14 Conditions that can be aggravated by long airplane flights

• Airplanes nowadays tend to have high efficiency particulate arresting (HEPA) air filters installed, similar to those used in hospital operating theaters. However, there are other factors at play which may affect those with underlying health conditions during flights.
• A study undertaken by the WHO found that occurrences of deep vein thrombosis were 2–3 times more likely following a flight of more than 4 hours in duration.
• Can pregnant women travel by air? In addition to patients with underlying health conditions, pregnant women, young infants, and those who have recently been diving, must all beware when traveling by air.

Air travel is now hugely popular, but the problem of passenger illness has also significantly increased, especially when flying long-haul and across continents. Most airplanes now have air circulation systems that can circulate up to 50% of the air in the passenger cabin, with that air being circulated approximately 20-30 times per hour. Additionally, the circulated air is filtered through high efficiency particulate air (HEPA) filters, similar to those used in hospital operating rooms, to trap dust particles, bacteria, fungi, and viruses. However, other factors may affect those with certain underlying health conditions when flying long-haul.

1. Heart Disease
   Patients with coronary artery disease or congestive heart failure should undergo a health check-up prior to air travel and avoid such travel if they have experienced chest tightness, breathlessness or arrhythmia in the 6 weeks leading up to their travel date. If air travel is essential, patients should wait at least 2–3 weeks following such symptoms before traveling. However, they should only do so after consultation with a doctor and once the airline has been informed of the issue.
2. Coronary Artery Bypass Grafting
   Since air may accumulate in the chest cavity after this form of surgery, it is recommended to wait for that air to be completely absorbed before flying or wait for 2 weeks after the procedure. It is also important to prepare enough medication in the carry-on bag for the trip, with detailed information and instructions on how to use each type of medication written down in case it is necessary to purchase them in cases where that medicine is lost.
3. Hypertension
   Patients with hypertension can travel by air as long as their condition is managed using medication. Any medication required during air travel should also be prepared prior to flying.
4. Venous Thrombosis
   This is classified into two types: deep vein thrombosis (DVT), which often occurs in the legs, and pulmonary embolisms (PE), which occur when a blood clot travels through the bloodstream and blocks the veins in the lungs. Airplane passengers often experience DVT in calf muscles. According to a study by the WHO, the risk of DVT increases by 2 to 3 times after being on a flight lasting more than 4 hours.
5. Asthma
   Airplane travel should be avoided in severe asthma cases that are unmanageable or for patients who have just been released from a hospital. In less severe cases and where medication can be carried, especially inhalers, air travel poses no problem.
6. Chronic Obstructive Pulmonary Disease
   These patients tend to experience hypoxia, so they should carry bronchodilator medication on their person and be sure to inform a member of airline staff in case emergency equipment is required on the flight.
7. Pneumothorax
   This is a condition characterized by trapped air in the pleural cavity, causing abnormal breathing. If it is necessary to travel by plane, it is recommended that patients with this condition first see a doctor to insert a tube to release the trapped air from the lungs. After that, the lungs should be allowed to fully expand for at least 7 days, as confirmed by a chest X-ray or CT scan, before traveling.
8. Infectious Diseases
   The nature of these diseases means they can be easily spread or transmitted to others, so traveling by airplane is prohibited. This is because the transmission of the infection can occur among passengers seated in the same area of the aircraft, which often results from coughing or sneezing by an infected person or through physical contact. To reduce the risk of infection transmission, patients should postpone travel until they have fully recovered from their illness.
9. Cerebrovascular Disease
   Various conditions can affect the blood supply to the brain, including transient ischemic attacks, intracerebral hemorrhages, and stroke, which can result in reduced oxygen supply to brain cells. Flying in an airplane with a reduced oxygen supply could exacerbate these conditions, so consulting a doctor before traveling is advisable in order to discuss the medication and necessary precautions to be taken while on the flight. Symptoms must be stable for at least two weeks before traveling.
10. Epilepsy
    Epilepsy has a higher chance of causing seizures in situations where there is a lack of oxygen, or when the patient is experiencing fatigue, weakness, anxiety, and changes in sleep patterns. Patients should therefore consult a doctor to prepare the necessary medication or possibly increase its dosage to keep the condition under control while traveling. Patients should wait at least one week following a seizure before they travel.
11. Anemia
    This condition is characterized by a lower-than-normal amount of red blood cells, which leads to a decreased delivery of oxygen to cells and tissues. This poses a risk of oxygen deficiency during flights. In cases where the concentration of hemoglobin is less than 10g/dL extra caution should be taken, and patients should not board a plane if their hemoglobin level is less than 7.5g/dL.
12. Diabetes
    Although the conditions inside an airplane cabin pose no danger to diabetic patients, crossing time zones can cause confusion in terms of meal and medication schedules, as well as the type of food that may affect their condition. Diabetic patients should therefore contact the airline to prepare diabetic-friendly meals and bring medication on board, including oral as well as any necessary intravenous medication and associated apparatus. Diabetic patients are advised to adhere to the schedule they followed before departure and then gradually adjust it to suit the new time zone.
13. Psychiatric Disorders
    Patients with psychiatric disorders should seek clearance from the doctor in charge of their treatment before flying to ensure the safety of themselves and other passengers. The doctor may prescribe sedatives that can be used during air travel.
14. Recipients of Recent Surgery
    Surgical procedures or injuries may involve residual air or gas, such as abdominal or gastrointestinal surgeries, craniotomy and facial surgeries, or eye surgeries. Patients who have recently undergone surgery should consult the doctor in charge of their treatment regarding how long they should wait before traveling by airplane.

