We've all walked off the plane with our throat parched, eyes dry, and skin lizard-like. Why does long-haul flying leave pilots and passengers feeling as if they just spent 40 days under the desert sun?
Quick Recap - What is humidity?
Humidity is the amount of water vapor present in the air. Although the humidity we all experience in our day-to-day lives varies depending on location, weather, and the time of year, most home's relative humidity is at least 30%. For optimal indoor air quality, the US Consumer Product Safety Commission recommends indoor relative humidity levels between 30% to 50%.
Airplane Humidity Levels
Airplane humidity levels are low from the standpoint of human comfort, often below 20% according to both the World Health Organization and Boeing. That aircraft cabin air is dry - for reference, humidity levels in the Mojave desert range from 10% to 30% during the day.
Why is airplane air so dry?
Commerical aircraft cruise at high altitudes, often between 33,000 and 42,000 feet. And, the relative humidity seven miles above the earth's surface is much lower than that on the group. Pressurized aircraft cabins also require the circulation of air. This recirculation process pulls in cold, dry air from the aircraft's cruising altitude. The air is then circulated throughout the cabin, resulting in low airplane humidity.
You might ask, "Why don't airplane's humidify the air?" The reason airplane cabins are not humidified is due to the immense weight of the water necessary to accomplish such a feat.
Ask any pilot - ensuring the aircraft's flying within weight and balance guidelines is critical for a safe flight. Water weighs 8lbs per gallon, and humidifying the cabin could require quite a bit of water. Aside from the fact excess water in the air could lead to corrosion, it isn't practical to carry thousands of additional pounds up to the aircraft's cruising altitude.
Combat Low Airplane Humidity
Dermatologist suggest low humidity impairs the skin's ability to retain moisture, which makes people feel dried out after an extended period of time in areas of low relative humidity. The World Health Organization suggests low humidity causes skin dryness and discomfort to the eyes, mouth, and nose. They note, however, that low relative humidity doens't present other health risks.
Use a Travel Humidifier
Although you may or may not be able to pull it out on the plane, travel humidifiers readily tuck into carry-on luggage and help alleviate symptoms caused by low airplane humidity. Adding a cool mist of water to the air while sleep can help keep your lungs, sinuses, and skin happy while you're living on the road.
Pick Shorter Routes
You're less likely to experience discomfort associated with low airplane humidity on flights below three hours. The National Institute of Health notes pilots, flight attendants, and passengers can attribute their "mucosal irritation" to low airplane cabin humidity on flights lasting three hours or longer.
Pilots and flight crew regularly embarking on trans-Atlantic flights may see signs of reptilian skin when deplaning. Including some moisturizer in your flight bag is always a good idea. Avoid cracking knuckles and dry-spots by using skin moisturizer on the hands and face before flight. Toss in some lip blam too if you don't want your "lips to hurt real bad."
Use Saline Nasal Spray
My private pilot flight instructor introduced me to Ayr Saline Nasal Sinus Spray early during my training. And, I've kept a bottle in my flight bag ever since. It helps restore moisture and relieve dry nasal passages due to, among many other things, low humidity.
As pilots, it's always best to carefully evaluate OTC medications and treatments. Check with your Aviation Medical Examiner before using any nasal sprays to ensure they won't inhibit your ability to act as pilot in command.
If you're not a pilot and seek relieve from low airplane humidity and dry air, check our Ayr.
Contact wearers on the flight deck appreciate the luxury of sunglasses - it's always sunny when you're up top. But pilots experiencing dry eyes may seek prescription eyeglasses and sunglasses rather than contact lenses. The World Health Organization suggests wearing eyeglasses rather than contact lenses helps relieve eye discomfort associate with low airplane humidity.
Avoid Caffeine and Alcohol
Although this goes without saying, pilots should always avoid alcohol before and during flights.
But, many pilots may not know caffeine causes a diuretic effect, more urine production. Enjoying a few cups of coffee before or during a long flight could lead to dehydration, amplifying the effects of low airplane cabin humidity.