Aircraft Cabin Air

The air you breathe on an aircraft may not be as good as you had hoped for. Coming to this page, you probably know already. However, if it is all new to you, read my German Memo or watch this Video in English.

CabinAir

Abstract

A detailed look at the design of jet engines with their bearings, lubrication and sealing reveals that jet engines leak small amounts of oil by design. This oil gets into the engine compressor and the bleed air. Almost all passenger jet aircraft today use this potentially contaminated bleed air for cabin ventilation.

Own Contributions

Papers, Presentations, Memos
Videos

Student Contributions
Media Coverage (selected)
More News
Action

CO Detectors
Breathing Masks

Links
Films

all related to Aircraft Cabin Air Quality / Contamination.

On another page:

Proceedings of the Aircraft Cabin Air Conferences

Reach this page with: http://CabinAir.ProfScholz.de
See also:

Own Contributions

Book, Papers, Presentations, Memos

Book Cover of: Aircraft Cabin Air Contamination

Book to be published in 2026: D. Scholz: Aircraft Cabin Air Contamination – An Engineering Perspective. More: Flyer and www.buchhandel.de or www.amazon.de.

Author Title Type of Work Delivered No of Pages Occasion / Purpose Abstract PURL/DOI Full Text Size

Dieter Scholz englisch Aircraft Cabin Air Contamination – From Technical Basics to Legal Disputes Presentation 25.10.25 58 Gründungsversammlung des
"Förderverein ansTageslicht.de"
Alfred Schnittke Akademie,
Max-Brauer Allee 24, Hamburg https://doi.org/10.48441/4427.2930 3.9M

Dieter Scholz englisch Litigation Due to Aircraft Cabin Air Contamination – Fundamentals and Current State Presentation 23.09.25 58 Deutscher Luft- und Raumfahrtkongress 2025,
Augsburg (Germany), 23.-25.09.2025 Similar presentation as the one from 25.10.2025.

Dieter Scholz englisch Technical Analysis of the Accident: Swiss Flight LX1885 with an Airbus A220 – From Uncontained Engine Failure via Smoke on Board, A Dead Flight Attendant to Alleged Cover up at Austrian's Federal Safety Investigation Authority (SUB) Poster 23.09.25 1 Deutscher Luft- und Raumfahrtkongress 2025,
Augsburg (Germany), 23.-25.09.2025 https://doi.org/10.48441/4427.2885 398K

Dieter Scholz deutsch Neue Forschung zur Kontamination von Kabinenluft Magazin-Artikel 23.09.23 4 Gastbeitrag VC-Info (online)
Gastbeitrag VC-Info 3/2023, S. 18) https://doi.org/10.48441/4427.1110
1.1M

Dieter Scholz deutsch Flughafen Hamburg, Airbus A321, Abbruch eines Fluges kurz nach dem Start, Kabinenluftkontamination Press Release 06.07.23 7 News, Hintergrund und Kommentar https://purl.org/aero/PR2023-07-06
547K

Dieter Scholz New
englisch Aircraft Cabin Air and Engine Oil – Engineering Aspects Presentation 27.06.23 36 International Aircraft Cabin Air Conference 2023
Online, 27 - 29 June 2023 https://purl.org/cabinair/GCAQE2023
2.5M

Dieter Scholz deutsch Forschung soll Hinweise geben zur Kontamination der Kabinenluft von Flugzeugen – Agentur der Europäischen Union für Flugsicherheit (EASA) Press Release 30.01.23 8 State of the art after the EASA Workshop in Cologne, 17.-18.01.2023 https://purl.org/aero/PR2023-01-30
409K

Dieter Scholz englisch Routes of Aircraft Cabin Air Contamination from Engine Oil, Hydraulic and Deicing Fluid Journal Paper 01.03.22 18 INCAS BULLETIN
Volume 14, Issue 1 / 2022, pp. 153 – 170 --- https://doi.org/10.13111/2066-8201.2022.14.1.13 3.3M