In addition to those experiencing illness or injury, pregnant women and young infants are also considered at-risk groups when flying. Infants under 48 hours old are not allowed to fly. Instead, it is advisable to wait until the infant is at least one week old, in order to allow the body to become stronger and more resistant to disease.

As for pregnancy, although flying is not dangerous for the pregnancy or the unborn child, changes in atmospheric pressure during the journey may trigger a premature birth, especially if the pregnancy is beyond 36 weeks or within 4 weeks of the due date. Women at this stage of their pregnancy are therefore advised not to fly, except for domestic travel of around 1-2 hours and where no abnormal symptoms or complications from the pregnancy are present.

People who have been deep-sea diving should not board an airplane within 12 hours of their last dive and should wait at least 24 hours if they have dived multiple times. This is because the air pressure in the cabin of an aircraft at high altitude is lower than the pressure at sea level, which can cause a decrease in the oxygen in the blood, leading to oxygen deprivation and the expansion of gases in the body. This can cause ear pain, sinus pain, chest discomfort, or even decompression sickness.

1. Hypoxia
   When traveling on a plane the density of the air decreases, which causes the oxygen level in the blood to drop below normal levels. Hence, blood cannot deliver enough oxygen to the various muscles around the body, resulting in a range of potential symptoms such as coughing, changes in skin color and abnormal breathing. However, when a plane is flying at 30,000 feet the air pressure in the passenger cabin is adjusted to that of air at 5,000-8,000 feet, a height at which there is just a 15% reduction in oxygen compared to sea level. This is not dangerous for people who are healthy, but for patients with certain diseases such as heart disease, asthma, chronic obstructive pulmonary disease (COPD), anemia and epilepsy it may exacerbate symptoms.
2.  Effect of Barometric Pressure Changes
   During a flight’s ascent, atmospheric pressure decreases causing gases to expand. Conversely, when descending, air pressure increases causing gases to contract. These changes in air pressure can have many effects on the human body, depending on the type of gas involved, including:
   • Trapped gas in various parts of the body, such as in the middle ear, sinuses, stomach, intestines, teeth, and lungs. As the gas expands and contracts, it can cause symptoms such as ear pain, sinus pain, tooth pain, chest tightness, and abdominal discomfort.
   • Evolved gases are gases that dissolve in body fluids such as blood, synovial fluid, cerebrospinal fluid and fat. They mainly consist of nitrogen which can form bubbles when the air pressure decreases during ascent, causing symptoms such as joint pain, chest discomfort, and even neurological symptoms. 
3. Low Humidity
   Humidity levels in airplane cabins will be less than 20%, which is lower than normal levels (over 30%) on the ground. Low humidity can cause dry skin and discomfort in the eyes, mouth, and nose, but it is not dangerous to health. To overcome this, using moisturizing lotion for the skin and spraying saline solution in the nose are recommended, while wearing eyeglasses instead of contact lenses can help alleviate or prevent eye discomfort. There is no evidence to suggest that low humidity causes dehydration, so it is not necessary to drink more than usual. However, because caffeine and alcohol have diuretic effects, limiting the consumption of these beverages during long flights is advisable.
4. Decreased Mobility
   Sitting on an airplane for long periods can lead to swollen feet due to the decreased circulation to the legs that prolonged sitting can cause. Risks involved with this decreased circulation include inflammation of the legs and feet, aneurysms and thrombosis.
5. Air Sickness
   Air sickness is caused by the body’s response to flying, with symptoms of this condition differing with each individual and their familiarity with air travel.
6. Jet Lag
   ​​​​​​​Jet lag refers to a group of physiological symptoms caused by disruption to the body's biological clock due to long-haul travel. It can cause indigestion and impair intestinal function, as well as lead to daytime sleepiness, difficulty sleeping at night and reduced physical and mental performance. Jet lag gradually subsides as the body adjusts to the new time zone.

