There are roughly 5,000 planes in the sky over the United
States at any given moment, according to the National Air
Traffic Controllers Association. On board many of these planes
are passengers who are on their way to a business meeting,
vacation or to visit family or friends.
Up to 90 percent of travelers who cross a time zone
during their flight experience the symptoms of jet lag.
But after your ticket has been purchased, your bags are packed,
and you're sitting on-board, waiting for takeoff, there is
something you should know. While most people fly safely without
any problem, flying does carry with it very real health effects
-- and you may be at risk.
Health Risks of Long, and Short, Flights
Deep Vein Thrombosis (DVT) (Long Flights)
DVT, also known as 'economy class syndrome,' is a blood clot
that develops as a result of being immobile for a long period
Studies by the World Health Organization found that, indeed,
if you sit immobile for four hours or more (on a plane, bus,
car, etc.) your risk of getting a blood clot called a venous
thromboembolism (VTE) doubles. Though DVT is sometimes called
economy class syndrome because it's more common in the cramped
quarters of economy class, experts want the nickname removed
because first-class travelers are also at risk.
The risk of developing VTE after four hours of being seated
is still relatively small at about one in 6,000.
VTE occurs because blood stagnates in your veins when you're
seated. VTE usually leads to DVT, which is when the blood
clot occurs in a deep vein, typically in the lower part of
DVT can cause pain and swelling, but becomes life threatening
if part of the clot breaks off and travels to your lungs.
This is called a pulmonary embolism, and it can block your
blood flow and be fatal.
Breaking up your flight into several, shorter ones, does
not reduce the risk because your risk of VTE remains increased
for about four weeks after you fly. So the more you fly in
a short period of time, the more your risk accumulates. Other
factors that increase your risk of VTE include:
Being very tall (over 6'3") or very short (under
Using oral contraceptives (birth control pills)
Certain blood disorders that increase your clotting tendency
What can you do to reduce your risk? Wear loose-fitting clothing,
move your feet and calf muscles often, and get up and walk
around as much as possible during the flight. You can also
find elastic compression stockings at most pharmacies that
you can wear during the flight. They're designed specifically
to reduce the risk of DVT.
You can reduce the "side effects" of air
travel by drinking plenty of water during your flight,
avoiding alcohol, and walking around the plane as much
During long flights, aircraft cabins are typically pressurized
to 8,000 feet above sea level, which although typically not
high enough to cause actual "mountain sickness,"
can certainly cause a lot of discomfort (if you've ever visited
Denver, CO, which is 5,280 feet above sea level, you'll know
what this feels like). (Shorter flights are typically pressurized
at 5,000 to 6,000 feet.)
A study published in the New England Journal of Medicine
found that upon participating in a 20-hour simulated flight
pressurized at various ranges above sea level, oxygen saturation
was lowered by about 4 percent.
This did not cause adverse health effects, but it did cause
discomfort in a lot of the passengers after three to nine
hours in flight in a cabin pressurized to 8,000 feet. Symptoms
included malaise, muscular discomfort, fatigue, and ear, nose
and throat discomfort.
What can you do? Drinking a lot of fluids (non-alcoholic
varieties) and moving around as much as possible may help
to relieve some discomfort.
Up to 90 percent of people who cover long distances in flight
may feel the effects of jet lag. Jet lag occurs when you cross
multiple time zones and your body clock, or circadian
rhythm, becomes out of sync with the actual time. It can result
in fatigue, insomnia, disorientation, headaches, lost appetite,
stomachaches, and feeling "out of it."
It can take a full day for each time zone you've crossed
for you to fully recover.
What can you do? Avoid alcohol the day you're going to fly,
drink plenty of water during your flight, and get a good night's
sleep before your flight. When you reach your destination,
try to adjust to its time zone as quickly as possible by sleeping
and eating at the appropriate times.
About 50 percent of the air in aircraft cabins is re-circulated,
which, along with the close proximity to other passengers,
brings up the possibility of transmitting infectious diseases.
In reality, experts believe the risk of airborne infections
is actually very low, perhaps lower than the risk in an office
building or public bus or train.
It is, however, possible to contract diseases such as meningitis,
measles and tuberculosis.
What can you do? Wash your hands often (especially before
eating), don't touch your mouth or eyes unless your hands
are clean, and, if you're seated near someone who appears
to be sick, ask to move to another seat.
of Flying: How to Get Over Your Phobia of Flying in an Airplane
Steps to Take if You Ever Experience the Frustration of Lost
Air Traffic Controllers Association
Health Organization: WRIGHT Project
New England Journal of Medicine Volume 357:18-27, July 5,
2007, Number 1
October 9, 2006