with the exception of a very few frequent flyers,
passengers are at no risk of exceeding the general public limit.
Although frequent flyers who routinely fly as a major part of
their jobs would appear to be occupationally exposed, they are
not included in either the European Directive or the United Kingdom's
legislation. Nevertheless, NRPB considers that a risk assessment
on them should be undertaken by their employers (Q 405)
3.62 Although aircrew are defined as occupationally
exposed under the Directive, they are not so defined under the
United Kingdom's Air Navigation Order as it presently stands.
Nevertheless, some airlines are using the requirements of the
Ionising Radiations Regulations as if they applied to aircrew
(pp 99, 104, 107 & 229). The Regulations set a working action
level of 6 mSv per year, and if any workers are liable to exceed
this level, special measures must be taken to monitor, control
and limit their exposure. If they are liable to receive between
1 mSv (the general public limit) and 6 mSv per year they are required
to have their exposure assessed and work schedules organised to
keep annual exposure below 6 mSv per year. In addition, occupationally-exposed
workers must be informed of the health risks involved. The Ministry
of Defence's Defence Evaluation Research Agency (DERA) brought
to our attention a personal cosmic radiation dosimeter it has
developed for military aircrew whose operational flying experiences
are, by their nature, unpredictable (p 250).
3.63 Measurement and calculation
show that the vast majority of aircrew do not exceed about 4 mSv
per year, and the NRPB stated that the average annual dose for
all aircrew is about 2 mSv
(p 146). The only crew members who might exceed the 6 mSv level
would be those who fly only ultra-long-haul transpolar routes,
but this can be avoided by appropriate crew scheduling. The ANO
already incorporates requirements for cosmic radiation exposure
records, and UK airlines are now monitoring and recording the
cosmic radiation exposure of all affected aircrew. It is common
airline practice to ground female aircrew on declaration of pregnancy,
and this would ensure compliance with the foetus protection limit.
3.64 The only situation in
which aircrew could receive cosmic radiation doses in excess of
the limits would be in the event of a large solar flare during
the most active part of the solar cycle, which peaks every 11
years. Such a flare may yield a burst of high-energy radiation
over a period of a few hours which reaches Earth at flying altitudes.
These are very rare events. For example, although Concorde has
radiation monitoring equipment on board to warn of such events,
none has been recorded in its lifetime. (pp 99 & 146). The
evidence from members of the Mullard Space Science Laboratory
noted a possible such event in April 2000 (p 253), but we understand
from the NRPB that this event did not affect cosmic radiation
levels at cruising altitudes.
3.65 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.
The topic was not mentioned by either BALPA (p 213) or the International
Association of Flight Attendants (AFA - p 245). The International
Air Passenger Association (IAPA) noted it as an issue on which
it did not have a position (p 243). Mr Kahn of the Aviation Health
Institute raised extensive concerns in respect of passengers and
crew (p 44). His points seem effectively rebutted by the sources
noted by Varig (p 288).
3.66 The extensive written
and oral evidence from NRPB (p 146, QQ 378-424) 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 (Q
421). We invite NRPB to explore other ways of making these
important points more accessible and understandable for the public.
3.67 In the meantime, 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.
22 A manifestation of the air's density or number of
gas molecules per unit volume. Back
The standard atmospheric pressure at sea level is, as in some
of the evidence submitted to us sometimes referred to as either
1 atmosphere (atm) or 760 mmHg, the latter being the height of
mercury (Hg) in an old-fashioned barometer. Back
A domestic deep freeze operates at about minus 18ºC. Back
JAR 25.841 Back
JAA's volume measures are applied at the standard effective cabin
As FAA uses a weight of air measurement unit (which removes the
need for defining the effective altitude), its FAR 25.831 expresses
this as 0.55 pounds per minute (lb/min). Back
"Parts per million" (ppm) are the conventional way of
referring to low concentrations. 1 ppm is equal to 0.0001%. Back
Airbus Industrie, in response to Q 427, and Boeing, with its evidence
on page 204, submitted a number of articles from company publications
on cabin air on which we have drawn in this Report. We refer to
these as supplementary evidence from Airbus Industrie and Boeing. Back
This was presumably one reason why manufacturers petitioned against
FAA Amendment 87, as noted in paragraph 3.34. Back
Under JAR-FCL 3, flight crew are subject to licence medicals annually
up to the age of 40 and 6-monthly thereafter. Back
The European agreement noted in paragraph 3.17 offers the prospect
of some change in due course. Back
A point we discuss further in paragraph 8.23. Back
High energy radiation which can damage body cells and other molecular
At Concorde's higher cruising altitudes, the levels are about
twice these - although this is effectively cancelled out by the
shorter journey time. Private business jets are outside the scope
of our Inquiry, but we understand from the NRPB that they routinely
fly at very high altitudes, approaching those used by Concorde
(p 146). Being subsonic, they also spend longer at those heights. Back
EC Directive 96/29/EURATOM 1996 and UK Ionising Radiations
Regulations 1999. Article 42 of the Directive applies to aircrew
as occupationally exposed workers, but the UK regulations do not
apply to aircrew. Article 42 is being incorporated into the Air
Navigation Order but, with the exception of protection of the
foetus (see paragraph 3.59), dose limits for aircrew exposure
are not specified, largely because it is difficult to envisage
anyone being in the air long enough to exceed a dose of even 10
Concorde crew doses might be a little higher but do not reach
the 6mSv level. Back
For example that, compared to the overall lifetime risk of developing
a fatal cancer of 1 in 4 (Q 424), the additional lifetime risk
from a 20 hour return flight is about 1 in 1 million (Q 418). Back