Visit our Re-post guidelines
Did you know that the air you breathe on a commercial airliner comes directly from the engine, complete with engine oil, lubricants and hydraulic fluid? A study confirms the link between contaminated cabin air and aerotoxic syndrome. Learn what you can do to protect yourself and your family
If you don't feel well after air travel, it might be more than simple jet lag. From the parking garage to the baggage carousel, your body undergoes a fusillade of toxic assaults. You may eat toxic food, drink toxic water, and touch contaminated surfaces--and then your body is bombarded by body scanners, Wi-Fi and cosmic radiation.
On top of all that, the air in the airplane is toxic.
For six decades, the airline industry has turned a blind eye to the adverse health effects of contaminated cabin air. Since warm air is needed for both engine propulsion and human respiration, aircraft manufacturers decided decades ago to combine the two by bringing air through the engine to heat it, then bleeding it directly into the cabin--unfiltered. This air brings with it a toxic mix of engine oil, lubricants, and various hydrocarbons. As noted by US Attorney Alisa Brodkowitz, the only air filters are the lungs of passengers and crew.
Modern aircraft have no chemical sensors--save for the noses of the humans onboard. Background levels of contamination are sometimes but not always detectable by smell, and not all incidents are recorded in flight logs or reported to aviation authorities.
Engine oils leak into the air supply, by design. Their chemical signature is regularly found in aircraft cabins and cockpits. Repeated exposures have created a new occupational disease called "Aerotoxic Syndrome" suffered by pilots, flight attendants and other crew--and unfortunately, some passengers as well. Extensive evidence confirms that frequent exposures are occurring, and health and flight safety are being compromised.
The role bleed air plays in the reported illnesses has been the subject of much debate, but a study recently published by the World Health Organization (WHO) provides solid evidence that contaminated cabin air is making people sick. The study took an in-depth look at the effects of "contaminated air events" (aka fume events) on the health of aircrew to determine whether reported symptoms are consistent with exposure to pyrolysed (decomposed due to heating) jet engine oil and other fluids, or if the symptoms could be attributed to other factors. Researchers concluded the following:[i]
A clear cause and effect relationship has been identified linking the symptoms, diagnoses and findings to the occupational environment. Recognition of this new occupational disorder and a clear medical investigation protocol are urgently needed.
A Flying "Gas Chamber"
Exposure to extreme temperatures produces a wide range of toxic compounds. Jet exhaust, and therefore cabin air, are tainted with petrochemicals, carbon monoxide, ozone, benzene, toluene, formaldehyde, acetaldehyde, deicing agents, hydraulic fluid--and even fecal matter and pesticides.[ii] [iii] [iv] In terms of Aerotoxic Syndrome, the most significant players appear to be the organophosphates, which will be my focus in this article.
All aircraft engines leak oil. Jet engines require synthetic oils for lubrication, and these oils contain chemicals such as tricresyl phosphate (TCP), which contains several compounds, one of which is tri-ortho-cresyl phosphate (TOCP). TCP is an organophosphate with known neurotoxic effects in the same category as sarin gas. TCP and other noxious agents are sometimes odorless--so you may not know you're inhaling them, which makes them all the more dangerous.[v] According to the WHO study:
Transient, low-level oil leakage over the engine oil seals into the aircraft air supply occurs during normal flight operations, with less frequent, higher level leakage under certain operational conditions (e.g. seal wear or seal failure). The use of pressurized air from the engine compressor to both seal the oil-bearing chamber and supply cabin bleed air provides a mechanism for low-level oil leakage in routine engine operations.
While many experts have suggested that oil leakage is associated only with rare failure events, others now recognize that chronic exposure is caused by the so-called tiny amounts of oil vapors released by oil leaking continuously over the seals during engine power changes.
Most medical practitioners are unaware of Aerotoxic Syndrome. Sufferers are misdiagnosed with a variety of other illnesses that miss the root of the problem and result in inappropriate treatments. The prime suspect for Aerotoxic Syndrome is TCP, which is found in 25 to 100 percent of in-flight air samples.[vi] TBP (tributyl phosphates) are found in 73 percent of flights, and triphenyl phosphate metabolites have been found in 100 percent of urine samples.
It is believed the primary effects of TCP come from its disruptions of acetylcholine metabolism. Acetylcholine is a natural neurotransmitter found in your central and peripheral nervous system. Neurotransmitters normally have a short half-life because they are rapidly degraded by enzymes, preventing their build-up. When organophosphates in bleed air impede the enzyme acetylcholinesterase, the resulting increase in acetylcholine overstimulates acetylcholine receptors, giving rise to central and peripheral nervous system symptoms.
High TCP exposure is known to cause neuropathy, paralysis, and damage to myelin sheaths, similar to what happens with multiple sclerosis. Symptoms can present immediately or be delayed by a couple of weeks, with varying severity. Symptoms can be triggered by higher-dose episodes (fume events), as well as low level exposures associated with routine air travel. Even the smallest dose can produce symptoms in susceptible individuals, depending on factors such as previous exposure history, genetics, age, overall health and ability to detox. Chronic effects are common.
