Unfortunate side effect of summer travel could get you pulled aside at airport security

It's been a sizzling summer so far in the United States and Europe, but there's one lesser-known side effect of all these high temperatures.

Heavy perspiration can earn you a pat-down at airport security, particularly if it's pooling in intimate pouches.

Ever had the machine go off and the security officer had to wave over you with the magic wand? Moistness might well have been the problem.

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CNN asked the TSA to explain why this happens.

"Added moisture from a person's body can alter the density of clothing, so it is possible perspiration may cause our Advanced Imaging Technology machines to alarm," a spokesperson said.

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"If this occurs, the passenger may need to undergo additional screening, such as a pat-down in the area of the body where the AIT alarmed, to ensure there is no threat."

It comes after another airport security worker has revealed some of the "red flags" they look out for in passengers earlier this year.

Jeff Price, an airport security coordinator-trainer with 33 years of experience in aviation security, said there are a "variety" of things that people are trained to look for and it's never about just one behaviour, but rather "clusters" of suspicious actions.

"One of the things we do [to] train is we'll send people out to watch [airline travellers] and just observe their behaviour and get a baseline of what's normal in the airport," he told Fox News Digital at the time.

One of the more common behaviours that may be a red flag among security is whether people are dressed appropriately for the weather at their departure or arrival point.

Also, yawning too much.

"Exaggerated yawning, lots of yawning – that might attract attention," said Jeff. "When people are stressed, they tend to want more oxygen."

Sweatiness or otherwise, TSA lines will move a little faster from now on, since last week TSA removed the requirement for all passengers to take off shoes at airport security checkpoints.

Shoes can now stay on, as long as the passenger has a REAL ID. This is a federally accepted form of identification, like a US state-issued driver's licence or ID card, or a passport.

The security check on shoes was first implemented after Richard Reid, aka the "Shoe Bomber", hid homemade bombs in his footwear in 2001.

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