Judith Anderson, Dieter Scholz englisch Oil Fumes, Flight Safety, and the NTSB Journal Paper 10.12.21 20 Aerospace 2021, vol. 8, no. 12, art. 389, Special Issue "Aircraft Design" (SI-3/2021) --- https://doi.org/10.3390/aerospace8120389 12M

Dieter Scholz Agence Nationale de Sécurité Sanitaire (ANSES) – Hearing on the Operation of Air Conditioning in Aircraft Cabins and the Associated Air Quality Presentation 08.07.21 75 ANSES Investigation on "Air Quality in Aircraft and Health Effects on Aircrew"
Hearing Prof. Scholz, Online, 2021-07-08 https://purl.org/cabinair/ANSES2021
4.5M

Dieter Scholz deutsch Größte Konferenz über kontaminierte Luft in Flugzeugen: Zapfluftfilter und -sensoren müssen dringend in Passagierflugzeugen installiert werden Press Release 25.03.21 6 Report about the International Aircraft Cabin Air Conference 2021 --- 1.0M

Dieter Scholz englisch Aircraft Cabin Air and Engine Oil – Routes of Contamination Conference Paper 15.03.21 22 International Aircraft Cabin Air Conference 2021
Online, 15 - 18 March 2021 https://purl.org/cabinair/GCAQE2021
4.3M

Dieter Scholz englisch Aircraft Cabin Air and Engine Oil – An Engineering Update Presentation 15.03.21 42 International Aircraft Cabin Air Conference 2021
Online, 15 - 18 March 2021 https://purl.org/cabinair/GCAQE2021
2.4M

Dieter Scholz englisch Contaminated Aircraft Cabin Air - An Aeronautical Engineering Perspective Presentation 18.12.20 22 Press Meeting 10 Years German Wings "Cabin Air Contamination Event" (CACE): 2010-12-19 Online, HAW Hamburg, 2020-12-18 --- https://purl.org/cabinair/HAW2020 1.4M

Dieter Scholz deutsch Lufthansa-Rettung: Es geht nicht nur um CO2 --- Spezifische Anforderungen and die Lufthansa auch zum Thema "Kontaminierte Kabinenluft"! Offene E-Mail 13.05.20 2 Unterstützung aus dem Bereich der Technik für Sven-Christian Kindler (MdB) and Katharina Dröge (MdB) --- https://purl.org/cabinair/e2020-05-13 176K

Dieter Scholz englisch Lufthansa rescue: It's not just about CO2 --- Specific demands on Lufthansa also on the subject of "contaminated cabin air"! Open E-Mail 13.05.20 2 Technical support for Sven-Christian Kindler (MdB) and Katharina Dröge (MdB) --- --- 171K

Dieter Scholz englisch Congress on Poisoned Aircraft Cabin Air - First Solutions to the Problem Become Visible Press Release 24.09.19 6 International Aircraft Cabin Air Conference 2019
Summary of Technical Key Findings --- --- 577K

Dieter Scholz Cabin Air Contamination – A Summary of Engineering Arguments Presentation 18.09.19 35 International Aircraft Cabin Air Conference 2019
Imperial College London, 17 - 18 September 2019 --- https://purl.org/cabinair/GCAQE2019
2.2M

Dieter Scholz englisch Contaminated Aircraft Cabin Air - An Aeronautical Engineering Perspective Presentation 27.05.19 60 Meeting 2019, Association des Victimes du Syndrome Aérotoxique (AVSA), Paris CDG Airport, France, 27.05.2019 --- https://purl.org/cabinair/AVSA2019 3.2M

Dieter Scholz englisch A Quick Introduction to the Problem of Cabin Air Contamination Presentation 12.03.19 4 Deutscher Bundestag, Berlin, 12.03.2019 --- https://purl.org/cabinair/Parliament2019 373K

Dieter Scholz Technical Solutions to the Problem of Contaminated Cabin Air Presentation 05.09.18 76 Deutscher Luft- und Raumfahrtkongress 2018, Friedrichshafen (Germany), 04.-06.09.2018 https://publikationen.dglr.de/...
4.0M

