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The health impacts of long haul flights

health impacts of long haul flights

One thing Australian expats are used to is flying long distances.  But do we all fully understand the health impacts of long haul flights?

Once only a pipe dream, air travel is now the quickest and most convenient for most people to travel long distances. With an estimated 8 million people in flight every day, air travel is becoming ever more accessible and affordable to much of the population, yet how is flying affecting our health?

Airlines are now capable of longer non-stop flights (such as the new Perth to London direct flights), and new records are being set year upon year. But with increasing flight times, passengers aren’t likely to see any major improvements in seating, leg room, air quality or any other facilities. Let’s take a look at the health impacts travelers may unwittingly be exposing themselves to on long-haul flights.


Plane cabins are seriously dry places. Air humidity levels are typically around 10%, much lower than most climates experience on the ground; in fact there is less air moisture in an aeroplane cabin than in the Sahara desert! Dehydration can lead to conditions such as headache, constipation, infection of the sinus or other mucous membranes, low blood pressure, dry eyes and more.

Physicians estimate that we lose between 1 to 2 litres of water on a 10 hour flight, and the limited quantities of water offered on the beverage carts are nowhere near enough to keep dehydration at bay. The Aerospace Medical Association recommends you consume about 200 ml of water for every hour spent on a plane. Tea, coffee and alcohol only make the problem worse, so try to stick to water, herbal teas or fruit juices only on long-haul flights. The U.S. Environmental Protection Agency once found that 15% of water on planes contains fecal matter, so rather than asking for extra cups of water, it’s worth bringing your own drink bottle and filling it up once through security at the airport, so that you have a ready supply of clean drinking water throughout the journey.

Deep Vein Thrombosis:

When we hear about the risks of DVT we often think of the older generations, with most younger people dismissing the affliction. In fact, DVT can strike travelers of any age and is increasingly claiming the lives of teenagers and twenty-somethings who spend long periods sitting in front of the computer gaming or engaging in other physically stationary activities. Deep Vein Thrombosis occurs when blood thickens and comes to pool in your lower extremities where it can congeal into clots. Dehydration can make this even more likely and it causes blood to thicken and become sticky, creating the perfect conditions for a clot to form. Often undetected until it’s too late, these clots can travel up to your lungs, causing a deadly pulmonary embolism, days or weeks after your flight.

Movement is the key to preventing DVTs.  When you move your legs, the muscle contractions push blood upwards and encourage circulation, so travelers on long haul flights should take any opportunity they can to move around. Get up every hour or so to walk to the toilet or take a stroll down the aisles. If this in impractical, try doing some ankle rolls or calf lifts while seated. For more information on DVTs and how to avoid them, check out our article How to Protect Yourself from Deep Vein Thrombosis on Long Plane Journeys.


The Journal of Environmental Health Research predicts that passengers are 100 times more likely to contract a sickness when travelling on a plane. The cramped, ‘sardines in a tin’ conditions of most plane cabins means that bacteria and viruses can spread like wildfire. A high concentration of people in a confined space makes it more likely for you to encounter contagious illness, and the likelihood of contracting something increases according to the amount of time you are exposed. Airborne particles can travel throughout the cabin, landing on people and surfaces such as dining trays and dry mucous membranes from dehydration make your body less able to fight off infection, making it probable that you will become infected.  Regular hand washing and use of antibacterial soap can go some way toward immunizing yourself against sickness.

health impacts of long haul flights

Low or poor quality oxygen:

The pressurized atmosphere in a plane cabin may result in reduced airflow, meaning that passengers can become oxygen deprived. Typically, a cabin contains only about 75% of the normal oxygen volume found in air, and reduced levels in the blood can cause dizziness, fatigue and headaches.

Air inside a plane is continually recycled through filters, however filtration costs both money and fuel, and these filters are not always cleaned or maintained as often as is ideal. Poor air filtration not only recirculates germs throughout the plane, but means that you are repeatedly breathing in air which is declining in quality throughout the flight, a situation which is worsened when a plane is delayed on the tarmac, as circulation reduced even further when the engine are not running.

Some airlines spray antibacterial or antiviral chemicals throughout the cabin, and while this may reduce your chances of catching an infection, these chemicals degrade the air quality in a different way and may be problematic for asthma sufferers.

Radiation and cancer:

Every time we fly, we are exposed to elevated levels of cosmic radiation. This radiation enters Earth’s atmosphere from space, so the higher your altitude and the thinner the atmosphere, the more you get. While generally considered to be at safe levels, the dosage is large enough that pilots are crew members are classified as radiation workers and are thought to be exposed to more radiation in a year than nuclear workers. A few hours in the air exposes you to about the equivalent radiation as you would get by having an x-ray taken; fine if you only fly occasionally, but may be cause for concern for frequent flyers. Nobody really knows how this radiation affects the human body, but cabin crew members have been found to be more susceptible to cancers than the general population, including breast cancer and melanoma. Whether this is due to radiation or other factors like repeated body clock disruptions is unknown. Iodine supplements are one of the most common anti-radiation measures available to civilians.


The most well recognized of any travel related ailments, jetlag isn’t necessarily just a short term inconvenience. It takes around 48 hours for your body clock to reset itself after a long flight, but accumulated disruptions to your circadian rhythms or ‘body clock,’ can have more serious effects on the body, and may cause nausea, fatigue, irritability, digestive issues and so on. A 2007 study also found that regular body clock disruptions could lead to cognitive decline, psychosis, mood problems, heart disease and cancer.

Hearing damage:

Takeoff measures in at around 110 decibels of sound and plane engines typically operate at 100 decibels throughout a flight. The human ear is able to withstand sound up to about 85 decibels without incurring damage, but exposure to noise above that level can damage the delicate hairs inside your cochlear, leading to hearing damage down the road. The ear can only take 15 minutes of exposure to sound levels of 100 decibels before damage occurs, a far shorter length of time than most flights! Excessively loud earphones are a huge cause of hearing loss, especially in younger people, which can pose an issue with the use of in-flight entertainment. Frequent fliers may benefit from wearing earplugs to block out excess noise during long flights, and always keep your headphone volume low enough that you can still hear your surroundings.

Digestive issues:

Bloating, bad breath and constipation are some of the common digestive problems on long haul flights. Sitting in a stationary position causes metabolism to slow down and the pressurized atmosphere in the cabin causes gases to expand inside your digestive tract, which can cause discomfort. Dehydration and unsuitable foods can make these problems worse. Check out our article about the best foods to eat when travelling on a plane for more information on how to avoid digestive problems in the air.

At first glance, the invention of the aeroplane has been a boon to tourists and expats alike. Gone are the days when the travel part of a trip could take days or weeks itself; now we are able to arrive at our destination quicker than previous generations could have imagined, but this comes at a cost. The human body wasn’t built to hurtle though the atmosphere in a ‘tin can,’ and the health implications shouldn’t be dismissed.

There’s no need to cancel your next holiday yet, though. Just planning ahead taking a few extra precautions to protect yourself can ensure that you arrive at your destination as healthy as ever.


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Australian Expat Investor Contributor

These articles have been written by an Australian Expat Investor Contributor. Please see their details in the relevant post. The views expressed in the article are his or her own and may not reflect the views of The Australian Expat Investor. If you are interested in contributing an article or story to The Australian Expat Investor please visit our contact page.

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