Preparing adequately for cross-continental long-haul flights can result in a relaxing experience and reduce the impacts on health. The following advice should be adhered to when preparing for long-haul air travel:

• Get plenty of rest before the date of your flight and seek out opportunities to nap (no longer than 40 minutes at a time) during the journey as this will ease tiredness.
• Exercise regularly.
• Select a suitable flight schedule; for instance, when flying for more than 12 hours at a time, select an onward flight that will give you enough time to get to the gate on time, stretch your legs, and relax properly before taking off again.
• Select an overnight flight.
• Prepare items that you will need during your flight, especially with regard to medication that must be taken during the journey.
• Wear comfortable clothes during your flight, ensuring they are also suited to the weather conditions at your destination.
• Regularly attend health check-ups. Those with underlying health conditions should consult their doctor prior to travel to ensure they are physically prepared for their flight, including having access to medication and being aware of factors that may exacerbate their condition or cause an in-flight emergency.
• The WHO recommends that passengers on board airplanes get up and walk around the cabin or visit the bathroom every 2–3 hours during long-haul flights to reduce the likelihood of DVT. They also advise against passengers placing baggage at their feet as this may restrict movement, which is necessary to keep blood circulated to the feet and legs.
• Those who experience air sickness should ask to sit toward the middle of the cabin and pack medication that can alleviate sickness, such as a peppermint field inhaler, in a carry-on bag, keeping it close at hand throughout the flight.
• Eat small meals and limit the consumption of alcohol, caffeine, or heavy meals for at least 4–6 hours prior to flying as this will help you sleep on the plane.
• Get plenty of rest and sleep in the 24 hours leading up to the flight, with at least 4 hours of sleep considered healthy, as this will give your body the best chance of adjusting to its new time zone quickly.

• Patients with underlying health conditions should consult a doctor before traveling and prepare their regular medication to bring on board the plane. If patients have artificial joints, a pacemaker, or require medical equipment on board, a doctor's certificate must be carried.
• Patients who need to take medication on a strict schedule, such as insulin or birth control pills, should seek advice from a doctor before traveling.
• Disabled passengers who require assistance during the flight should have a traveling companion and inform the airline in advance.
• Patients who have received treatment for a chronic condition or who may experience a deterioration of their condition during travel should submit a medical information form (MEDIF) to the airline before booking their seats. They should also specify the amount of oxygen required on the flight and any other necessary assistive devices.
• Infants under 7 days old and premature babies must submit a MEDIF to request approval for travel.
• Pregnant women without health complications who are over 28 weeks pregnant must have a doctor's certificate stating their due date and certifying their safety for travel. They are not permitted to fly after 36 weeks of pregnancy.

 Air travel involves several factors that could impact the health of passengers, while there are also certain medical conditions that can affect passenger safety and convenience during air travel. Therefore, patients with underlying health conditions, pregnant women, young infants, and people who have recently been deep-sea diving should consult with their doctors to understand the risks that may arise from traveling by airplane. Different airlines have different policies, so it is always important to check their regulations before booking a flight and find ways to make the travel safe and comfortable for yourself, other passengers, and crew members.