ideal cabin environment (ice) project · • cabin occupants (passengers and cabin crew); •...

1 Ideal Cabin Environment (ICE) Project – Publishable Report

Ideal Cabin Environment (ICE) Project Prepared for: Hans von den Dreish Scientific Officer European Commission 29 June 2010

BRE Garston WD25 9XX T + 44 (0) 1923 664000 F + 44 (0) 1923 664010 E [email protected] www.bre.co.uk

This report is made on behalf of BRE. By receiving the report and acting on it, the client - or any third party relying on it - accepts that no individual is personally liable in contract, tort or breach of statutory duty (including negligence).

mailto:[email protected]

http://www.bre.co.uk


Executive Summary

The overall conclusion of the now completed ICE (Ideal Cabin Environment) project showed that

flying in current commercial aircraft environments poses, in general, no significant health risk for

passengers.

This eight-nation research project was carried out within the European Commission’s 6th

Framework Programme and was completed in March of this year after just over three years of

extensive study. The overall aim of ICE was to provide airframers and airlines with step-change

knowledge and innovations to address the concerns about the unknown combined effects of

cabin environmental parameters, including for the first time cabin pressure, on the health of

passengers in commercial aircraft.

ICE addressed the widespread concerns about the impact of flying on the health and well-being

of passengers. Changing passenger demographics, the advent of ultra-long-haul services, and

specific health issues such as deep vein thrombosis (DVT), had all combined to increase

concerns. The key objectives of ICE were to determine health-based optimum levels of cabin

environmental parameters and their synergistic effects on, amongst others, hypoxia (often

considered the most serious single physical hazard) and possible links with DVT.

Nearly 1,500 volunteers took part in eight-hour ‘flights’ in simulated aircraft cabin facilities at the

Fraunhofer Institute for Building Physics in Holzkirchen near Munich, Germany, and at the BRE

Group’s Watford headquarters in the UK. A team of researchers, medical experts and cabin

environment specialists investigated the effects on passengers of a range of cabin conditions

including, for the first time, cabin pressure.

The tests simulated a long-haul flight experience with realistic cabin conditions. In addition to

information from questionnaires completed by the volunteers, medical data were gathered on

some ’flights’; these included ‘passenger’ blood pressures and blood samples for testing for

increased susceptibility to infections and deep vein thrombosis. Information from 35 simulated

flights was complemented with questionnaire-based data gathered by the team on real flights.


A key feature of the project has been the selection of volunteers to represent, as far as possible,

the full spectrum of commercial aircraft passengers in terms of gender and age. The sample also

included risk-group volunteers with either cardiovascular or respiratory symptoms. The data were

used to develop guidance for relevant stakeholders which will help them to address concerns

about the impacts of cabin environment on passenger health. The ICE Consortium has worked

hand in hand with ASD-STAN to use the new data and findings obtained during the ICE project to

develop a European pre-Standard relating to commercial aircraft cabin environments.

The draft of the pre-Standard (prEN 4666) contains the first scientifically (health) based standard

for cabin pressure appropriate to the spectrum of the flying public. In addition, it addresses other

parameters not addressed previously in the European Cabin Air Quality pre-Standard prEN 4618,

such as ambient air temperature, humidity, air flow, and noise. These are considered individually

–as well as in combination – with all based on optimised health and comfort criteria. The draft

thus not only address levels for safety, but also for comfort and health.

The participating research consortium presented their findings at the ICE international conference

in Munich during 9th – 10th March 2009 (www.ice-project.eu). Some of the key findings presented

were:

• There was no consistent relationship between measured passenger physiological

symptoms and cabin air pressure altitude (up to 8000 ft) – hence provide environment not

more than 8000 ft;

• Cabin air temperature to be between 21 0C and 25 0C (optimum 23 0C) and relative

humidity to be between 25 – 40% (if technical constraints permit) – and both can be varied

independently to each other;

• Within a cabin ventilation rate of 15 to 20 cfm, the recirculation percentage can be varied

between 0 to 50%;

Overall, the ICE project indicated that flying in current commercial aircraft environments poses, in

general, no significant health risk for passengers.

http://www.ice-project.eu)


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Contents

Description of the project 5

Work Packages 7 Work Package 1 – Knowledge and Stakeholder Integration 7 Work Package 2 and 3 – Campaign Design and Flight Campaign – ACE, FTF and in-flight) 10 Work package 4 – Building the Engine Data 16 Work Package 5 – Human Impact and Optimisation 17 Work Package 6 – ICE Design Guides and Standards 22


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Description of the project

The overall conclusion of the now completed ICE (Ideal Cabin Environment) project showed that flying in current commercial aircraft environments poses, in general, no significant health risk for passengers.