Dieter Scholz englisch Jet Engines – Bearings, Seals and Oil Consumption Memo 02.04.18 22 Review to substantiate the calculation of the oil concentration in aircraft cabins https://doi.org/10.31224/osf.io/fk5dq 2.2M

Dieter Scholz Cabin Air Contamination - An Aeronautical Perspective Presentation 16.03.18 73 59. Kongress der Deutschen Gesellschaft für Pneumologie und Beatmungsmedizin e.V., Dresden (Germany), 16. März 2018 --- 5.0M

Dieter Scholz deutsch Belastete Kabinenluft in Flugzeugen - Flugzeugbau-Experte Dieter Scholz sieht Handlungsbedarf Interview 06.12.17 4 Hinweis: Dies ist eine etwas
vollständigere Version des Interviews
als im Themendienst der HAW Hamburg vom 03.04.2018
Streichungen der Pressestelle sind hervorgehoben. --- https://purl.org/aero/INT2017-12-17 501K

Dieter Scholz englisch Aircraft Cabin Air - Quality or Contamination? Presentation 20.11.17 48 Personalversammlung "Kabine"
Deutsche Lufthansa AG
Frankfurt, 20 November 2017 --- --- 4.1M

Dieter Scholz deutsch Die Luft in der Kabine von Passagierflugzeugen ist nicht so gut wie oft angenommen - Hintergründe, Lösungsmöglichkeiten und deren Umsetzung Memo 01.10.17 4 Populärwissenschaftliche Darstellung und Einführung --- https://purl.org/aero/M2017-10-01
https://doi.org/10.31224/osf.io/he59k englisch 224K

Dieter Scholz Aircraft Cabin Air and Engine Oil - An Engineering View Journal Paper 17.09.19 6 International Aircraft Cabin Air Conference 2017
Imperial College London, 19 - 20 September 2017 765K

Dieter Scholz englisch Aircraft Cabin Air and Engine Oil - An Engineering View Presentation 19.09.17 72 International Aircraft Cabin Air Conference 2017
Imperial College London, 19 - 20 September 2017 https://purl.org/cabinair/GCAQE2017
5.2M

Dieter Scholz englisch Aircraft Cabin Air and Engine Oil - A Systems Engineering View Presentation 27.04.17 75 Hamburg Aerospace Lecture Series (HALS)
DGLR, RAeS, VDI, ZAL, HAW Hamburg
together with VC and UFO
HAW Hamburg, 27 April 2017 6.9M

Dieter Scholz englisch Aircraft Cabin Air & Water Contamination/Quality – An Aircraft Systems Engineering Perspective Presentation 01.04.14 46 QCAQE – Global Cabin Air Quality Executive
7th ANNUAL FORUM
London, 31 March – 2 April 2014
Video Showing Contaminated Water on Aircraft (2020)
Background to: Contaminated Water on Aircraft (2020)
--- https://purl.org/cabinair/AirAndWater
---
https://purl.org/cabinair/WaterContamination

PDF:
37M

Presentations are based on one another - extended through the years; shortened for the audience and allocated time.

Videos

YouTube Playlist: Cabin Air (Uploads to YouTube by Prof. Scholz) Pin

YouTube Playlist: Cabin Air (Video LINKS)

englisch Presentation at the International Aircraft Cabin Air Conference 2019

englisch Presentation at the International Aircraft Cabin Air Conference 2017

deutsch Dieter Scholz im Interview bei:
ZDFzoom - Dicke Luft im Flieger (2017)
deutsch Dieter Scholz im Interview bei:
Deutschlandfunk Nova - Kabinenluft (2017)

