Travel

Staying healthy on layovers

October 12, 20269 min readFor pilots and passengers

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In this article

Dry air, and how much it really dries you out
Blood clots on long flights
Food and water abroad
Sun, at altitude and on the beach
Mosquitoes and other bites
Travel vaccines
Moving, eating and sleeping
Getting help on the road
How LogAloft helps

Flying for a living puts your body in an odd place: dry air at the equivalent of a mountain town for hours at a time, long stretches sitting still, meals at strange hours in cities with different germs, and more sun, at altitude and on layover afternoons, than most office workers get in a year. None of it is dangerous on its own, and most of it is easy to manage once you know what the evidence says. Below is what the CDC, the WHO and the FAA say about each, and the habits that follow.

This is general information, not medical advice. For your own health, see your doctor, and if you're a pilot, check any medication with your aviation medical examiner (AME).

Dry air, and how much it really dries you out

Airliner cabins are pressurized to the equivalent of 1,830 to 2,440 m, about 6,000 to 8,000 ft, according to the CDC Yellow Book, and the air is "typically dry, usually 10–20% humidity," which can dry the airway and the eyes. The air itself is cleaner than its reputation: it's refreshed 20 to 30 times an hour, and the recirculated part passes through HEPA filters that capture 99.97% of particles.

Does the dry air dehydrate you? Less than people think. The US National Research Council's review of the cabin environment found that low humidity "may cause drying of the skin, mucous membranes, and conjunctivae," but cited a study in which water loss over 7 hours was insignificant, and concluded the effects are probably temporary. The dryness is mostly a comfort problem: sore eyes, a dry nose, cracked lips.

What helps:

Drink water through the flight instead of catching up at the end. A bottle at your seat or in the flight deck is easier to keep up with than waiting for the cart.
Eyes and nose. Lubricating eye drops and a saline nasal spray help on long legs.
Skin. A plain moisturizer and lip balm.
Alcohol. For pilots, the FAA rule is 14 CFR 91.17: no flying within 8 hours of drinking alcohol, while under its influence, or with a blood alcohol concentration of 0.04% or more, and many airlines set stricter limits.

Blood clots on long flights

Long periods of sitting slow the blood in the legs, and in some people a clot forms in a deep vein (deep vein thrombosis, DVT). If part of it breaks off and reaches the lungs, it's a pulmonary embolism. Together they're called venous thromboembolism (VTE).

The CDC Yellow Book chapter on DVT puts the numbers in proportion:

On flights longer than 4 hours, one study found an absolute risk of 1 in 4,656 person-flights; another found about 1 in 6,000.
Long-distance travel might raise a person's overall risk 2- to 4-fold, "but the data are inconsistent."
On flights under 4 hours the risk of a clot with symptoms is negligible.
Most travel-related clots appear in the first 1 to 2 weeks after the flight, and the risk is back to baseline by 8 weeks.

Most people who develop one have at least one other risk factor: active cancer, estrogen use (including the pill and hormone therapy), recent surgery, hospitalization or injury, limited mobility, a BMI of 30 or more, age over 40, pregnancy or the weeks after it, a previous clot, an inherited clotting tendency, or a family history. Height matters at both ends: under 1.6 m (5 ft 3 in) or over 1.9 m (6 ft 3 in).

Prevention, per the CDC:

Walk around and exercise your calves during the flight. Crew moving through the cabin do some of this naturally; pilots on long legs and crew on breaks or deadheading should get up regularly.
Choose the aisle when you deadhead or travel. Window-seat travelers had about twice the risk, and about six times with a BMI of 30 or more.
Compression stockings if you're at higher risk: for flights over 6 hours, the American College of Chest Physicians suggests properly fitted below-the-knee stockings giving 15 to 30 mmHg at the ankle.
Not aspirin by default. The same guidance advises against aspirin or anticoagulants just for travel, unless your doctor recommends them because your risk is substantially higher.

Know the signs. For a DVT: pain or tenderness, swelling, warmth, and redness or discoloration over the area, usually in one leg. For a pulmonary embolism: unexplained shortness of breath, chest pain that's worse when you breathe in, coughing (sometimes blood) and fainting. A pulmonary embolism is an emergency. Get help right away.

Food and water abroad

Travelers' diarrhea is common: depending on the destination and season, the CDC puts attack rates at 30% to 70% of travelers over a two-week trip. Bacteria are the most common cause.

The CDC's food and water advice where sanitation is a concern comes down to a short list:

Usually safe	Avoid
Food that's fully cooked and served hot	Salads, raw vegetables and unpeeled fruit
Fruit you rinse with safe water and peel yourself	Raw or undercooked meat, fish, shellfish and eggs
Pasteurized milk and dairy	Unpasteurized milk, dairy and fruit juice
Commercially bottled water from a factory-sealed container	Tap water and ice, unless you're reasonably sure the water was safe
Tea and coffee made with water that was just boiled	Food and drinks from street vendors, which raise the risk

Wash your hands before eating, or use a hand sanitizer with at least 60% alcohol. Sanitizer is not as good as soap and water against some germs, such as norovirus.

