In-Flight Carbon Dioxide CO2 & Oxygen Levels on Commercial Aircraft
AIR QUALITY on COMMERCIAL AIRCRAFT - CONTENTS: an informal study of carbon dioxide level variation during in-flight conditions on long commercial aircraft found little variation by altitude nor flight duration. Some consumers speculated to the author that poor air quality, reduced oxygen, or elevated CO2 might explain dizziness or respiratory distress experienced by some airline passengers.
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Commercial aircraft air quality:
Airplane cabin IAQ, fresh air ventilation, and oxygen and carbon dioxide levels were examined by measuring CO2 and O2 levels during long flights.
This article reports the results of a limited study of the variation in oxygen levels and carbon dioxide levels during long commercial air flights in 2014. This study was made by performed by using safe, simple and accurate gas detection tube analysis to measure both oxygen and carbon dioxide levels at various points in fight.
Results suggest that the levels of these two gases in the aircraft cabin indeed varied, but not by much during long commercial airline flights at typical high altitudes.
Waters et al (2002) reported "Carbon dioxide exposures were highest on shorter and high-occupancy flights, aircraft
with greater recirculated-to-fresh-air ratio, and narrow
-bodied aircraft. In general
contaminant levels were low compared to standards. Carbon dioxide levels indicated lower
ventilation rates per occupant than
most other indoor environments."
[Click to enlarge any image]
Those authors measured aircraft cabin CO2 at
515 - 4902 ppm and reported that CO2 levels were likely to be elevated in aircraft cabins on short flights in full or nearly-full aircraft.
They also provide a succinct description of how cabin air is supplied to airline passengers:
Engine compressor bleed air is pre-conditioned, sent to the air conditioning packs, and
delivered to the cabin through a manifold that
permits mixing with recirculated cabin air.
Outside air is not filtered but the recirculation system incorporates air filtration; types and
efficiency of filters vary by aircraft.
Recirculation maintains air supply rate and minimizes
use of more costly bleed air. - Waters et al (2002)
I previously studied the rate of change of indoor CO2 in a crowded synagogue that had no functional fresh air ventilation system. During the religious service the CO2 level indoors increased significantly, possibly shifting an explanation of the apparent drowsiness of the congregants from Rabbi Arnold's sermon to the building's indoor air quality. One might ask if similarly the CO2 might increase in the cabin of a crowded airplane during a long flight - a different hypothesis than that offered by Waters et als and one that investigates the current (2014) ventilation rate on commercial aircraft.
I have received anecdotal reports of a air passengers experiencing dizziness and fainting during long air flights (Lukacher 2014) , typically transcontinental travel.
While altitude has been discussed regarding air passenger comfort anecdotal reports speculated on changes in either oxygen level or carbon dioxide level as possible contributors to the experiences of these passengers.
While altitude or other explanations for fainting and dizziness during long air flights may pertain, I wanted to investigate the cabin air quality, specifically oxygen and carbon dioxide, and to compare those results with air passenger speculations about oxygen and CO2 levels in aircraft during long flights.
Previously I have collected airborne particle samples using an adhesive air sampling cassette in order to examine in-cabin airborne particulates in the air stream from the cabin's ovehead air supply. Particulate levels down to 1u were very low: I did not find much of interest. Particulate filtration on modem aircraft appears to be quite effective at least for larger particles such as common dust, pollen, and mold spores. Very small particles such as bacteria and viruses were not studied by the author but were studied by some of the authors cited below.
In 2014, on a series of long commecial air flights including trips between Mexico and the U.S. and between the U.S. and New Zealand, the author used a simple air sampling pump made by Drager to collect periodic samples of the level of both carbon dioxide and oxygen in the passenger cabin of the commercial aircraft during those flights.
At left are the oxygen sampling tube (above) showing about 11.25% concentration of oxygen in the aircraft's cabin, and a carbon dioxide gas sampling tube after 20 pump strokes showing nearly 1500 ppm - a number that must be divided by two to obtain the actual concentration of about 750 ppm of CO2 for this measurement.
The data recorded included the total flight time, altitude, aircraft model and number of passengers aboard, along with the point in the flight by time and distance at which various samples were collected. The results are reported in the airplane cabin IAQ table below.