This eight-nation research project was carried out within the European Commission’s 6th Framework Programme and was completed in March of this year after just over three years of extensive study. The overall aim of ICE was to provide airframers and airlines with step-change knowledge and innovations to address the concerns about the unknown combined effects of cabin environmental parameters, including for the first time cabin pressure, on the health of passengers in commercial aircraft.

ICE addressed the widespread concerns about the impact of flying on the health and well-being of passengers. Changing passenger demographics, the advent of ultra-long-haul services, and specific health issues such as deep vein thrombosis (DVT), had all combined to increase concerns. The key objectives of ICE were to determine health-based optimum levels of cabin environmental parameters and their synergistic effects on, amongst others, hypoxia (often considered the most serious single physical hazard) and possible links with DVT.

Nearly 1,500 volunteers took part in eight-hour ‘flights’ in simulated aircraft cabin facilities at the Fraunhofer Institute for Building Physics in Holzkirchen near Munich, Germany, and at the BRE Group’s Watford headquarters in the UK. A team of researchers, medical experts and cabin environment specialists investigated the effects on passengers of a range of cabin conditions including, for the first time, cabin pressure.

The tests simulated a long-haul flight experience with realistic cabin conditions. In addition to information from questionnaires completed by the volunteers, medical data were gathered on some ’flights’; these included ‘passenger’ blood pressures and blood samples for testing for increased susceptibility to infections and deep vein thrombosis. Information from 35 simulated flights was complemented with questionnaire-based data gathered by the team on real flights.

A key feature of the project has been the selection of volunteers to represent, as far as possible, the full spectrum of commercial aircraft passengers in terms of gender and age. The sample also included risk-group volunteers with either cardiovascular or respiratory symptoms. The data were used to develop guidance for relevant stakeholders which will help them to address concerns about the impacts of cabin environment on passenger health. The ICE Consortium has worked hand in hand with ASD-STAN to use the new data and findings obtained during the ICE project to develop a European pre-Standard relating to commercial aircraft cabin environments.

The draft of the pre-Standard (prEN 4666) contains the first scientifically (health) based standard for cabin pressure appropriate to the spectrum of the flying public. In addition, it addresses other parameters not addressed previously in the European Cabin Air Quality pre-Standard prEN 4618, such as ambient air temperature, humidity, air flow, and noise. These are considered individually –as well as in combination – with all based on optimised health and comfort criteria. The draft thus not only addresses levels for safety, but also for comfort and health.

The participating research consortium presented their findings at the ICE international conference in Munich during 9th – 10th March 2009 (www.ice-project.eu). Some of the key findings presented were:

• There was no consistent relationship between measured passenger physiological symptoms and cabin air pressure altitude (up to 8000 ft) – hence provide environment not more than 8000 ft;

• Cabin air temperature to be between 21 0C and 25 0C (optimum 23 0C) and relative humidity to be between 25 – 40% (if technical constraints permit) – and both can be varied independently to each other;

• Within a cabin ventilation rate of 15 to 20 cfm, the recirculation percentage can be varied between 0 to 50%.

http://www.ice-project.eu)


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Overall, the ICE project indicated that flying in current commercial aircraft environments poses, in general, no significant health risk for passengers.


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Work Packages

Work Package 1 – Knowledge and Stakeholder Integration

(led by Avitronics, Greece)

The key objective of ICE was to provide airframers/airlines with step-change knowledge and innovations to address the concerns about cabin environmental parameters on the health of passengers in commercial aircraft. In order to achieve this scope a comprehensive review of current knowledge of the cabin environment was carried out, and results from relevant FP5-based projects were incorporated, to build on the knowledge gained in previous research. Furthermore, stakeholder workshops were organized in order to mobilise all of those interests and actors – nowadays known as ‘stakeholders’ – behind the task of producing the flying experience of the future and competitive products.

A comprehensive review of current knowledge of the cabin environment was carried out, and results from relevant FP5-based projects were incorporated, to build on the knowledge gained in previous research. The aim was to collate information on cabin environment parameters, in order to identify those parameters most likely to be of importance to the health (psychological and physiological well-being) of passengers).

Data from FP5 projects included in this deliverable includes results from the projects themselves and from literature reviews undertaken as part of those projects. Outputs from CabinAir, FACE, HEACE, ASICA and IDEA-PACI are included.

As far it concerns the workshop, it was hosted by IBP at their site in Holzkirchen, Germany. The workshop included a visit to the flight test facility (FTF).