The relationship between toxic inhalants and reported symptoms has been difficult to establish for a number of reasons. Another problem is that toxicants cause a wide range of symptoms that are not always easy to connect to exposure, made even more challenging if the effects are delayed.
Aerotoxic Syndrome symptoms can mimic other conditions such as multiple chemical sensitivity (MCS), mold toxicity, chronic infections, drug reactions, "sick building syndrome," chronic fatigue syndrome (CFS), and neurodegenerative diseases such as Parkinson's and multiple sclerosis (MS)--making identification a challenge. Many aerotoxicity victims describe feeling like "zombies" or perpetually intoxicated.
Medical investigation of Aerotoxic Syndrome should focus on organophosphate poisoning, as many of its symptoms are typical of poison-induced neurological injuries. Aerotoxic Team provides a list of jet fluid compounds that have been detected in crews' body fluids, and these specific compounds should be included in any lab analysis for toxic exposures, along with the more common toxins (pesticides, heavy metals, etc.). There is also a specialized hair analysis kit that checks for organ contamination from jet-oil TCP and five compounds, also available through the Aerotoxic Team website.[vii] The test must be performed within three to four months of exposure.
The ten most common acute and chronic health effects noted in the WHO study are listed below.
- Breathing problems
- Impaired cognition, memory and performance
- Vision problems
- Nerve problems
- Cold/flu like feelings
An Epidemic of Underreporting
All current transport aircraft use the bleed air system to provide cabin ventilation, except for the newest airliner, the Boeing 787. Boeing's "Dreamliner" incorporates bleedless technology using fresh air drawn in through inlets at the wing roots. You might think this would be a great selling point for Boeing's new jet--but they do not feature the airliner's "clean air design" in its marketing copy. Why?
Bringing attention to this feature would shine the spotlight squarely on the widespread air quality problems characterizing all of its OTHER aircraft. There are about 19,000 airliners currently in operation, and just over 280 are 787's. Based on that statistic, we can conclude that only about 1.5 percent of transport aircraft are safe to fly.
The fact that Boeing redesigned the 787's ventilation represents a tacit acknowledgment of the industry-wide problem of contaminated air and is one step toward a permanent solution. However, the vast majority of aircraft are still in the technological dark ages, with public awareness of health risks only starting to emerge.
Jet engine chemicals are routinely found in the blood of pilots.[viii] As I'm sure you would agree, compromising the neurological fitness of pilots should be taken as seriously as a mechanical defect in the plane--after all, pilots are essential to keeping our planes safely in the air. It is inexcusable for the industry to continue ignoring this problem.
It will be consumers and non-governmental advocacy organizations, such as those listed at the end of this article, that will force the industry and its regulators to make this issue a priority. If just one airline in this country took measures toward addressing the problem, it would see huge support by an increasingly educated consumer base--and that's you and those with whom you share this article! Short of redesigning existing aircraft, the Aerotoxic Association proposes the following solutions:[ix]
- As bleed air is not presently filtered, installation of bleed air filtration systems would eliminate the problem, although a technically efficient system has not yet been developed.
- The French oil company NYCO has developed a less toxic formulation, which has recently been introduced to the EasyJet aircraft fleet--a step in the right direction.
- Chemical sensors to detect contaminated air in the bleed air supply would alert pilots to a problem allowing for prompt intervention, as confirmed by a 2017 study.[x]
Until the airlines implement some greatly-overdue changes, there are a few things you can do to protect yourself from exposure to toxic inhalants when you fly. At the top of the list is wearing an appropriate mask.
Travel Masks Can Be a Lifesaver for Your Family
There are many kinds of masks on the market that can protect you from air pollution. The Aerotoxic Association has a page about masks specifically geared for airline travel, with the following guidelines:[xi]
If you are looking for a small, foldable mask with good protection you should always check out the technology they use. It should also indicate for which particulates, VOC's, type of fumes, smoke, gas etc. the specific mask is good for, and that it has an "activated carbon" filter within.
They recommend Cambridge Mask Co., which offers masks with the correct filtration technology in five different sizes, from infants on up. Cambridge masks are soft and foldable and meet the NIOSH N99 standard for filtration, which means filtration of 99 percent of particulates, 99.6 percent of viruses and 99.8 percent of airborne bacteria--so you will also receive some protection from those uninvited pathogens that can hitch a ride home in your respiratory tract.
Cambridge Mask Co. is affiliated with the Aerotoxic Team, so when you purchase from them you are also supporting the important work this organization is doing for the cause. To order, please visit the mask page on the Aerotoxic Team website--and make sure to add the code AEROMASK at checkout to receive a 10 percent discount.[xii] Many people report that these masks run small, so keep that in mind when you order.
It's worth noting that aircraft drop-down oxygen masks are used only for cabin decompression--pilots do not drop them in the event of smoke or fumes in the cabin. These deliver 50 percent oxygen and 50 percent cabin air so they are of little use during a fume event.
Other Ways to Protect Yourself and Your Loved Ones When Flying
In addition to wearing a mask, keep in mind the following:
- Stay well hydrated before and during a flight by drinking plenty of pure water (filtered water from home or bottled water, not airline water).