Video: Dust in Aircraft Cabin Air.mp4 Picture: Dust in Aircraft Cabin Air.jpg

Student Contributions

Author	University	Title	Type of Work	Delivered	No of Pages	Full Text	Size	Persistent Identifier
Carlos L. S. Raposo	Universidade de Lisboa, Instituto Superior Técnico	Bioaerosol Transport and Sensor in Passenger Aircraft	Master Thesis	October 2022	123	download	12.2M	https://doi.org/10.5281/zenodo.7444209
Lukas Stichternath	HAW Hamburg	Pilot Measures against Cabin Air Contamination	Bachelor Thesis	03.02.2021	115		8.4M	https://doi.org/10.15488/11531
Dennis Tietke	HAW Hamburg	Oil Leakage Paths within Compressors of Jet Engines and Oil Concentration in Aircraft Cabin Air	Project	25.03.2020	36		7.9M	https://nbn-resolving.org/urn:nbn:de:gbv:18302-aero2020-03-25.017
Taner Ayan	HAW Hamburg	Analyse der Liegezeiten von Passagierflugzeugen nach Fume Events mittels Flugverfolgung	Projekt	15.01.2020	68		4.9M	https://nbn-resolving.org/urn:nbn:de:gbv:18302-aero2020-01-15.016
Sascha Max	Hochschule RheinMain (Lufthansa Technik)	Entwicklung eines Versuchsaufbaus zur Detektierung von Triebwerksöl und Enteisungsflüssigkeit im Bleedsystem	Vortrag zur Bachelorarbeit	14.11.2019	8		693K	https://purl.org/cabinair/MAX-2019
Ferrão, Mariana Baião	NOVA University Lisbon	Preliminary Analysis of Engine Bleed Air Oil Contamination with the Aerotracer® during Off-Wing Acceptance Testing and On-Wing Flights	Master Thesis	05.11.2019	98		2.8M	http://hdl.handle.net/10362/103150
Marcel Lakies	HAW Hamburg	Dynamic Cabin Air Contamination Calculation Theory	Project	01.03.2019	84		3.2M	https://doi.org/10.15488/4543
Viola Voth	TU Braunschweig	Analyse der Entstehungsmechanismen von Ölnebel in Flugzeugkabinen	Bachelorarbeit	17.07.2018	116		11M	https://purl.org/cabinair/VOTH-2018
Arie Adriaensen	Lund University	Competing Discourses in Aircraft Cabin Air Contamination: How to Define a Problem	Master Thesis	24.01.2017	127		2.2M	https://lup.lub.lu.se/student-papers/record/8904065
Susan Michaelis	Cranfield University	Implementation of the Requirements for the Provision of Clean Air in Crew and Passenger Compartments Using the Aircraft Bleed Air System	Master Thesis	June 2016	131		4.1M	https://purl.org/cabinair/MICHAELIS-2016
Tonje Trulssen Hildre, June Krutå Jensen	Norwegian University of Science and Technology	Fume Events in Aircraft Cabins	Master Thesis	June 2015	168		2.1M	http://hdl.handle.net/11250/2353003
Paul W. Magoha	Kansas State University	Incident-Response Monitoring Technologies for Aircraft-Cabin Air Quality	PhD Thesis	13.08.2012	398	download	38.5M	http://hdl.handle.net/2097/14187
Susan Michaelis	University of New South Wales	Health and Flight Safety Implications from Exposure to Contaminated Air in Aircraft	PhD Thesis	September 2010	932	download	6.1M	https://doi.org/10.26190/unsworks/23524
Chris Winder	University of New South Wales	Aerotoxic Syndrome	Master Thesis	August 2010	276		17.9M	https://perma.cc/EGH8-ZEPA
Nickolas Vakas	University of Wollongong	Interests and the Shaping of an Occupational Health and Safety Controversy: The BAe 146 Case	PhD Thesis	April 2007	297		1.4M	https://hdl.handle.net/10779/uow.27836445.v1

Thanks to the students for their enthusiasm to advance the topic! Copyright of student contributions is with the respective author. Most of the above theses are stored on the server of Hamburg University of Applied Sciences. Thanks for giving me permission to upload the documents. The documents of Hildre & Jensen and Magoha link to their respective university repository.