The following stakeholder groups were represented.

• Airframers

• Manufacturers/suppliers

• Airlines

• Crew

• Regulatory

• Research/academic

• Aviation health

The delegates took part in discussion groups, to talk about the following topics.

• What are the target groups for dissemination?

• What would be the most effective means for dissemination?

• What are the research questions that should be addressed in the analysis?


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• What is your vision for the future of aviation health research?

The stakeholders indicated that there were three separate and identifiable stakeholder groups that any dissemination strategy needed to address, namely:

• Cabin occupants (passengers and cabin crew);

• Direct providers (airlines, health practitioners, and lobbying/pressure groups);

• Indirect providers (airframers, system manufacturers, regulators, and policy makers).

Their specific topics of interest were identified as follows:

• Air ventilation and circulation;

• Deep vein thrombosis (mainly through immobility in long-haul flights);

• Fitness to fly of passengers;

• Cabin temperature;

• The low relative humidity within the cabin;

• Oxygen levels within the cabin;

• Noise and vibration.

In addition, they identified issues outside of ICE but relevant in framing any guidance, namely:

• Spread of infection;

• Jet lag;

• Ingress of toxic contaminants through, say, the pyrolysis of engine oils and lubricants;

• Cosmic radiation;

• Anxiety and fear of flying.

Their preferred methods of dissemination depended on the stakeholder group. For cabin occupants, theirs were:

• Newspapers;

• General interest magazines;

• Professional trade magazines;

• Airline in-flight magazines;

• Passenger information sheets;

• Radio and television;

• Internet web sites.


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For ‘direct providers’, their preferred methods were:

• Journal publications;

• Medical lectures and ‘continuing professional development’ courses;

• Specialist workshops, meetings, and conferences;

• Publications from professional bodies;

• Website links to and from aviation, and aviation-health related sites;

• Radio and television.

For ‘indirect providers’, their preferred methods were:

• Regulations, Standards, and guidelines;

• Journal publications;

• Specialist workshops, meetings, and conferences;

• Publications from professional bodies;

• Website links to and from aviation, and aviation-health related sites.

All stakeholders were kept informed of project developments through the regular press releases, general journal articles, ad-hoc presentations at various meetings and conferences, and through the dedicated ICE public website http://www.ice-project.eu/

http://www.ice-project.eu/


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Work Package 2 and 3 – Campaign Design and Flight Campaign – ACE, FTF and in-flight)

(Led by Fraunhfoer IBP, Germany)

Summary

This paper summarizes the ICE test campaign. Focusing on the tests at Fraunhofers Flight Test Facility achieved climate conditions are reported and the impact of the cabin climate on selected comfort votes given by subjects has been analyzed.

1 Description of Tests

The impacts of varying levels of the environmental parameters pressure, humidity, temperature, noise and air supply rates on subjects were investigated using unique large-scale aircraft cabin environment facilities to determine optimum individual and combined levels for human well-being. While a study focusing on ventilation rates was performed in the Aircraft Cabin Environment (ACE) rig at the Building Research Establishment Ltd. (BRE) in Watford, UK a large part of the Ideal Cabin Environment (ICE) test campaign was conducted at the Flight Test Facility (FTF) at the Fraunhofer Institute for Building Physics (IBP) in Holzkirchen, Germany. Finally two real flight tests were performed to compare the simulator studies against reality.

The remainder of this paper will focus on the framework of the study performed in the FTF. Details of the whole project will be reported during the ICE International Conference in Munich, Germany (9./10.3.2009) together with other project outcomes.

1.1 The Flight Test Facility

The FTF consists of a 30 m long pressure vessel which holds the first 16 m of a complete wide-body aircraft (see Figure 1). The interior of the aircraft was maintained to give subjects a realistic impression of flying (see Figure 2) while the main environmental parameters can be varied and controlled: air pressure, air and fuselage temperature, relative humidity, noise and vibration, lighting, ventilation rate, etc. [1].

Figure 1: Front segment of an A310-200 inside the pressure vessel.

Figure 2: Interior of the FTF aircraft cabin.

1.2 Test Design


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To investigate the impact of aircraft cabin environments on the passengers’ well-being a subject study has been performed varying cabin pressure, relative humidity, air temperature and noise level while other environmental parameters were kept constant.

The study at FTF consisted of 29 simulated 7h flights lasting from November 2006 to January 2007. For four of these flights subjects with slight pulmonary or cardiovascular diseases were acquired to examine the effects on passengers at-risk. To take the differences between exposition and the general state into account baselines of 30min before and after each simulated flight were introduced. Thus each test consisted of 30min pre-baseline, 30min take-off, 30min stabilization of environmental conditions, 5.5h cruise, 30min landing, and 30-min post-baseline, so that each test had a total duration of 8h (see Figure 3).