- Avoid departing in an exhausted or stressed state as that may compromise your immune system.
- Adjust overhead air vents so the flow is directed away from you; if you suspect a fume event, turn the vent off immediately.
- Many people coughing on a flight may indicate an air contamination problem.
- Report unusual smells or visible smoke to the flight crew and ask them to alert the captain. The smell of these fumes has been described as wet dog-like, dirty socks, burning oil or electrical. You can file a fume event report online or using this QR code, if you have a smart phone.
For more information about this issue, the following resources and organizations may be helpful.
- Global Aerotoxic Team[xiii]
- Information for passengers[xiv]
- Toxic Free Airlines: protocols, fume reporting guidelines and forms, informational handouts and more[xv]
- Facebook pages: Flightoxic International,[xvi] Global Aerotoxic Team,[xvii] Toxic Free Airlines,[xviii] Aerotoxic Association[xix]
- Exposure to Aircraft Bleed Air Contaminants Among Airline Workers: A Guide for Healthcare Providers[xx]
- Documentary by 60 Minutes Australia (free)[xxi]
- Documentary: "Angel Without Wings"[xxii]
- Documentary: "Unfiltered Breathed In: The Truth About Aerotoxic Syndrome"[xxiii]
Air travel has many associated risks, and contaminated air is probably the least well known. You can protect yourself by exercising a few basic precautions, such as wearing a mask. Raise awareness about this important issue! Share this article with your friends and family, and educate other passengers as the opportunities arise. Write to airline and aviation regulators insisting that toxic air detectors be fitted to all passenger jets, and encourage others to do the same.
I would like to express my gratitude to the Aerotoxic Team for their contributions to this article, and for spearheading the movement toward toxic-free air on all aircraft, on behalf of passengers and crew worldwide.
[i] S Michaelis, J. Burdon, and V. Howard, "Aerotoxic Syndrome: A New Occupational Disease?" Public Health Panorama June 2017; 3(2): 141-356, https://www.euro.who.int/__data/assets/pdf_file/0019/341533/5_OriginalResearch_AerotoxicSyndrom_ENG.pdf, accessed July 14, 2017.
[ii] C Winder and JC Balouet, "Aerotoxic Syndrome: Adverse Health Effects Following Exposure to Jet Oil Mist During Commercial Flights," Aerotoxic Association, June 10, 2014, https://aerotoxic.org/information/reports-and-evidence/aerotoxic-sydrome-adverse-health-effects-following-exposure-jet-oil-mist-commercial-flights/, accessed July 14, 2017.
[iii] SC Herndon et al., "Hydrocarbon emissions from in-use commercial aircraft during airport operations," Environmental Science and Technology 2006; 40(14):4406-4413, https://www.ce.cmu.edu/~gdrg/readings/2006/07/18/HerdonAirportEmissions.pdf, DOI: 10.1021/es051209l, accessed July 20, 2017.
[iv] "3. Health Effects of JP-5, JP-8, and Jet Fuels," Agency for Toxic Substances and Disease Registry (CDC), pages 23-143; https://www.atsdr.cdc.gov/toxprofiles/tp121-c3.pdf, accessed July 21, 2017.
[vi] S Michaelis, "Implementation of the Requirements for the Provision of Clean Air in Crew and Passenger Compartments Using the Aircraft Bleed Air System." Cranfield University Master's Thesis, June 2015, https://www.susanmichaelis.com/pdf/2016_Susan%20Michaelis_MSc%20Cranfield-Clean%20air%20requirements%20using%20bleed%20air%20system.pdf, accessed July 14, 2017.
[viii] "German scientists find dangerous gas in plane cabins," The Local, February 16, 2016, https://www.thelocal.de/20160216/german-scientists-find-dangerous-gas-in-plane-cabins, accessed July 14, 2017.
[x] BW Jones et al., "The nature of particulates in aircraft bleed air resulting from oil contamination," 2017 ASHRAE Winter Conference Papers, LV-17-C046, https://www.aerotoxicteam.com/uploads/6/0/3/8/6038702/jones_et_al_nature_of_particulates_in_oil_contaminated_bleed_2017.pdf, accessed July 21, 2017.
[xii] "Protection on Board from Contaminated Cabin Air," Global Aerotoxic Team, https://www.aerotoxicteam.com/protect-yourself-with-masks.html, accessed July 20, 2017.
[xviii] Toxic Free Airlines, https://www.facebook.com/ToxicFreeAirlines/?hc_ref=SEARCH.
[xx] R Harrison et al., "Exposure to Aircraft Bleed Air Contaminants Among Airline Workers," Toxic Free Airlines, https://www.toxicfreeairlines.com/images/stories/medicalprotocolforhcp2008.pdf, accessed July 14, 2017.
[xxiii] Vimeo, "Unfiltered Breathed In: The Truth About Aerotoxic Syndrome," November 22, 2016, https://vimeo.com/ondemand/unfilteredbreathedin?utm_source=email&utm_medium=vod-rentalexpire-201602&utm_campaign=29548, accessed July 14, 2017.