Fog inside the plane? Understand why you don’t need to worry

It’s a phenomenon you may be familiar with if you’ve ever boarded a plane on a humid day. Hot, stuffy air from outside meets cold air from inside coming out of the aircraft’s air conditioning unit—temporarily creating what feels like mist or mist inside the cabin.

A few weeks ago, the user of TikTok Savannah Gowarty posted a video of fog and condensation on a US domestic flight. The video received more than 13.1 million views, with comments surprised and confused questioning what was happening.

Short answer: It’s a natural occurrence that usually lasts a short time and is nothing to worry about.

“On hot, relatively humid days, cool air from the aircraft’s air conditioning system mixes with the warmer, more humid air in the cabin and reduces it to the dew point, creating fog,” said a spokesperson for the Federal Aviation Administration. Aviation (FAA) to CNN Travel .

“Fog is usually short-lived as the cooled air quickly warms above the dew point.”

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Scientific explanation

When a plane is waiting on the ground before departure, the air in the aircraft’s cabin is kept cool “either by an external air conditioning unit on the ground or by the aircraft’s own Auxiliary Power Unit (APU), as the spokesperson explains. of the FAA.

“Both provide cool air (generally much colder than ambient temperature), which can temporarily lower the dew point of aircraft cabin air enough to create fog.”

Climate scientist Indrani Roy, who works at University College London, says the environment on board a plane also creates perfect conditions for condensation in the cabin. That’s why cabin surfaces — and people — can feel damp. Condensation occurs when water vapor in the air — which is “prone to sticking,” as Roy says — comes into contact with any colder solid surface, and there are many solid surfaces inside an aircraft.

“Condensation is therefore more likely in the cold solid surface areas of the cabin,” says Roy, who further points out that neither the fog nor any resulting condensation is “cause for alarm.”

But while humidity-fueled fog is perfectly safe, passengers can sometimes be “worried,” especially when they experience it for the first time, says flight attendant Rich Henderson from the US.

Usually it’s because they mistake the fog for smoke, Henderson tells CNN Travel . “But a quick explanation usually helps ease any nervousness they might have,” says Henderson, adding that, in general, passengers “don’t tend to be too alarmed.”

“Most of the time, they are confused about what it is. But when you explain to them that it’s just condensation of cold air from the aircraft’s air conditioning system meeting the warm, humid cabin air, they understand very quickly.”

Passengers often see the funny side, too, adds Henderson. “I often make a joke that it’s like we’re in a 1980s music video and that usually makes people laugh really quickly.”

Disappeared in seconds

For flight attendants, judging whether passengers prefer a slightly longer scientific explanation or a shorter, more humorous take is part of their skill set that they hone on the job. Henderson says these interpersonal skills aren’t something that’s particularly taught in training, but it’s something you learn quickly when you’re interacting with different people, with different perspectives, on a daily basis.

Anything that is “unfamiliar to passengers can cause some anxiety from time to time,” says Henderson — pointing to unexplained noises or engine sounds as another culprit. “A simple explanation and a little joke usually does the trick.”

So there you have it — airplane fog is nothing to worry about, and just a chance for you to embrace your inner 1980s pop star. And while you may be worried about the fog ruining your look, “aircraft cabin fog generally dissipates very quickly,” explains the FAA spokesperson.

“This occurs because the cooler air (which has reduced the cabin air temperature to its dew point) quickly heats back above the dew point. When this happens, the fog will disappear. Often the mist only appears when it comes out of the vent, exists for 1-2 seconds and then disappears.”