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Figure 3: Schedule of a simulated flight test.

During all baselines the physical parameters were controlled to the same level, while the levels during the simulated flights differed. The levels were chosen according to sensible values for an aircraft cabin environment: ambient, 875 hPa, 812 hPa, and 753 hPa for barometric pressure; 10% (very low but usual in aircraft cabins), 25% (rather low, but possibly achievable within aircraft cabins), and 40% (medium but very high for aircraft cabins) for relative humidity; 21°C, 23°C, and 25°C for temperature (all near the expected thermal comfort region); 55.1 dB(A) (background noise with just HVAC systems running), 64 dB(A) (quite high, but hardly achievable for aircraft and still a sensible aircraft sound), 69 dB(A), and 74 dB(A) (usual for aircraft) as noise levels. A summary of target levels is given in Table 1.

Table 1: Target levels of environmental variables. Target levels during baselines are bolded.

Variable Pressure Relative Humidity Temperature Sound Pressure Level Unit [hPa] [%] [°C] [dB(A)] Level 1 ambient 10 21 HVAC Level 2 875 25 23 64 Level 3 812 40 25 69 Level 4 753 74

1.3 Subjects

For each test in the FTF test rig 40 healthy subjects were selected. The flying public was addressed by accounting for three different age groups and gender according to the subject profile in Table 2.


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Table 2: Target subject profile with respect to gender and age.

Age 18 – 34 35 – 49 50+ Male 6 or 7 7 or 6 7 Female 7 or 6 6 or 7 7 For four tests a sub-sample of 20 persons with diseases of particular interest was selected to achieve equal numbers of persons with a cardiovascular disease (New York Heart Association (NYHA) class 2 heart failure) or a pulmonary disease (chronic obstructive pulmonary disease (COPD) patients with Medical Research Council (MRC) Dyspnoea grade 2). The remainder of 20 subjects represented the healthy public (referred to as having a normal health status). These tests received approval of both, the research ethics committee of the Royal Free Hospital & Medical School in London, UK and ethics committee of the Ärztekammer Nordrhein in Düsseldorf, Germany. All subjects gave their written consent before participating in this research.

The subjects were allowed to move inside the cabin and to spend their time on their own way apart from the filling out of questionnaires. Meals and drinks were provided on a regular basis, lavatories were onboard.

1.4 Questionnaires

Two Questionnaires with approximately 100 items each have been developed and supervised under responsibility of the Unit of Human Factors and Ergonomics, Medical University of Vienna. They were presented on 4- or 7-point scales via PDAs which have been explained to the subjects during the distribution of the first questionnaire. The items of the first questionnaire considered the subjects’ state of comfort, mood, symptoms and behavior. It was distributed five times during each test: in the baselines and at 90 min, 240 min and 390 min after start of each test. The second questionnaire asked for the subjects’ personal characteristics, their health status, general well-being and sensitivity to certain environmental situations. This questionnaire was handed out right after the questionnaire at 240 min after start of each test.

1.5 Environmental Measures

The physical variables have been measured in one minute intervals throughout each test. The barometric pressure has been monitored at one location inside the cabin. Relative humidity was measured using capacitive sensors in each row inside the cabin at 1.1 m height. Air temperature has been averaged over measurements with dry bulb thermometers in 0.1 m, 0.6 m and 1.1 m height at every second seat. Their mean levels and standard deviations during cruise phase are reported in Table 3 to Table 5.

Table 3: Pressure levels during cruise phase.

Pressure levels in hPa target mean stdv.

ambient 938.9 0.9 875 875.2 0.8 812 813.9 0.8 753 753.7 1.2

Table 4: Relative humidity levels during cruise phase.

Relative humidity levels in % target mean stdv.

40 40.93 1.60 25 24.10 1.20 10 10.93 1.54

Table 5: Temperature levels during cruise phase.

Temperature levels in °C target mean stdv.

25 24.29 0.58 23 22.49 0.75 21 20.78 0.92


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The background noise consisted of in-flight recordings of an A320-flight including take-off and landing. These sounds were reproduced by diverse loudspeakers distributed along the cabin in the ceiling and dado panels. Its levels have been calibrated by University of Oldenburg, Institute of Physics inside the empty cabin with HAVC systems running before performing the study with microphones positioned 0.65 m above each seat and ca. 0.15 m in front of the backrest. The levels reached are reported in Table 6.