Media Coverage (selected)

Susan Michaelis Sadly Passed Away on 9 July 2025

Sick Pilots: Justice Recognizes the Reality

2023-10-31: Fumes often contaminate the air in airplane cabins. A known phenomenon, but whose health impact is contested by airlines. Pilots dismissed for unfitness have managed to have the causal link between their illness and polluted air recognized. On 20 October 2023, the Bordeaux judicial court recognized the causal link between a pilot's illness and his professional exposure.

Full story in English (archived), Original article in French (archived), Original article in French behind paywall (archived),

ARD/SWR: Schadstoffe in der Kabinenluft

Umfrage unter Bordpersonal: Es gibt viele Betroffene
Flugzeugexperte, Scholz: "Das Belüftungssystem ist eine Fehlkonstruktion"
Luftfahrtexperte der Grünen: Es muss jetzt endlich gehandelt werden
Personalvertretung von Lufthansa fordert Schutzmasken für Crew-Mitglieder

ARD/SWR, 2020-01-28: Schadstoffe in der Kabinenluft (Teil 1: SWR-Bericht mit Video - mit Scholz)
Meine technischen Ergänzungen zum Report als Kommentar deutsch

My technical additions to the documentary as a comment englisch

ARD/SWR, 2020-01-28: Schadstoffe in der Kabinenluft (Teil 2: Text des Beitrags)
ARD/SWR (German Television), 2020-01-28: Polluted Cabin Air (YouTube-Video with English Subtitles) englisch

ARD/SWR, 2020-01-28: Schadstoffe in der Kabinenluft (Teil 3: Atemschutzmaske für die Kabinenbesatzung)
ARD/SWR, 2020-01-28: Schadstoffe in der Kabinenluft (Presseinformation, PDF)
ARD/SWR, Report aus Mainz, 2020-01-28: Giftige Kabinenluft im Flugzeug? (Video, Vorschau)
Lufthansa, PV Kabine, 2020-01-07: Smoke, Smell, Fume Events (Forderung: Atemschutzmasken für Kabinenpersonal - Hintergrüde, PDF)
Dräger-X-plore-3300 (Die von der PV Kabine vorgeschlagene Atemschutzmaske)
The Aviation Herald: Latest research: Bleed Air Ducts can not be cleaned, pollutants deeply penetrate human bodies (News about the ARD/SWR Docu)
Markus Steinhausen, 2020-01-28: Kontaminierte Kabinenluft durch Fehlkonstruktion der Flugzeugventilation. LinkedIn

Schwäbische: Piloten klagen über Gesundheitsprobleme

Schwäbische, 2018-10-22: Piloten klagen über Gesundheitsprobleme (PDF), (Interview u.a. mit Prof. Scholz) (User=cabinair=PW)
In Web.Archive.

Die ZEIT: Gift in der Kabine?

Die ZEIT, 2017-10-19: Gift in der Kabine? (PDF), (Interview u.a. mit Prof. Scholz) (User=cabinair=PW)
Siehe auch: ZEIT ONLINE, in Web.Archive.

Sunday Times: EasyJet is First Airline to Go for Total Cabin Air Filtration

Sunday Times, 2017-09-17: Article (PDF) (User=cabinair=PW), Video.

More:
ORF2, KONKRET, 2017-09-22, 18:30: Video (Interview e.g. with Prof. Scholz).
ORF2, ZIB2, 2017-09-22, 22:00: Video (Interview e.g. with Prof. Scholz), Transcript, in Web.Archive.

EasyJet to go for Cabin Air Filtration in the Recirculation Path

Pall had announced already on 2016-12-05 (Web.Archive) that EasyJet would retrofit their fleet of A320 family aircraft with the latest Pall Aerospace PUREair Advanced Cabin Air Filters [in the recirculation].

