Geiger Counter on an Airplane

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Geiger Counter on an Airplane

Last week I took a flight out west and back again. I wanted to take my Geiger Counter but I was worried that they might be banned. Calling the manufacture, two distributors, and a very knowledgeable person I know all, all suggested that Geiger Counters were fine to take on an airplane. I continued to worry, being me, so I checked the TSA’s website. The Website allows you to enter items to search their “banned” list. Geiger Counters, radiation detectors, and nothing of the sort would come up. I searched equivalent devices, i.e. small electronics with simple circuit boards and batteries, only to find all were acceptable to take and even use. Lastly, I contacted the TSA directly using their phone number. I spoke with an agent at length who ensured me that it would be okay if I clearly displayed the device as I was searched. It was worth the risk in the name of science!

Before anyone questions, I should explain that I took the Geiger Counter out of my carry-on and placed it in a separate plastic examination bucket by it’s self. The TSA guards glanced at it and ran it through the X-Ray machine. I only regret not having it on to see what they subjected it to. I figured that was too far. Afterward I have a polite discussion with a TSA screen-er and a passenger who complained, half humorously, about the radiation.

Unruly Passenger

While preparing for my return flight, I had already logged the data, I encountered an immediate use for my new knowledge: A gentleman was just behind me as I reapplied by belt and shoes. He complained out loud about the radiation of the body scanners. The TSA guy was about to say something in rebuttal, but I took a moment, Geiger counter in hand, to step forward and interject my two cents:

“Sir, that back scatter machine is sort of like being electronically raped, but it really only blasts you with a tiny bit of radiation for a few moments. The flight your about to get on will expose you to about a third of a milirem per hour, give or take. A four hour flight and you get 1.2 milirem of radiation. Sir, that means every 33 hours of flight you get a full power chest X-Ray. Doesn’t the doctor hide in a different room and wear a lead smock for that?”. Due to comments, I should note that the body scanner is over a thousand times less (or more) than the flight.

The TSA guy tried with careful determination not to reveal his laughter. The passenger just gave me a strange look, snatched his belt, and walked off. I looked at the TSA agent and shrugged. We were unlikely cohorts in this joke. I personally feel that fully body scanners should tip you a dollar after you’re done giving them a show. I am also annoyed by being subjected to additional radiation, but it seems to go with the flight. Perhaps one day we can abolish fully body scanners in lieu of some better approach.

The Data

I took my Geiger Counter on a Airplane last week and up to an altitude of 36,000 feet. At about 36,000 feet I stuck my hand in my bag and engaged the Geiger Counter without sound. Though they are allowed, I figured a blinking light, digital readout, and ticking noise were inadvisable show general show. I attached the data cable and plugged it into my laptop. Below are the full 17 minutes of readings I took before too many people started watching my screen. Next time, I hope to leave my laptop running with the lid down for a few hours.

17 Minutes at 36,000 feet over the Midwest USA at about early afternoon.

Radiation at 36,000 Feet

Radiation at 36,000 Feet

Minute Date Time Count Total Counts Average Count
1 5/16/11 02:46 PM 317 317 317
2 5/16/11 02:47 PM 338 655 327
3 5/16/11 02:48 PM 300 955 318
4 5/16/11 02:49 PM 318 1,273 318
5 5/16/11 02:50 PM 296 1,569 313
6 5/16/11 02:51 PM 364 1,933 322
7 5/16/11 02:52 PM 305 2,238 319
8 5/16/11 02:53 PM 315 2,553 319
9 5/16/11 02:54 PM 325 2,878 319
10 5/16/11 02:55 PM 303 3,181 318
11 5/16/11 02:56 PM 302 3,483 316
12 5/16/11 02:57 PM 350 3,833 319
13 5/16/11 02:58 PM 346 4,179 321
14 5/16/11 02:59 PM 352 4,531 323
15 5/16/11 03:00 PM 314 4,845 323
16 5/16/11 03:01 PM 366 5,211 325
17 5/16/11 03:02 PM 314 5,525 325


In Conclusion

Flying remains quite safe. I am exposed to more danger from driving to the airport than the plane. The radiation I am exposed to is quite low given short duration of the flight.


  1. Max says:

    I can’t help but feel your rebuttal to the passenger is rather poor. You suggest that the passenger shouldn’t care about the radiation he is exposed to because he willingly exposes himself to equal amounts of radiation on a long flight — akin to that of an X-ray that a doctor shields up for.

    Are you suggesting that the passenger should accept doubling the dose of radiation that would lead a professional to run out of the room? Makes no sense to me.

    • tom says:

      Thanks for the comment. The environment and surroundings, the context, are important when considering a comment and the impact. The gentleman in question had already been quite rude to start with. While I disagree with full body scanners for many reasons, the dose from a 4 hour flight is perhaps several thousand times higher than the scanner. I find it odd that people fear one and not the other. I dislike the scanners for privacy invasion and the electron dislodging affects they induce, possibly, though not proven, causing more damage than normal radiation of the same dose. In short, they (scanners) probably need a greater equivalent dose weight than a normal x-ray.


  2. Luis says:

    Actually a flight of ten hours shoud expose you to about
    10-20 Mrem of radiation
    Pregnant women should be banned from taking long flights
    Did you check the multiplier factor in your dosimeter?
    If it was a portable one it overlooked the gammas and the

    • tom says:

      You are correct about my math. I experianced math fail, for sure! It was in correct for me to use sieverts as a unit given my lack of knowing the energy involved. But, if I had received about 350 CPM for ten hours from Cs137, gamma only, i.e. the exact source my GM was calibrated for, I would have received: 350 x 60 = 21,000 counts per hours. 21000 x ten hours = 210,000 Counts. 210000 / 1000 = 210 uSv total. Further, 210 uSv/10 = 21 mR total (for Cs137 gamma only).

      So, given the energy differences and weighting factors, the measure of 20-40 mrem is probably correct.

      I admit a total math fail. =)

      Also, my unit, the CRM-100, has a thin window alpha detector and a full Geiger tube. I brought a real geiger counter, not a dosimeter. Thanks for the catch!!!

      I’ll correct it later today.


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