That first sip of a drink while flying a couple miles above the Earth’s surface is intoxicating. By the time you finish the beverage (which should, by the way, be a Bloody Mary), you feel a heavy buzz—much more than you feel when you drink the same amount at sea level. But do you actually get more drunk on an airplane and at high altitudes? No, but you might feel like you are.
“Your blood isn’t oxygenated as much at altitude as it is on the ground,” Dr. David Greuner, a cardiovascular and thoracic surgeon, told Thrillist. “So, there’s just not as much oxygen going to the brain, and you get hypoxic. It’s the same reason you might feel light-headed at high altitudes or when you exercise too hard. You’re light-headed, and you might think it means you’re more drunk.”
Commercial planes typically fly between 30,000 and 40,000 feet. The cabin is pressurized to the equivalent of the air at around 6,000 to 8,000 feet to make it manageable, according to the World Health Organization. That’s still high enough for some people to feel an impact, though. Higher altitude means lower air pressure, and the lower the air pressure, the less oxygen a person’s blood is able to take in. When there’s an oxygen deficiency in the body, it’s called hypoxia. According to Higher Peak, an altitude training device company, the effective oxygen percent decreases dramatically from sea level to flying level. Effective oxygen is 20.9 percent at 0 feet, 16.6 percent at 6,000 feet and 15.4 percent at 8,000 feet.
For perspective, compare airplane cabin air to the dry air of Denver, Colorado. The Mile High City sits at around 5,280 feet (around 17.3 percent effective oxygen level). Dr. Ben Honigman, a professor at the University of Colorado School of Medicine, told the Denver Post that between 8 and 10 percent of people who travel to Denver will feel the effects of Denver’s altitude. It’s common enough that the Denver tourism department gives this piece of advice:
“In Denver’s rarified air, golf balls go 10 percent farther...and so do cocktails. Alcoholic drinks pack more of a wallop than at sea level. It is recommended that you go easy on the alcohol in the mountains and in Denver, as its effects will feel stronger here.”
Now add up to 3,000 more feet to that and you have the altitude level that airplane cabins are at. The effective oxygen level is up to 2 percent less in a plane than in Denver, making the effects that much more noticeable.
But the key word in the city of Denver’s statement is “feel.” You won’t actually be more drunk, you’ll just feel like you are because of the light headedness that comes with breathing high altitude air with lower oxygen levels. The science behind high altitude drinking is clear: You won’t get more drunk unless you’re very, very high up.
The Federal Aviation Administration (FAA), did a study in the 1970s that measured the cognitive ability of people at 12,500 feet—more than 30 percent higher than the effective air pressure in a plane cabin. The FAA found that alcohol impaired people equally at 0 feet and 12,500 feet. Like all good studies, it was repeated and the same results were found.
So don’t let the airplane drink get to your head. You might feel like you’re more drunk after a drink in the air, but blood alcohol level wise, you’re not.