Table of Carbon Dioxide CO2 and Oxygen Levels Measured in Commercial Aircraft Cabins During Flight
Flight / Row / Date
Aircraft / Capacity
gers + crew
UA 1063 /
B737-800/900 / 145
EWR->MEX, est. Cabin Temp 70F,Tube 100/a, 10 pump strokes
Control. Cabin air samples collected @ lap height
20 pump strokes for precision
UA 718 / r8 /
2 h 40m
A320 / 120-150
MEX->SFO Control, prior to takeoff
NZ 7 / r14 /
B747 400 / 416-524
SFO->AKL dep , climbing, 20 min. into flight. Total distance 10,618 Km
8 hrs from destination, outside temp -42C
over PagoPago, outside temp -46C
NZ 531 /r10/
NZ 548 / r13/
NZ 2 / r45/
250 + crew
Traveled: 5054 Km
Total distance 10,373 Km
Over the Equator Lat 0.09S
Speed 946 KmH
35,000 ft 10,668m
UA 274 /r22/
1. Time in minutes into the total flight time
2. Dates are given in international format dd/mm/yy
3. Second reading using same sampling tube by doubling number of pump strokes for increased precision.
4.Drager gas detection tubes used: colorimetric type. Selecting the proper detection device sensitivity range is important for obtaining accurate measurement of gases in air. I used:
Carbon Dioxide level measurement: Drager Rohrchen Carbon Dioxide 100/1, certified manufacturer ISO 9001. This tube is designed for measuring CO2 levels are between 100 - 3000 ppm. Ten Drager gas pump measurement strokes are used with this tube, or the operator can use 20 pump strokes and divide the resultant measurement by 2 for increased precision. Standard deviation is +/- 10-15%. The tube colour changes from white to violet on exposure to CO2. and operates at temperature ranges from 15°C to 25°C and at humidity less than or equal to 23 mg/L (corresponding to 100% RH at 25C). An atmospheric correction factor to be applied is F=1013 / actual ATM pressure.
Oxygen level measurement: Drager Rohrchen Oxygen 5%, certified manufacturer ISO 9001. This tube is designed for measuring the level of oxygen in air in the range of 5% to 23% by volume. One pump stroke is used to perform a measurement.
Standard deviation is +/- 10-15%. The tube changes color from blue-black to white on exposure to oxygen and operates in the temperature range of 5°C to 50°C and at humidity from 0-40 mg/L. The literature includes a correction factor F = 1013hPa (14.692 psi) / actual atmospheric pressure - a factor that may be especially pertinent at high altitudes or in examining aircraft cabin conditions. The detector tube also has two reading scales, chosen based on which Drager sampling pump is used. Because this tube heats to as much as 100°C it should not be used where explosive gases may be present.
The Dräger sampling pump was leak-tested prior to use of the detection tubes by using the manufacturer's recommendations. The pump was air-flushed between measurements.
Draeger Safety Inc.
101 Technology Drive
USA, Tel: +1-800-858-1737
+1-412-787-2207, Website: http://www.draeger.com (their website was not functioning properly - Nov. 2014)
Draeger Safety Inc. (Gas Detection Systems)
505 Julie Rivers Suite 150
+1-800-375-3073. Drägerwerk AG & Co. KGaA
5. Other gas concentration in air conversions:
1 ppm CO2 = 1.8 mg CO2M3
1 mg CO2 = 0.56 ppm CO2 (at 20°C, 1013hPa)
With additional measurement reports pending, I found in-flight cabin air quality measurements of oxygen to be relatively stable, ranging from 11.2% to 12.5%.
Typical outdoor CO2 levels are between 350-400 ppm (0.035% - 0.04%) or up to 500 ppm by some sources.
Carbon dioxide levels measured in-flight in the aircraft cabin ranged between 0.04% or 400 ppm and 0.1% or 1000 ppm to date in our studies and were measured at close to 0.5% or 5,000 ppm in earlier studies.
As indicated at CO2 HEALTH EFFECTS, occupants are unlikely to be affected or to notice CO2 levels under 2% or 20,000 ppm - a far higher number than in-flight aircraft cabin carbon dioxide levels.
Opinion: Perhaps to investigate or reduce air traveler complaints of dizziness or fainting we should look more closely at altitude and cabin pressures as well as other factors such as passenger hydration (drink plenty of fluids), anxiety, physical stresses before the flight (rushing, carrying bags), passenger movement & stretching during flight (avoid blood clots), the increasingly cramped seat space limitations and cramping, and aircraft cabin ozone levels.
