Can Flying Make You Sick?
Can riding on an airplane make you sick? Not likely.
Can what you do while traveling make you sick? Perhaps.
Can you do anything to make it less likely that you will get sick when on the road? Definitely.
Many health problems ranging from colds to tuberculosis to blood clots have been linked to air travel in news reports lately. But that doesn't mean you're likely to come down with one of those conditions on the road. You can stay healthy while traveling.
DON'T SIT SO CLOSE TO ME
Many people believe ventilation systems on planes circulate germs, raising the likelihood they will catch colds when traveling by air. The reality is they have a lot more to worry about with the people sitting nearby than from the person sniffling and hacking away 10 rows back.
Researchers have studied the transmission of colds and tuberculosis, a highly contagious lung disease, among travelers sharing long airplane rides. After a passenger with a drug-resistant strain of tuberculosis traveled from Honolulu to Baltimore and back, researchers tracked down those who flew on the same flights as she did. They found that passengers seated within two rows of the sick passenger were more likely to have positive skin tests for TB than passengers in the rest of the plane were. Other passengers who tested positive for TB had other risk factors for the disease (for example, some were health care workers), making it impossible to determine whether they had become infected while traveling.
The Centers for Disease Control and Prevention investigated another incident in which passengers became infected with TB during a long flight. The CDC concluded that transmission occurred because the passengers were seated near the infectious traveler, not because bacteria spread through the air circulation system. (Note: Infection with TB doesn't mean you will come down with the disease; it just means you'll need preventive medication.)
Older airplanes circulate fresh air in the passenger cabin, but newer planes rely on recirculated air. Planes that use recirculated air commonly use HEPA [high efficiency particulate air] filters, which remove microscopic particles in the air. These are the same filters that many hospitals use in operating rooms.
In light of the increased use of recirculated air, researchers recently looked at transmission of the common cold in airplanes. They surveyed 1,100 passengers traveling from San Francisco to Denver between January and April 1999. About half the passengers traveled on newer planes that used recirculated air, the rest on older planes with fresh air systems. Passengers traveling on both old and new airplanes had similar rates of colds within a week of flying, so researchers concluded that the type of air circulation is not related to the incidence of colds. In other words, germs from the back of the plane are not blowing to the front, and vice versa.
About 20 percent of passengers in both groups, however, reported cold symptoms, more than one might expect in the general population. Adults average two colds per year, and most colds occur during the months in which the study was conducted. About 3 percent to 5 percent of the population has a cold at any given time. What accounts for the higher prevalence of colds in those travelers?
The confined quarters of the plane make it easier to transmit germs among passengers who are seated near someone who is already ill, the researchers concluded. Moreover, the jet lag, poor diet and sleep deprivation associated with travel all lower resistance to disease.
SHAKE A LEG
"Economy class syndrome," or deep vein thrombosis (DVT), consists of blood clots in the legs that can form when people with underlying cardiovascular conditions sit still for too long. The clots themselves are not a problem, but they can break off and travel to the lungs, a life-threatening condition called pulmonary embolism. Symptoms include leg pain, dizziness, chest pain and shortness of breath.
Most healthy, active people are not at risk for pulmonary embolism when flying.
A study of more than 135 million passengers who arrived at Paris' Charles de Gaulle Airport last year from 145 countries or regions found 56 cases of pulmonary embolism among the passengers who required transport to a hospital. Only three of the patients said that they had left their seats at some point during the flight. Even though the researchers may have underestimated the incidence of blood clots (they looked only at passengers who fell ill while still in the airport, not those who went to the hospital later), the risk still appears to be small-in this case, 0.4 cases of pulmonary embolism per million passengers.
Certain people are more susceptible to DVT than others and should consult a physician to assess the risk of blood clots, particularly on flights of six hours or longer. They include people with varicose veins, a family history of DVT, or blood clotting disorders; older travelers (over age 50 or so); women on birth control pills or hormone replacement therapy; smokers; and anyone who is seriously overweight. Ways to avoid DVT include staying hydrated, wearing loose clothing, not crossing your legs, changing position often, getting up and walking, and moving your legs while seated.
According to James Whinnery, manager of aeromedical research at the Civil Aeromedical Institute in Oklahoma City, "Only the people who fly the most need to worry [about DVT]. Someone who sits for a long time would always be at risk. It's not the aircraft."
Even though DVT is not common, it occurs enough that the World Health Organization and the International Civil Aviation Organization are studying the problem. Their research will assess the frequency of DVT among travelers; identify which groups are most at risk; and look at possible causes, such as low cabin air pressure and oxygen levels.
IT'S STUFFY IN HERE
The Association of Flight Attendants, the Federal Aviation Administration, and others are concerned that poor air quality in airplanes may contribute to health problems. For example, insecticides, ozone and vapors from lubricants, de-icing solutions and hydraulic fuels all can leak into cabin air. The chemicals can have serious health effects, but it is not known whether they create problems for travelers at the concentrations found in cabin air.
In addition, cabin air is pressurized to levels found at 8,000 feet-basically, you're on a mountaintop. Even though the concentration of oxygen in the air is the same as at sea level, less oxygen is available to the body because of the lower air pressure. Moreover, carbon dioxide (CO2) levels in the passenger cabin can be higher than in ordinary, ground-level air, the result of so many people sitting in close quarters. High CO2 levels-that stuffy feeling-can lead to headache, drowsiness and dizziness.
"If you have any compromise in your oxygen-carrying capability, you can be affected by even small fluctuations" in CO2 and air pressure, Whinnery says. Older people, particularly those with cardiovascular problems, and infants are especially susceptible to such fluctuations. Again, consult with a physician before flying.
Cabin air is not just stale-it's dry. Consequences of very low humidity include dry eyes, dry skin, irritation of the nasal passages and dehydration. Most people find that the discomfort ends shortly after landing.
In December, the National Research Council issued a report on cabin air quality. It made 10 recommendations, one of which was that the FAA demonstrate that federal regulations on cabin air quality are adequate. The FAA is working with the National Institute of Occupational Safety and Health to study the relationship between cabin air quality and health.
HERE'S TO YOUR HEALTH
Most people experience no ill effects from flying, even those who travel often. Jet lag from time zone changes and existing health issues are more likely to create complications for travelers. Air travel is so common and health problems are so infrequent that most people (except pregnant women) don't think to consult a physician before flying. But if you have concerns, consult your doctor. That way, you can rack up those frequent flier miles with confidence.