More News

2020-12-18: Pressegespräch: 10 Jahre German Wings "Cabin Air Contamination Event" am 2010-12-19 mit "Fast-Katastrophe"

Einladung: Whistleblower-Netzwerk: Online-Pressegespräch zum "Underreporting" von Fume Events, Text archiviert
Bericht: Online-Pressegespräch "Fume Event"
Vortrag: Contaminated Aircraft Cabin Air – An Aeronautical Engineering Perspective
Pressespiegel: General-Anzeiger, Bonn, Kölner Stadt-Anzeiger

2020-08-10: HANDELSBLATT: Gefährliche Kabinenluft: Nervengifte in 10.000 Metern Höhe

Die Luft in Zivilflugzeugen ist potenziell gesundheitsschädlich. Endlich soll eine EU-Norm kommen – es zeichnet sich ein schwacher Kompromiss ab.

deutsch Text im HANDELSBLATT, deutsch Text archiviert.

englisch Dangerous cabin air: Nerve poisons at 10,000 metres altitude (PDF)

2020-07-31: JetBlue Pilot Wins Major Worker Compensation for Toxic Fume Exposure

The airline got accused of being "more concerned about keeping planes in the air than worker safety." The toxic fumes incident, or more specifically, "acute chemical inhalation" and "acute toxic inhalation," took place aboard an Airbus A320 and led to Captain Myers'devastating health problems.

englisch Text at Transport Workers Union of America (TWU), text archived.

2020-05-27: Open Letter - German Government Financial Aid for Lufthansa Must Included Money for Better Cabin Air

Read: P-COC: Open Letter - Lufthansa Financial Aids and Fume Events (PDF).

2020-05-21: € 9 Billion Lufthansa Bailout by German Government - Contaminated Cabin Air Likely to Remain Unnoticed!

"The two seats on the Supervisory Board should now be filled with experts who are aiming for Lufthansa's economic recovery and not pursuing a political agenda." (Handelsblatt quoting a politician.)
If this is the deal - even with that much of government money - Lufthansa (and the rest of the aviation industry) will again not be forced to adhere to the law when it comes to aircraft cabin air.
Read: D. Scholz: Demands to be Placed on Lufthansa Related to Cabin Air as One of the Prerequisites for Bailout (PDF).

2020-01-28: ARD/SWR (German Television): Polluted Cabin Air

YouTube-Video with English Subtitles (inspired by Prof. Scholz, realized by Markus Steinhausen after month of dedicated hard work)

See more information related to this documentary below!

Reporting by Aviation Herald

Far too often there is a CACE (Cabin Air Contamination Event) somewhere in the world to allow me to offer here an exhaustive list of such events. I have added here just a few quite extreme events once I came accross them and found time to look into them a little. In most cases, I just refer to Aviation Herald. Only occasionally, I have added something on my own. Aviation Herald is a good source, but also at times struggles to report about all CACEs. As I said, CACEs are just far too often. We need to change that!

2019-10-19: Aviation Herald: Accident: British Airways A320 at Paphos on Oct 19th 2019, fumes in cockpit, both pilots partially incapacitated

2019-08-22: Aviation Herald: Accident: Hawaiian A21N near Honolulu on Aug 22nd 2019, fumes and smoke on board prompt evacuation
Prof. Scholz: An analysis of the sequence of events!

2019-08-05: Aviation Herald: Accident: British Airways A321 at Valencia on Aug 5th 2019, smoke on board

2019-03-29: Five UK Airlines Sued Over Toxic Cabin Air Including British Airways and EasyJet

EasyJet, British Airways, Thomas Cook Airlines, Jet2 and Virgin Atlantic have all been served lawsuits by the union Unite, with a total of 51 cases to be heard. Four of the lawsuits involve pilots while the rest are being brought by members of cabin crew. Court actions involve crews who claim to have suffered chronic illness as a result of being exposed to toxic fumes. It could take up to a year before they're heard in court.

englisch Text at The Independent, text archived.

