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 / Updated  / Source: Today
By TODAY

Heading home for the holidays? So is the rest of the country — according to the American Automobile Association (AAA) over 54 million Americans will be traveling for the Thanksgiving holiday. And if you're hoping to stay healthy during your flight, you might want to take a few cues from Dr. Judith Reichman, a women's health expert. Here, she answers top questions about holiday travel.

Why do those who fly frequently complain of headache, fatigue, fever or breathing problems?

Some of these symptoms may be due to the low barometric pressure, oxygen content and humidity in the air cabin. When combined with jet lag, sleep deprivation, stress, (security concerns, long lines, missed flights, delayed and cancelled flights), as well as cramped seating, motion sickness and discomfort from vibration and engine noise, we have ample reason to feel “ill.” And let’s not forget that engine fumes can, on occasion, seep into the cabin.

Is the closed environment of an airplane a repository for germs?

Not necessarily. In order to address the question, we have to understand how the aircraft cabin is ventilated. Once in flight, the air from the outside (which should be sterile at higher altitudes) is vented through the engines where it is heated, compressed and subsequently cooled. It then flows into the plane from overhead air vents, circulates across the aircraft and exits from the floor of the cabin. The airflow is laminar, or side-to-side. This means it flows from top to bottom in lateral sections, not from front to back.

Usually about 50 percent of the air is re-circulated, and as this happens, it passes through very special air filters, which remove dust, vapors, bacteria and mold. Although a virus would be too small to be trapped by the filter, we know that viruses are usually attached (or spread by) droplets. And these are removed by the filters.

In a report to the House Subcommittee on Aviation, experts stated that “data from epidemiologic studies and microbiologic assays indicate that the risk of airborne infections currently appears to be very low.” And an independent published research showed that the concentration of biological microorganisms in planes is lower than in an office building, an ordinary city street and on public buses or trains.

So is there an infection risk for passengers?

Even if the air is appropriately circulated there are however, ways that infections can be transmitted to passengers. These two modes of transmission will account for the greatest risk of infection:

Contact infection: This occurs from body-to-body contact or from large droplets that are sprayed several feet when an infected person sneezes, coughs or talks. The virus or bacteria sprayed at you then enters your body and infects you through your eyes, nose or mouth.

Airborne infection: This occurs when larger infected droplets partially evaporate. The residue or smaller droplets become widely dispersed in the air and remains there until the air is exchanged or appropriately filtered.

These risks, however, are dependent on how infectious the “sick” person is, the proximity of his seat and duration of the exposure. (Flights over eight hours appear to be of greatest risk.)

Which diseases are most likely transmitted through cabin air?

The common cold: Believe it or not, there are very few published reports of cold outbreaks as a result of air travel. That may be due to the fact that colds are so common that it’s difficult to compute whether they were “caught” on a plane.

Also the decrease in the humidity of airplane air with subsequent drying of nasal passages, fatigue and proximity to someone who is sneezing and coughing are variables that affect a person’s susceptibility and the likelihood of infection with cold viruses. But “infected” plane air is probably not to blame; a study of the percentage of fresh air, which was re-circulated in the cabin (50 percent versus 100 percent), showed that it made no difference in the development of upper respiratory tract infections.

Influenza: We know that air travel allows individuals from one area of the world to spread a specific type of flu to another and indeed, air travel is probably the chief cause of global spread. But there is less concern about actual in-flight transmission, unless the aircraft is grounded with an inadequate ventilation system. The best way to decrease your chances of infection is to get your flu shot, and remember, immunity occurs two weeks after the vaccine, so plan ahead. Other airborne diseases:

Meningitis: There were 21 reports of suspected travel associated meningitis cases that occurred between 1991 and 2001. It was felt that these were contracted as a result of close proximity of passengers to an on board contagious individual.

Measles: This too is very contagious and the latest known airborne infection occurred in 2002 when children from an orphanage in China were brought to the US and apparently were contagious at the time of their flight.

What about food and water contamination?

Microorganisms that cause food poisoning and gastroenteritis diseases usually are spread by contamination of food or water. These include salmonella, staphylococcus, cholera and a virus called Norwalk-like agent. No food-borne or water-borne outbreaks have been reported over the past few years, probably because the food is often pre-packaged and frozen.

The water in on-flight tanks, especially if filled from water sources which are less than “pure” may be contaminated. Long or repeated storage within the tank can, despite best efforts, result in bacterial growth. If you don’t want to drink the water in the country from where the flight originated, don’t drink the water from the plane tank. Bottled water is always the safest way to maintain hydration.

What about the dry air?

The humidity within the cabin is usually below 25 percent, and can definitely cause sinus and mucous membrane discomfort. We would probably feel better if the humidity was 35 percent (that’s what it is in a comfortable home environment), but increasing humidity can also encourage growth of bacteria and fungi, especially in the aircraft water tanks; hence the airline industry has hesitated to do so.

What can we do to stay healthy when we fly?

Respect others: Don’t fly if you are sick. Aside from concern for the other passengers’ health, flying with an ear, nose or sinus infection and/or severe congestion, may cause obstruction of airflow in your middle ear and sinuses during takeoff and landing. This in turn can cause severe ear and sinus pain and injury to the eardrum.

Prevent dehydration: Drink plenty of water (and make sure your children do this, they are especially susceptible to dehydration.) If you want to ensure that the water you drink is not contaminated, ask for bottled water. Don’t add ice cubes if they are made from water that could be unsafe. Drink tea and coffee only if the water used to make it is boiled or is bottled.

Limit caffeine and alcohol: These add to dehydration and jet lag.

Prevent dryness of your skin, eyes and airways: Use moisturizer, saline eye drops (or rewetting drops) for contact lenses and saline nasal sprays.

Practice good hand hygiene: Wash your hands before you eat. Don’t put your unwashed hands in your mouth or rub your eyes. Move. If someone nearby seems sick, ask if you can move to another seat. And don’t forget, even if you are surrounded by healthy individuals, it’s important to get up, move and stretch to prevent blood clots and deep veined thrombosis (DVT).

Should you wear a mask?

The use of masks to prevent infection within the aircraft carrier is unproven. The bottom line? Work, recreation and families have become global. Most of us have to fly. With rare exceptions, we don’t risk serious illness. Simple hygiene, hydration and judgment can help prevent air related health problems.

Dr. Judith Reichman is the author of "Slow Your Clock Down: The Complete Guide to a Healthy, Younger You."

PLEASE NOTE: The information in this column should not be construed as providing specific medical advice, but rather to offer readers information to better understand their lives and health. It is not intended to provide an alternative to professional treatment or to replace the services of a physician.