Vibrations are induced via the same playback system as background noises. They are generated by shakers mounted underneath each seat. In this study the vibrations were changed linearly with the background noise and calibrated at the transition point of the seat frame and seat rail. Error! Reference source not found. depicts the weighted total accelerations.

Table 6: Background noise levels.

Background noise levels in dB(A)

target mean stdv. 74 73.8 1.1 69 68.8 1.1 64 63.8 1.1

HVAC systems 55.1 2.5 Table 7: Background vibration levels.

Background vibration levels in dB

target mean stdv. 84 83.8 4.2 79 78.8 4.2 74 73.8 4.2

HVAC systems 77.2 1.2 Besides diverse VOCs the following compounds have been measured by EADS Innovation Works in 1 min intervals throughout each test: CO2 with FT-IR with 5 m gas cell, Ozone with UV Photometry, and TVOC with an online FID. Furthermore particulates (PM10 and PM2) have been measured by IBP throughout each test in 1.1 m height at two locations inside the cabin with Grimm Portable Dust Monitors. Levels of airborne bacteria and fungi were investigated by IBP’s microbiologists. These have been monitored with an Aerosol Sampler AirPort MD8 with gelatin membrane filters at certain point in a height of 0.8 m at two locations inside the cabin. Subsequently cultivation methods have been used to analyze the amount of colony forming units (CFU). A more detailed discussion of measurement results can be found in [2].


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1.6 Physiological Measures

Before and after each of the tests with subjects with slight pulmonary and cardiovascular diseases a mini-lung function test with Clement Clarke spirometers was performed and blood samples were taken by investigators of the University College London. The latter ones were drawn into Vacutainer blood collecting systems prepared with Sodium Citrate and EDTA.

A notebook-based modified Békésy method was used by researchers from University of Oldenburg, Institute of Physics to perform an audiogram with a subset of six subjects before and after 15 tests without subjects at-risk.

During the questionnaire phases of each test investigators of the Medical University Vienna took the subjects’ blood pressure with Tensoval ambulatory blood pressure units by Hartmann. Additionally each subject wore an electrocardiogram recorder by Medilog TOM GmbH throughout the test logging signals for the analysis of heart rate, heart rate variability, respiratory frequency and electrodermal activity.

To measure the motor activity investigators of the German Aerospace Center, Institute of Aerospace Medicine equipped each of the subjects with miniature apparatuses “BMD-Actometer” (company Gefatec GmbH, Tiefenbach, Germany) at their left thigh. Furthermore each subject wore a finger pulse oximeter (Nonin’s WristOx® 3100) throughout the whole test.

2 Results

First observations after analyzing comfort votes with respect to the questions regarding temperature, humidity and sound are reported. The answers of those flights have been considered, which could be compared across all four environmental variables (pressure, temperature, humidity and noise). While grouping votes according to the target levels of the associated environmental variable the other environmental parameters vary freely. E.g. when considering thermal comfort votes these have been grouped for temperature levels, while pressure, relative humidity and sound pressure level vary.

As expected temperatures of 21°C are voted slightly “too cold”, whereas 23°C are voted comfortable with a tendency to the “too cold” and 25°C comfortable with a tendency to the “too warm” side. This pattern of voting temperatures in similar environments is well known, see for example [3]. Comfort votes with respect to humidity are mainly slightly “too dry”, which was expected at least for the 10% relative humidity level. Even at 40% relative humidity the subjects voted the environment slightly “too dry”. Similar findings were reported in [4]. Generally the human being lacks of an organ to sense humidity directly, so they measured several physiological factors to get a more complete picture of this issue. However, in their study subjects voted all relative humidity conditions (5% to 35% at 22°C) slightly dry with the conditions 5% and 15% significantly dryer than 25% and 35%. The sound pressure level was voted “too loud” for both conditions, 64 dB(A) and 74 db(A). The higher sound pressure level was voted worse than the lower one, as has been hypothesized. This concurs with findings of [5], who investigated background noise levels of 35 dB(A), 60 dB(A) and 75 db(A) at different temperatures.

However, apart from these first observations illustrative data analysis will be presented at the ICE international aviation conference which concludes this project. Overall comfort votes vary as expected within the selected environmental parameter ranges. Their variance is quite high, which lies in the nature of subject votes. This has been challenged by a very large sample which is unique of its kind. It has been used for enhanced modeling purposes to provide stakeholders, such as airframers and public bodies, with


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tools and recommendations for the design and assessment of aircraft cabin environments. Furthermore the data has been analyzed to find answers on public concerns, such as the risk of developing deep vein thrombosis, based on health-related data of a very broad spectrum of today’s passengers, which will be reported in associated contributions at the ICE international aviation conference.

