Home Travel Why The TSA Swabs Your Hands, Phone, Laptop, Food, Bag, Shoes, etc.

Why The TSA Swabs Your Hands, Phone, Laptop, Food, Bag, Shoes, etc.

by SharonKurheg

It doesn’t matter if you’ve just spent 30 minutes in the regular TSA queues, less than 5 minutes in the TSA Pre-Check line or 1 minute in the CLEAR area, all lines eventually lead to, not Rome, but the security scanners.

Once you’re there, it doesn’t matter if you’ve done this a bajillion times before, or even if you haven’t and know what to do to get you through the scanners quickly, you might go through the machine and get the random beeping alarm. Or maybe you got the dreaded SSSS on your boarding pass.

Either way, the TSA workers pull you aside and say you have to go through a secondary screening. It usually just involves them swabbing your hands (and/or your cell phone, laptop, food, bag, shoes, etc.), putting the swab in an Explosives Trace Detector (ETD) and, when given the all-clear, you’re told you can be on your merry way.

But why are they doing that? And why YOU?

The “why you” is pretty simple – it’s usually at random. Unless you’re on the super-secret list that increases your chances of getting SSSS on your boarding pass, the TSA’s machines are said to pick people at random for swabbing.

As for the why, they’re usually checking for traces of explosives. These could include:

  • NG (nitroglycerin)
  • ANFO (ammonium nitrate/fuel oil)
  • PETN (pentaerythritol tetranitrate)
  • RDX (nitramide)
  • TNT (trinitrotoluene)
  • Tetryl (trinitrophenylmethylnitramine)
  • Semtex (plastic explosives)
  • Nitrates
  • HMX (octogen)
  • GSR (gunshot residue)

(Heads up that there’s no specific list of what the TSA is looking for – that information is “Sensitive Security Information (SSI),” but the above are some of the items that potentially make things go “BOOM,” so…)

Anyway, if they decide to swab your phone, laptop, food, bag or shoes, there isn’t much you can do – hopefully, you wouldn’t have anything on those that would cause a problem when their swab goes through the ETD (or if you think they might, wipe them down beforehand). However, your hands have a higher chance of an issue, since they can potentially handle things that have, for example, glycerine or nitrates, since there are lots of typical, everyday items that have those chemicals in them. So just in case, here’s how to help avoid getting a false positive on a hand swab test.

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This post first appeared on Your Mileage May Vary


mike murphy August 26, 2019 - 1:26 pm

they have to justify their jobs ?

mike murphy November 17, 2020 - 10:54 am

to see if you look nervous ?

Bill Slotsve May 3, 2021 - 6:14 am

I was taken into secondary inspection where they swabbed my hands. I saw that I was the only racial minority boarding at FCA that morning. I had no idea what they was swabbing for so I told the guy I was at my shooting range hours beforehand. I was allowed to board however.

Boraxo June 25, 2022 - 6:35 pm

The whole process is idiotic and fraught with peril. We were delayed an hour at LAX after my wife tested “positive” when connecting from Mexico. We
were told that we had to wait because there was only one TSA explosives expert in the entire SoCal region could clear the false positive. A complete
Load of BS

SharonKurheg June 25, 2022 - 6:44 pm

I’m sure you arrived at the airport in plenty of time to allow for a situation like that to happen, as is always recommended. So the extra hour shouldn’t have been a problem.


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