'Cabin Pressure to Dehydration': Can Long-Haul Flights Be Bad For Your Health?

Qantas Airways will start “non-stop flights from Australia’s east coast to London” by late 2025.

FIT breaks down what this might mean for flyers on these long-haul flights.

(Photo: Garima Sadhwani/FIT)

Australia’s flagship airline Qantas Airways recently announced that it will start 'non-stop flights from Australia’s east coast to London' by late 2025.

Why should this be of interest to you? Because Qantas is proposing flights that will be in the air for over 19 hours non-stop. Currently, the longest flight to operate from India is an Air India aircraft from Bangalore to San Francisco – that flies non-stop for over 17 hours.

Experts point that these long-haul flights may have some repercussions on our health. Why is it a concern? FIT breaks it down.

What Happens to Your Body On Long-Haul Flights?

Dr Tarun Sahani, Senior Consultant, Internal Medicine, Apollo Hospitals, Delhi, explains, "When you’re sitting for a prolonged period of time, the blood in your lower limbs can start clotting."

This could lead to Deep Vein Thrombosis or DVT. This happens due to poor blood flow when you haven’t moved in a long time. The clots usually form either in your lower legs or your thigh.

And while this can impact anyone who is in a cramped space and is immobile for long, it impacts obese people and new mothers the most. This immobility can be dangerous since muscle contraction is what primarily leads the blood from the legs to reach the heart.

But Dr Sahani adds:

"Most airlines instruct you on some exercises for the lower limbs to prevent this. Take a walk in the cabin every few hours. Move your toes back and forth. Turn your ankle around. There are exercises for your joints that you can do while sitting."

Dr Farah Ingale, Director, Internal Medicine, Fortis Hiranandani Hospital, Vashi, agrees with Dr Sahani. She explains that immobility can cause stiffness, swelling, pain, and cramps in the legs.

But again, what you can do to avoid this is get up and move every 3-4 hours or perform leg exercises even while you’re seated. Just anything that prevents your legs from getting cramped.

However, there are other health issues that might crop up in long flights as well. For instance, dehydration.

Why Dehydration Is a Concern?

The air on airplanes is super dry which means flyers can get dehydrated quickly. Not just that, most people either indulge in liquor, soft drinks, or caffeine on flights, which are diuretics and cause your body to get rid of sodium and water quicker. 

This dry air will also cause your skin and your mucus membranes to be dehydrated. 

The end result? Your body loses a lot of fluid.

A report in Quartz read:

"Cabin-air humidity is usually less than 20 percent (...) Once you get into long-haul territory, serious fluid loss begins to set in. In a 10-hour flight, the average woman might lose 1.6 liters of water (just under half a gallon), with men losing about 25% more."

In addition to that, Dr Ingale says that if you’re dehydrated, it also precipitates the blood clots, increasing the risk of DVT for the flyer. "Keep moving, drinking water, and use DVT stockings if need be," she recommends.

Other affects of dehydration include:

• Fatigue

• Attention deficiency

• Drying out mucus membranes

The dry air, low humidity, and the low cabin pressure aren't the best for your health.

But What Is Cabin Pressure? Why You Should Care?

A lot of people feel varying amounts of pain in their ears during take-off and landing. This is because during both of these instances, the pressure inside the aircraft is changing.

So if the pressure is changing only during take-off and landing, the duration of the flight shouldn't matter, right? Actually, no.

On long-haul flights, earaches and headaches might be a bigger issue. 

"Earaches can be a bigger concern in such long-haul flights because of the disturbed equilibrium in the barometric pressure. We recommend using earbuds for longer flights, especially for children and infants."

Dr Farah Ingale, Director, Internal Medicine, Fortis Hiranandani Hospital, Vashi

This is also because the amount of oxygen in the air will be lower than usual and breathing itself might be more difficult. You might just sleep and fart more on long-haul flights.

Dr Ingale says, "Lower oxygen levels in the cabin can lead to a lower supply of oxygen to your brain, called hypoxemia, which might affect your cognitive functions."

Are There Other Health Hazards Too?

While these might seem like insignificant things on shorter flights, during long-haul flights, you might have to pay extra care to them.

• Sanitising any surfaces you might touch

• Being mindful of your exposure to radiation if you have any comorbidities

• Avoiding caffeine, liquor, cold foods, etc since digestion is a little tricky due to cabin pressure

Dr Ingale explains, "Indigestion can occur on long flights, and one might get a heavy bloated stomach. Low cabin pressure might be the reason behind this. "

Okay, And What Can One Do About These Health Impacts?

People who might have any diseases, especially diabetics and people with cardiac issues, or even senior citizens should take their medicines on time and consult a doctor before taking such long flights, says Dr Sahani.

He adds, "If someone has a urinary or prostate problem, you need to plan your journey beforehand and prepare for it." This might include hydrating yourself, starting a day prior to the flight, eating before boarding, packing your own light meals for the journey, etc.

But there's no need to panic.

"Most of these things are preventable. But if you’re a senior citizen or have any comorbidities, you need to plan and anticipate any problems you might face, and prepare for them accordingly."

Dr Tarun Sahani, Senior Consultant, Internal Medicine, Apollo Hospitals, Delhi