References

[1] Mayer E, Grün G, Hellwig R, Holm A. The New Pressurised Fraunhofer Flight Test Facility Offered to the Scientific Cabin Environment Network. Proceedings of 1st CEAS European Air and Space Conference, Berlin, Germany, CEAS-2007-468, pp. 889-893, 2007.

[2] Grün G, Holm A, Luks N, Malone-Lee J, Trimmel M, Schreiber R, Mellert V, Kos J, Hofbauer W. Impact of Cabin Pressure on Aspects of the Well-Being of Aircraft Passengers – A Laboratory Study. Proceedings of 26th ICAS Congress, Anchorage, Alaska, USA, submitted.

[3] Strøm-Tejsen P, Zukowska D, Jama A, Wyon DP. Assessment of the thermal environment in a simulated aircraft cabin using thermal manikin exposure. Proceedings of Roomvent 2007, Helsinki, Finland, paper ID 1198, 2007.

[4] Wyon DP, Fang L, Meyer HW, Sundell J, Weirsøe CG, Sederberg-Olsen N, Tsutsumi H, Agner T, Fanger PO. Limiting Criteria for human exposure to low humidity indoors. Proceedings of Indoor Air 2002, Monterey, California, USA, pp. 400-405, 2002.

[5] Pellerin N, Candas V. Effects of steady-state noise and temperature conditions on environmental perception and acceptability. Indoor Air, 14, pp. 129-136, 2004


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Work package 4 – Building the Engine Data

(Led by University of Vienna)

Unavailable – preparing for publication


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Work Package 5 – Human Impact and Optimisation

(Led by University of NLR, Netherlands)

Summary

An informed judgement on the health and well-being effects of long-haul flight is contingent on well controlled experiments with substantial samples, as may be observed in aircraft cabin environment simulators. Two such simulators, both based on wide-bodied aircraft cabins, provided the facilities for a vast set of experiments as performed in the frame of the European research project ICE (Ideal Cabin Environment). However, the many measured variables of cabin conditions and subjects’ responses in these experiments make it difficult to assess the key effects and the precise relationships that exist among the many variables. Moreover, to use these relationships for predictions of effects of aircraft cabin environment on passenger health and well-being, mathematical expressions of these relationships are needed. Therefore, in the same European research project, mathematical models were developed for the health and well-being of aircraft passengers under varying cabin environmental conditions.

The development of the models is based on the data from the experiments. From the measurements in the experiments of the ICE project a massive data set was obtained, containing the values of hundreds of variables for each of the approximately 1400 subjects. This large data set has been locked and stored, and was then further analyzed, checked and filtered into a more compact data set comprising only the key information on the experimental cabin conditions and the associated health and well-being effects. This compact data set, the so-called model-sheet, was then used to develop statistically based multi-variate regression type models of all the significant relations between the cabin conditions and the health and well-being effects that could be identified from the experimental data.

This paper presents a brief description of the models of aircraft passenger health and well-being that weredeveloped. The data that is used in the development of these models is described in some detail, as well as the modelling procedure and the resulting models. The models allow for easy prediction of the effects of the aircraft cabin environment on each of the many different health and well-being variables, as such enabling efficient cabin design effect studies with respect to the passenger health and well-being.

Introduction

Widespread concerns about the impact of aircraft cabin environment on the health and well-being of passengers in commercial aircraft have received increasing attention in the past decade. Changing passenger demographics, the advent of ultra-long-haul services, and specific assumed air travel related health issues such as deep vein thrombosis (DVT) and severe acute respiratory syndrome (SARS) have all combined to these increased concerns [Mangili et al., 2005; Nicholson et al., 2003].

More specifically, passenger comfort was shown to be affected by humidity, pressure, temperature and noise in the aircraft cabin [Nicholson et al., 2003]. Muhm and others [Muhm et al., 2007] reported a study on healthy volunteers using a hypobaric chamber. At pressures equivalent to 8000ft altitude, SO2 fell to between 93% and 91%. This was shown to contribute to a feeling of discomfort in un-acclimatised participants after between three and nine hours.


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An informed judgement on the health and well-being effects of long-haul flight is contingent on well controlled experiments with substantial samples, as may be observed in aircraft cabin environment simulators. Two such simulators, both based on wide-bodied aircraft cabins, provided the facilities for these experiments as performed in the frame of the European research project ICE [ICE project, 2005]. The resulting experimental data is used for detailed assessments of specific health effects, e.g. [ICE Consortium, 2009]. However, the many measured variables of cabin conditions and subjects’ responses in these experiments make it difficult to assess the key effects and the precise relationships that exist among the many variables. Moreover, to use these relationships for predictions of effects of aircraft cabin environment on passenger health and well-being, mathematical expressions of these relationships are needed. Therefore, in the same European research project, mathematical models were developed for the health and well-being of aircraft passengers under varying cabin environmental conditions.