Note: my measurements of equivalent altitude indicate that typical cabin pressures during flight give an altitude of about 7,000 feet. As I have observed simply among visitors to San Miguel de Allende, Mexico, (altitude about 6500 feet), unaccustomed people are often physically stressed at that altitude, experiencing shortness of breath and on occasion dizziness.
Opinion: An increase in respiration rate by an "out-of-breath" passenger experiencing quite understandable anxiety can exacerbate those conditions.
Bagshaw et als (2002) point out that
Commercial air carriers train their flight attendants to recognize common
of distress and to respond to medical emergencies with first
techniques, and the use of emergency medical oxygen. ... It cannot be
overemphasized that these medical kits are only for emergency use and not for
routine medical care.
In general, ... studies have consistently revealed levels of organic
substances, carbon monoxide, carbon dioxide, and airborne particles in the cabin
air well below regulatory standards and below those encountered in offices, the
street, or subway.
One exception is ozone, a substance found naturally in the atmosphere at
altitudes where most commercial aircraft fly. It enters the cabin with outside air
that is used for cabin ventilation. Ozone is a respiratory system irritant and can
cause chest tightness, coughing, and shortness of breath if exposure occurs at
high enough concentrations. In general, low levels have been found in aircraft
cabins although, in several instances, levels were measured slightly exceeding
regulatory standards. Most aircraft flying at altitudes and latitudes where high
ozone concentrations are encountered now have ozone converters which break
down the ozone before it reaches the cabin. - Bagshaw (2002)
Keep calm. Carry on.
Research on In-Flight Air Quality, Oxygen & Carbon Dioxide Levels & Other Factors
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[Do air travel passengers consider aircraft cabin air quality when choosing an airline?]
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Waters, M. A., T. F. Bloom, B. Grajewski, and J. Deddens. "Measurements of indoor air quality on commercial transport aircraft" [PDF] In Indoor air 2002: proceedings of the 9th international conference on indoor air quality and climate, Santa Cruz, California, pp. 782-787. 2002. Abstract: Exposures to cabin environmental contaminants were measured on 36 commercial transport
aircraft. The objectives were to characteri
ze levels of contaminants and evaluate the
relationship between flig
ht factors such as aircraft size
, occupancy, ventilation, and flight
length, and environmental parameters. Monito
ring was conducted at two coach locations for
the duration of the flight for
VOCs, nitrogen oxides, CO, CO2
, temperature, relative
humidity, total particulates, and barometric pressure.
Five-minute average concentration
ranges were: CO
515-4902 ppm; O
<0.05-0.24 ppm; CO <0.2-
2.9 ppm; nitrogen oxides
<0.05-2.0 ppm; and total pa
rticulates <0.028-0.197 mg/m
. Gate-to-gate average
concentrations of VOCs we
re: toluene <3-130 ppb, limonene
<3-12 ppb, and ethanol <0.8-2.4
Carbon dioxide exposures were highest on shorter and high-occupancy flights, aircraft
with greater recirculated-to-fresh-air ratio, and narrow-bodied aircraft. In general
contaminant levels were low compared to standards. Carbon dioxide levels indicated lower
ventilation rates per occupant than
most other indoor environments.
Zhang, Yuanhui, Yigang Sun, Aijun Wang, Jennifer L. Topmiller, James S. Bennett, and RW BESANT. "Experimental characterization of airflows in aircraft cabins, Part II: Results and research recommendations. Discussion." ASHRAE transactions (2005): 53-59.
Zitter, Jessica Nutik, Peter D. Mazonson, Dave P. Miller, Stephen B. Hulley, and John R. Balmes. "Aircraft cabin air recirculation and symptoms of the common cold." Jama 288, no. 4 (2002): 483-486.
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A Toxic Gas Testing Plan: A Gas Sampling Plan for Residential and Commercial buildings lists some of the toxic indoor gases for which we test, depending on the building complaint and building conditions
Gas Exposure Hazard Levels: for Toxic Gas Exposure to Ammonia, Arsine, Arsenic, Bromine, Carbon Dioxide, Carbon Monoxide, Hydride, Ozone - allowable exposure levels and hazard levels
Formaldehyde: US EPA. UFFI (Urea Formaldehyde Foam Insulation) was previously considered a hazard (formaldehyde outgassing).
Subsequent research virtually closed concern regarding this material; however formaldehyde appears to remain a health concern for sensitive individuals.
Ozone Warnings - Use of Ozone as a "mold" remedy is ineffective and may be dangerous.