If you get sick, pilots have a medication problem. The usual remedy, loperamide (Imodium), is on the FAA's "no go" list of over-the-counter medications because it can cause sedation and dizziness and can mask the underlying illness. Bismuth subsalicylate (Pepto-Bismol, Kaopectate) is on the "go" list. After a "no go" medication, the FAA's guidance is to wait at least five dosing intervals after the last dose before flying: 30 hours for a medicine taken every 4 to 6 hours, 60 hours for one taken every 12. Oral rehydration solution is the CDC's choice for real fluid loss. For severe illness, with fever or blood, see a doctor; antibiotics are a prescription decision, and pilots should check them with their AME. And if you're sick, you're not fit to fly. Call in.

Sun, at altitude and on the beach

UV radiation grows stronger with height: the Hong Kong Observatory puts the increase at about 12% for every 1,000 m. At cruise, the question is how much gets through the windows.

In a small study published in JAMA Dermatology in 2015, researchers measured UV in the cockpit of a turboprop at 30,000 ft. The windshield blocked UVB completely, but UVA came through, and 56.6 minutes at that altitude gave about the same carcinogenic UVA dose as a 20-minute tanning-bed session. It was one aircraft, measured around midday in April, and the authors note levels could be higher over thick clouds and snow fields, which reflect up to 85% of UV. The CDC's NIOSH summarizes the bigger picture: glass windshields block most UVB but only a little under half of UVA, plastic ones block most of both, and it isn't known how much cabin windows block across all airliners.

A 2015 meta-analysis of 19 studies with more than 266,000 participants found about twice the expected rate of melanoma in pilots and cabin crew. NIOSH says plainly that nobody knows for sure why: more sun in flight is one possibility, more sun off duty is another. Both are worth protecting against:

In the flight deck: sunscreen on the face, neck and hands on daytime legs, the visors down, and sunglasses (they protect your eyes, too).
On the layover: the WHO recommends protection whenever the UV index is 3 or higher: shade around midday, a shirt, a hat, sunglasses and sunscreen, and staying in during midday hours at 8 or above. Many weather apps show the UV index.
With insect repellent: apply sunscreen first, then repellent, as separate products.
Check your skin, and see a dermatologist about any mole that changes.

Mosquitoes and other bites

Where mosquitoes carry dengue, malaria or other diseases, repellent is the first line of defense. The CDC lists the active ingredients that give reasonably long-lasting protection: DEET, picaridin, oil of lemon eucalyptus (or PMD), IR3535 and 2-undecanone. Permethrin goes on clothing and gear, never on skin, and has to be applied 24 to 48 hours before packing so it can dry. Long sleeves at dawn and dusk, and a room with screens or air conditioning, do the rest.

Travel vaccines

Being up to date on routine vaccines is the base. The CDC advises seeing a health care provider at least 4 to 6 weeks before a trip, because some vaccines need more than one dose, and its destination pages list what's recommended country by country. Crews who bid new destinations, or get them by reserve, can't always plan that far ahead, so it's worth reviewing your airline's route map with a travel clinic once rather than trip by trip.

Yellow fever is the one where paperwork matters too. Some countries require proof of vaccination to enter, recorded on the International Certificate of Vaccination or Prophylaxis (the yellow card), and the vaccine has to be given at an authorized center. Since July 11, 2016, under the International Health Regulations, that certificate is valid for the life of the person vaccinated, and a country can't refuse it because more than 10 years have passed. Keep it with your passport.

Moving, eating and sleeping

The WHO recommends that adults get at least 150 minutes of moderate activity a week (or 75 of vigorous activity), plus muscle-strengthening work on at least 2 days. A layover gives you the time but not always the routine. A 30-minute walk in daylight after landing, a hotel gym session or a bodyweight routine in the room adds up over a trip, and daylight at the right time also helps your body clock settle. When to seek light, and when to avoid it, depends on which way you flew; Jet lag east and west explains how.

Meals work best fitted to the hours you'll actually be awake, not to three meals by the local clock. And sleep is the foundation the rest stands on: Rest is not sleep covers why a 10-hour rest can turn into 6 hours of sleep and how to plan around it.

Getting help on the road

If you need a doctor abroad, the hotel can usually call one, your company's medical or crew support line can direct you, and US citizens can contact the US embassy or consulate for help finding medical care. Carry a short list of your medications and allergies, and check that your health insurance covers you abroad.

How LogAloft helps

Every layover in Coming up gets a Rest plan: when to be in bed, how long a nap on arrival should be, meals fitted to the hours you're awake, optional exercise, daylight to seek and light to avoid on longer trips, and when to start getting ready. The Rest plans and jet lag guide explains how it's built. It's a plan, not medical advice, and it doesn't replace your doctor, your AME or your company's fatigue policy.

Sources

This is information, not medical advice. For questions about your own health or a pregnancy, talk to your doctor or aviation medical examiner.