This paper presents a brief description of the models of aircraft passenger health and well-being that were

developed. The data that is used in the development of these models is described in some detail, as well as the modelling procedure and the resulting models. The resulting models allow for easy prediction of the effects of the aircraft cabin environment on each of the many different health and well-being variables, as such enabling efficient cabin design effect studies, and possibly cabin optimisations, with respect to the passenger health and well-being.

The experiments

The impacts of varying levels of the aircraft cabin parameters pressure, humidity, temperature, noise and air supply rates on subjects’ health and well-being were investigated using two state-of-the-art large-scale aircraft cabin environment simulation facilities. One facility, the Flight Test Facility (FTF) at the Fraunhofer Institute for Building Physics (IBP) in Holzkirchen, Germany [Mayer et al., 2007], focused on the effects of the pressure, humidity, temperature and noise in the aircraft cabin. The other facility, the Aircraft Cabin Environment (ACE) rig at the Building Research Establishment Ltd. (BRE) in Watford, UK [Grün et al., 2008], focused on the effects of ventilation and recirculation rates of the cabin air flow. In each of the FTF and ACE flight tests approximately 40 subjects participated, yielding in total more than 1400 subjects. The subjects for the FTF and ACE tests were carefully selected according to sex and age profiles.

For model validation, a series of measurements were also carried out on passengers during regular commercial flights. Measurements on passengers on board these flights, co-operating voluntarily, were taken by a questionnaire survey, complemented by a limited number of basic measurements of the cabin conditions. Passenger responses to the changes in the aircraft cabin environment were assessed by various cardiovascular measurements, such as ECG and finger-pulse oxymetry, and by two different questionnaires, assessing passengers' state of comfort, mood, symptoms, behaviour, and personal characteristics, health status, general well-being, sensitivity, respectively. More detail about the measured variables is given in [Grün et al., 2008].

The models

Different approaches have been followed in the developments of the models. The first approach focused on generic methods, in this case based on statistical analyses, regression methods and neural networks that were applied to the data from the experiments. Another approach focused on known physical and


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physiological relationships between the cabin environment and its impact on the occupants, and has exploited the experimental data to further enhance these relationships on specific aspects. Both model types have been implemented in dedicated evaluation functions. This paper focuses on the first type of models that are based on the generic modelling methods.

The models provide a representation of the dependencies of a number of aspects of health and well-being of aircraft passengers on aircraft cabin conditions. These aspects of health and well-being cover a number of physiological quantities, such as heart rate, blood pressure and blood oxygen saturation, and a number of psychological quantities, such as aircraft passenger comfort perception measured by questionnaires.

The dependencies of the aspects of health and well-being on aircraft cabin conditions, such as pressure, temperature and humidity, have been assessed in detail in the ICE experiments. The results that were obtained from these experiments were used to build and validate the models. The models allow for computational evaluation of the effects on aircraft passenger health and well-being due to variations in the aircraft cabin conditions. As such the models can be used to identify those aircraft cabin conditions for which the best results for passenger health and well-being can be expected.

Model predictions

The generic models have been used to investigate the effects of the aircraft cabin on the passengers’ health and well-being. These investigations yield information that can be used to optimise the aircraft cabin for certain aspects of the passengers’ health and well-being. Because of the extensive number of input and output variables of the seatbased generic models, the scope of this investigation was limited to the effects of the main physical cabin and flight conditions on the primary output variables as predicted by the models.

The effects of the variation of each of the above given single physical cabin and flight conditions input variables on each of the primary output variables was evaluated with the seat-based generic models. The change of the output variable relative to its value in the mean comfort condition is calculated, and normalised with the possible range of values of that output variable as found from the evaluation with the FTF data input set described above. These relative change values for each output variable can be considered as the global sensitivities of the model for each of the single physical cabin and flight conditions input variables and are presented in the figure 1 below.

Typically, the drop of oxygen saturation (SpO2_spot) at low cabin pressure (press. - lower bound) can be clearly observed, as expected. In addition, the mean temperature comfort score (MEAN_C_Temp) also clearly drops when cabin air temperature (temp. - lower bound) is at the lower limit level.

