Researchers are finally starting to gather and publish more data about the health risks associated with airplane travel.

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With literally billions of people traveling by air every year now, researchers are finally starting to gather and publish more data about the health risks associated with airplane travel. In terms of the common cold, it is now well-accepted that acute respiratory infections are frequently experienced after air travel. So it’s no surprise when we find ourselves getting sick after flying.

Studies have found a high prevalence and wide array of respiratory viruses in people who have recently traveled.[2] Up to 20 percent of passengers may develop respiratory infections within one week after air travel and that flight attendants have significantly more respiratory infections than those who do not frequently fly.

Can Traveling Make You Sick?

So why does flying on a plane increase our susceptibility to getting sick?

• Spread of exhaled infected droplets. Airline cabins have lots of people in a crowded space who are there for long “exposure times,” so the risk of infection via airborne transmission could be high—especially if one or more passengers are infected with an airborne infectious disease. Droplets exhaled by an infected passenger may contain infectious agents such influenza. In fact, droplets have been shown to spread through the air from a single cough, a single breath, or a few seconds of speaking. Exposure to the row in front and the row behind occurs within 30 seconds and extends to seven rows within minutes.[3]
• Low air pressure and oxygen compromise immune function. The conditions of low air pressure and low oxygen have been shown to impair certain immune system functions for a few days after long flights.[4] Researchers, to test how typical airplane air pressure and oxygen levels affect the immune system, studied the effects of a simulated 10-hour flight at an average cruising altitude of 8000 feet and then measured markers of immune system function in 52 healthy volunteers. They looked at blood samples before and on days 1, 4, and 7 after the flight. The researchers observed a number of immune system changes in the immediate days following the simulated flight. For instance, the subjects’ lymphocyte responses were decreased. Lymphocytes include T cells, B cells, and natural killer cells. Lymphocytes are the primary type of white blood cells made by the immune system to combat viruses, bacteria, and other pathogens. These immune changes, they concluded, “may contribute to an increased susceptibility to respiratory infections commonly seen after long-haul flights.”[4]

Venous Thrombosis: Another Health Concern Tied to Air Travel

The lower oxygen levels and prolonged sitting on long flights doesn’t just impair your immune system’s ability to fight infections, it also puts you at risk for deep vein thrombosis and pulmonary embolism. Together, these two conditions make up the third most common cardiovascular disease after heart attack and stroke.

For persons who contract the conditions, they carry a high risk of death and permanent complications. Deep vein thrombosis is a condition in which a blood clot (thrombus) forms in one or more of the deep veins in your body, usually in your legs. Deep vein thrombosis can cause leg pain, but often occurs without any symptoms. Pulmonary embolism is a complication of deep vein thrombosis in which one or more arteries in your lungs becomes blocked by a blood clot that has traveled to your lungs from your leg.

While these conditions are of most concern for people with chronic respiratory diseases, doctors who specialize in travel medicine and lung diseases have been trying to spread the word for years that all travelers need to take precautions to avoid venous thromboembolism. This involves avoiding excess alcohol and caffeine-containing drinks, remaining mobile, and exercising during the flight.

For air travelers with a history of venous thromboembolism, obesity, heart disease, significant medical illness in previous six weeks, immobility, pregnancy, or estrogen therapy (hormone replacement  therapy or combined oral contraceptive pill), experts advise that in addition to the above advice, travelers wear compression stockings, avoid sedatives, and avoid sleeping for prolonged periods in abnormal positions. They also recommend a preventive dose of blood thinning medication for those at high risk of clots, such as those who have recently had a stroke, major surgery, or trauma.

How to Avoid Catching a Cold on a Plane: Three Strategies

To reduce your risk of getting a respiratory infection while on a flight, here are three specific actions you should take:

1. Irrigate your nose (or your children’s) with a saline solution—both before and after the flight—by using a dropper or small squirt bottle. Nasal irrigation with a saline solution helps clean out at least some of the allergen, fungal, and viral pathogens from the nose and thus can help to reduce the risk of getting a sinus infection after flying. Keeping the nasal cavity moist in the dry atmosphere of an airplane cabin is also most beneficial.
2. Drink lots of water throughout the flight.
3. Take an herbal medicine with immune-boosting properties such as Echinacea for a week or two before the flight. Australian researchers conducted a randomized, double-blind placebo-controlled trial to study whether a standardized Echinacea supplement is effective in the prevention of respiratory and other symptoms associated with long flights.[5] They gave 175 adults travelling for 15 to 25 hours Echinacea (root extract, standardized to 4.4 mg alkylamides) or placebo tablets starting 14 days before travel. The Echinacea group had lower respiratory symptom scores compared to placebo during travel. If you’re planning on traveling by air, you can give your own immune system a boost with Echinacea or other immune stimulating natural therapies starting at least two weeks before you travel. For more ideas on natural immune boosters for prevention of viral infections, such as Elderberry, Beta-Glucans, and Red Korean or American Ginseng, see our post “3 Immune System Supplements to Prevent the Flu this Winter.”