More Reporting by Aviation Herald - Selection of Incidences Before 2019

2018-12-10: Aviation Herald: Incident: Indigo A320neo at Kolkata on Dec 10th 2018, smoke on board
Impressive Video. My Comment on Twitter and and My Contribution on Twitter to the Discussion. "The occurrence was rated a serious incident and is being investigated by the AIB". Telegraph 2018-12-13: Bearing-oil leak blamed for IndiGo cabin smoke.

2015-07-17: Aviation Herald: Accident: Spirit A319 at Boston on Jul 17th 2015, fumes on board, captain died 50 days later

Action

CO Detectors

Sensors have been demanded by pilots and cabin crew for years, but they are still not introduced on board. There may be good reasons for NOT introducing air quality sensors on passenger aircraft. However, every individual on an aircraft may decide to get informed and this can not be denied. Therefore, immediate action could be taken without waiting for the ultimate industry solution of the problem - which may never come. This is especially important in failure cases like fume events. Failures compromising cabin air quality may alert people on board, but it may need some kind of objective confirmation before action can be taken. Situations with cabin air quality problems could also pass unnoticed without sensing. If cabin air is contaminated, it will show a mixture of many substances. Carbon monoxide (CO) will most probably be one of these substances. Simple logic tells us that it is sufficient to trace one bad gas in an abnormal quantity to conclude that the cabin air is not ok. CO is taken from the cocktail to be measured, because inexpensive and small CO detectors are available on the market. Pilots (cabin crew, passengers) should read the carbon monoxide (CO) concentration from a personal CO detector as an objective indicator in addition to the observations from their senses (nose and eyes). It is known from CO measurements on the BAe 146 that the CO concentration will be low even in a fume event [1]. For this reason, the CO concentration should not be compared against the limit value of 50 ppm (CS 25.831), but rather against values obtained under normal conditions (e.g. 2 ppm; as a frequent flyer you will find out for yourself soon).

[1] Global Cabin Air Quality Executive: Carbon Monoxide Database Collated on 345 BAe 146 Flights in UK, 2003-2004, 2006 (no online access).

UPDATE: Readings from CO detectors are mostly very low and are not anymore considered the best marker substance for engine oil. CO develops only at very high oil temperatures that are not always present. Better suited as a marker are Ultra Fine Partices (UFP). Good instruments to measure UFP are quite expensive. Tests are underway to find also inexpensive instruments to measure UFP. Another good marker substance could be formaldehyde. Instruments for Indoor Air Quality (IAQ) that offer the best combination of chemical sensors for aircraft cabins are under investigation.

Breathing Masks

Each member of the cockpit crew is protected by one onboard oxygen mask. Oxygen comes from a bottle and is available for the rest of the flight. Cabin crew have (at best) a smoke hood for their protection. The chemical oxygen supply in the smoke hood is intended only for short duration. A private breathing mask can protect people in the cabin in the very rare event of air contamination. A breathing mask filters the air and will do so for the rest of the flight. Inexpensive are the army standard breathing masks. Buy only new masks. Germany: "Bundeswehr Schutzmaske M65" (by Dräger). Better suited is a civil mask like the "Dräger X-plore 6300 Full Mask". It has a standardized 40 mm threaded filter connection. A suitable filter would be the "Dräger X-plore A2B2E2K2HGP3". This is a "combined filter" for "organic gases and vapours" (A), "inorganic gases and vapours" (B), and other substances.

Also this information is provided here; because I have been ask for it. Cabin crew members are increasingly concerned. Some already have a personal breathing mask in their carry-on baggage or intend to do so. By asking cabin crew members to consider to carry a breathing mask (in order to be prepared for a very unlikely event), I do NOT state that cabin air can be compared to the air after an attack with chemical weapons. What I argue is only this: A breathing mask (with a suitable filter) will protect people in "harsh environments". I do NOT consider the aircraft cabin such a "harsh environment". Therefore, a breathing mask will give sufficient protection in such cases where people have (claimed to) become ill in the aircraft cabin due to (potentially) contaminated cabin air. Employers have a legal duty to protect their employees. If employers do not act accordingly, cabin crew have the right to take measures themselves as deemed necessary.