Conclusions

The impact of the cabin environment on passengers’ health and well-being has got increasing attention in the past decade. There is a growing need to improve the passengers comfort onboard aircraft further. The ICE experiments have resulted in an extensive data set on health and well-being of passengers. To evaluate the impact of technical and/or behavioural changes of the cabin environment and its passengers on the passengers’ health and well-being, prediction of the key indicators of passengers’ health and well-being as a function of key cabin environmental variables is needed.


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The models developed within the ICE project provide a representation of the dependencies of various physiological and psychological aspects of aircraft passengers on aircraft cabin conditions, flight characteristics and passenger characteristics, including behaviour. The software implementation of the models allows for quick computational evaluation of this representation.

The model has been applied in several cases that assess the effects of the cabin conditions on the health and well being of aircraft passengers in order to prepare for the technical and behavioural recommendations for the various stakeholders.


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Figure 1: Model sensitivities: relative responses (in %) of all primary output variables evaluated with the model and resulting from the above given variations of the input variables. Note, for example, the clear dependence of temperature comfort (Mean_C_Temp) on cabin temperature (temp. – lower/upper bound). References [Mangili et al., 2005] Mangili A., Gendreau M.A., Transmission of infectious diseases during commercial air travel, The Lancet, 12 March 2005; 365(9463), pp. 989-996.

[Nicholson et al., 2003] Nicholson A.N., Cummin A.R., Giangrande P.L., The airline passenger: current medical issues. Travel Med. Infect. Dis. 2003; 1(2), pp. 94-102.

[Muhm et al., 2007] Muhm J.M., Rock P.B., McMullin D.L., Jones S.P., Lu I.L., Eilers K.D., Effect of aircraft cabin altitude on passenger discomfort. N. Engl. J. Med. 2007; 357(1), pp. 18-27.

[ICE project, 2005] http://www.ice-project.eu (accessed January 2009).

[ICE Consortium, 2009] Ideal Cabin Environment (ICE) Research Consortium of the European Community 6th Framework Programme, A study of the health effects of airline passenger cabin environments in simulated 8-hour flights. N. Engl. J. Med. 2009; submitted.

[Mayer et al. 2007] Mayer E., Grün G., Hellwig R., Holm A., The New Pressurised Fraunhofer Flight Test

Facility Offered to the Scientific Cabin Environment Network. Proceedings of 1st CEAS European Air and Space Conference, Berlin, Germany, CEAS-2007-468, pp. 889-893, 2007.

[Grün et al., 2008] Grün G., Holm A.H., Luks N., Malone-Lee J., Trimmel M., Schreiber R., Mellert V., Kos J., Hofbauer W., Impact of cabin pressure on aspects of the well-being of aircraft passengers – a laboratory study.

Proceedings of 26th ICAS Congress, Anchorage, Alaska, USA, 2008.

http://www.ice-project.eu

Ideal Cabin Environment (ICE) Project

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Work Package 6 – ICE Design Guides and Standards

Introduction

After EN 4618 the new preStandard (prEN 4666) is the first of its kind for aeronautical air quality, comfort, now including cabin air pressure. It is complementary to EN 4618, identifying amendments and additional requirements. It is intended for use in design, manufacturing, maintenance and normal operation of commercial aircraft. The standard is performance based. This means that only parameters of direct effect on safety, health and comfort of aircraft occupants are considered. This approach enables future proofing of design and development of innovative solutions as well as enabling existing technologies to be used.

Scope of the prEN 4666

The standard specifies requirements and determination methods for newly certificated commercial civil passenger aircraft programmes regarding integrated air quality parameters and cabin air pressure. It may also apply to current production aircraft if it does not carry significant burden, i.e. if it can be shown to be technically feasible and economically justifiable. It covers the period for each flight when the first crewmember enters the aircraft until the disembarkation of the last crewmember. The standard covers refined or new data for Pressure Conditions (air pressure rate of change, absolute cabin air pressure), Thermal Conditions (air temperature, surface temperature, draught), Humidity Conditions, Noise and Vibration as well as Combined Effects.

Standardisation Procedure

In Europe, ASD-STAN (http://www.asd-stan.org) is taking control of establishing, developing and maintaining standards requested by the European aerospace industry. ASD-STAN was established in October 2005 and changed its name from the former AECMA-STAN. The process for standardisation is in agreement with the European Committee for Standardization (CEN).

Reference Information on prEN 4666 Title: “Aerospace Series - Aircraft integrated air quality and pressure

standards, criteria and determination methods” Edition: prEN 4666:2009

http://www.asd-stan.org

ideal cabin environment (ice) project · • cabin occupants (passengers and cabin crew); •...

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