Sampling for gases in air such as VOC's, MVOC's, toxic chemicals, and combustion products.
Unfortunately no single test or tool can detect all possible building contaminants. We use methods and equipment which can test for common
contaminants. If the identity of a specific contaminant is known in advance we can also test for a very large number of specific contaminant
gases in buildings.
We use gas sampling equipment provided by the two most reliable companies
in the world, Draeger-Safety's detector-tubes and Drager accuro� bellows pump, the Gastec� cylinder pump
and detector-tube system produced by Gastec or Sensidyne, and
we also use Sensidyne's Gilian air pump. For broad screening for combustibles and a number of other
toxic gases and for leak tracing we also use Amprobe's Tif8850. All of these instruments, their applications, and sensitivities (minimum detectable limits) for specific
gases are described in our Gas Sampling Plan online document.
 Per Levéen, email comments 23 May 2009
. Mr. Levéen is with Telia, the leading mobile telephone operator in Sverige (Sweden). By telephone Telia (not Mr. Levéen) can be reached at
90 200 or From abroad at +46-771-99 02 00
Lukacher, Joanne, personal communication to author, June 2014, Poughkeepsie, NY.
Dr. Roy Jensen, Department of Chemistry, Grant MacEwan College, Edmonton, AB for technical review and critique 8/23/07.
Dr. Jensen notes that if we increase the CO2 level in air in an enclosed space from
its normal level of about 0.03% (we counted it as starting at 0) to a level of 1.4%, we obtain a corresponding
decrease in the oxygen level from its normal level (at sea level) of about 20.9% down to 19.5%, for a 6.7%
reduction in the amount of oxygen available. The amount of oxygen lost is 6.7 % (1.4/20.9 * 100 %). Our earlier version of this document was incorrect in
 Stephen Fisher,
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E-mail: email@example.com [by email, Feb 2012] Quoting from the company's website
KD Fisher & Co. Pty. Ltd., Safety and Welfare: OHS & W training facilities located on premises; Gas detection monitoring & consultation; Safety & Security products; Electric components, Power & switchgear products, Electrical/Electronic service & engineering
Mr. Fisher adds "Our company is family owned, and employs 30 personnel, and has been specifying, and designing gas detection systems, using "bought in" detectors from overseas manufacturers, and developing sampling systems to allow the most proficient system for many applications, including jet fuel leakage detection systems for military aircraft hangars, and tanker parking shelters, for the Australian Dept. of Defence. "
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This document consists of selected reproductions from the CCOHS (Canada's National Occupational Health & Safety Resource) with minor Australian applications & modifications, and cites the InspectAPedia carbon dioxide gas hazards article found above on this page.
 GAS EXPOSURE EFFECTS, TOXIC Toxic Gas Exposure Hazards and Test Protocols including links
to our toxic gas exposure screening and gas testing protocols.
 "Table Z-1 Limits for Air Contaminants, 1910.1000 Table Z-1" OSHA standard for air contaminant limits (http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=9992) - includes for CO2, Carbon dioxide.........| CAS No. 124-38-9 | 5000 ppm | 9000 mg/m3 limits for carbon dioxide as an air contaminant.
 Klemens C. Baczewski PE, email correspondence, 4/29/2009 discussed correct CO2 calculations.
 Taylor, Lewis G. and G. Oscar Kreutziger, The Gaseous Environment of the Chick Embryo in Relation to Its Development and Hatchability, 1968 (printout does not include the Journal)
 Holloway and Heath, 1984 Ventilatory Changes in the Golden Hamster..., Laboratory Rat...., Comp. Biochem. Physiol., Vol. 77A, No 2, pp. 267-273
 Bruggeman et al. 2007 Acid-base balance in chicken embryois...incubated under high CO2 concentrations... Respiratory Physiology and Neurobiology 159:147-154
 De Smit et al, 2006 Emryonic developmental plasticity of the chick: Increased CO2 ... Comparative Biochemistry and Physiology, Part A 145: 166-175
 Bar-Ilan, Amir and Jacob Marder, Adaptations to Hypercapnic conditions in the Nutria..., Comp. Biochem. Physiol. Vol 75A, No 4, pp 603-608, 1983
 "Health Effects of Carbon Dioxide Gas", CCOHS, Canadian Centre for Occupational Health and Safety, web search 02/15/2012, original source: http://www.ccohs.ca/oshanswers/chemicals/chem_profiles/carbon_dioxide/health_cd.html
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