Having travelled through SFO a few times, and each time been asked to go through a millimetre wave (or backscatter) scanner, and each time 'opted out' and gone for the search (in public), I'd like to know what is the proper reasons to give when they ask why I've opted out.

I tried the radiation argument the first time, just after they were introduced, but this argument doesn't seem to be too valid now since the millimetre wave scanners aren't very powerful.

I've tried privacy but not really known what to say afterwards other than the technical issues of caching, wiping images, etc.

Each one got some snarky comments from the security staff, and discussion from the one given the opportunity to feel me up, so I'd like to arm myself with a bit more information/argumentation for next time.

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    What do you mean by "correct"? What IS your reason?
    – nibot
    Commented Mar 13, 2012 at 7:48
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    My reasons are both of the ones I mentioned. I travel quite a lot, so any way to decrease exposure to anything I see as a benefit, as well as having issues with the 'security theatre' of airport security trying to make us feel safer while trying to get us to increase the level of acceptance of privacy invasion. I'd just like to have some proper argumentation, both for their statistics (since they make a note of each instance of opting out, with a reason), and so that I don't sound like someone that hasn't done any research.
    – dsample
    Commented Mar 13, 2012 at 10:44
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    "I like to be fondled by men and women who can't get what they want elsewhere" counts as an argument to you or not? >;-) I've certainly seen it mentioned as a direct result of refusing to submit...
    – jwenting
    Commented Mar 14, 2012 at 6:32
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    The radiation argument is very flimsy as the amount of solar radiation you receive by flying in thinner atmosphere 35000+ Feet up is higher that what you receive in the ground in a scanner.
    – user987
    Commented Jul 26, 2012 at 10:16
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    This is my answer "Your past assurances that the back-scatters were safe proved to be wrong didn't they...so until you (the TSA) provide independent 3rd party confirmation that this technology is indeed safe, I'm opting out."
    – user3052
    Commented Aug 25, 2012 at 23:03

6 Answers 6


Why do you need to give them an excuse? [Currently] we have the right to opt-out, no questions asked. Having to explain yourself eats away at this right.

I've never been asked why I opted-out, but if I was, I think I would say something like "to protest overly-burdensome security regulations". Which is the truth.

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    You make a very good point. Every time I've opted out so far they've put me in a little pen and then 2 security people have approached me, one with a folder and pen and just making a note of the date, time and the reason. I've not considered the 'right' to opt-out without a reason, and being approached by security staff can be pretty intimidating, even for someone that doesn't get intimidated very easily, so usually I feel like I should give an answer... snarky comments from them about your reason just don't make you feel great.
    – dsample
    Commented Mar 13, 2012 at 10:50

I tried the radiation argument the first time, just after they were introduced, but this argument doesn't seem to be too valid now since the millimetre wave scanners aren't very powerful.

Who told you this? The guys at the gate who don't want to pat you down? Tell them you only take medical advice from certified doctors and PhD's.

  • Not only their comments, but also some basic info/comments I've seen online. As @Loren mentioned, I've heard the backscatter scanners still have medical issues around them still, but not so much the millimetre wave ones. If there is some real reason to be concerned still about the millimetre wave scanners I'd be happy to see some research/evidence to back it up.
    – dsample
    Commented Mar 12, 2012 at 21:47
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    Although I've never been asked, this has been my reason for opting out in the past. The problem is, they always make me wait right next to the freaking x-ray machine while they go get somebody to pat me down!
    – user82
    Commented Apr 19, 2012 at 14:51

You don't need to give any excuse at all. They can't force you undergo this procedure, you volunteer to it. If you don't want to - then you don't. They'll have to use the good old manual search on you.

That said - why do you care? Do you believe that it will cause you any damage? I'm pretty sure we're all exposed to much higher levels of radiation from our cell phones, microwave ovens DECT phones and WiFi routers, so once in several months that you need to go through this scanner (and its not always used in SFO) won't add much to that.

If its privacy concerns... Well, feel better when someone standing right in front of you touches your groin? I don't.

What is it?

The only reasonable (to me) explanation would be ideological: you don't want it because you believe they shouldn't do it altogether. Well - you can just say so, its your right.

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    I travel pretty frequently, so it's more than once every free months, unfortunately. The comment about the radiation is pretty much the same comment the security staff made when I mentioned that as a reason the first time, so as I said, that's probably not as valid anymore. About the privacy though, I don't totally agree with the full body pat-down, but I'd rather have a human being doing this in person than someone in a remote location doing it, then there's an aspect of causing the security staff to be a little uncomfortable, plus they don't get a photo.
    – dsample
    Commented Mar 13, 2012 at 10:58
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    So what's the problem stating all that? Why do you need to invent a reason when you have a perfectly valid real one? Whatever reason you state other than ideology will make you look ridiculous (at least IMHO), so why does it matter what exactly makes you look ridiculous? If you insist on giving a reason at all, for god knows why...
    – littleadv
    Commented Mar 13, 2012 at 17:19
  • Just to mention that the sources of microwave radiation listed above are non-ionising radiation. It's ionizing radiation (and UV, which is a bit different) which can cause problems like DNA damage and increased cancer risk - and that's the type that is in x-rays etc (but don't forget it's all about the size of the dose - all sorts of things, including sleeping people and bananas, give off ionizing radiation in harmless tiny doses. Commented Aug 25, 2013 at 19:23

Well, you can still try the privacy argument, among others. Here's a summarised version of what Wikipedia has to say:

Privacy advocates are concerned about the use of active millimeter wave technology because it effectively implements routine and, in many cases, mandatory virtual strip searches. It allows screeners to see the surface of the skin under clothing, prosthetics including breast prostheses, and other medical equipment normally hidden, such as colostomy bags.

Tumors - While the majority of animal cancer studies show no response to chronic exposure of microwave radiation, some show an increased rate of tumor growth. The same increase also occurs in chronically–stressed animals not exposed to radiation.

I've also seen some people claim that they get claustrophobic being in the machine, but that's a tough argument to 'prove'.


Not only is the "radiation" issue invalid, but the privacy issue is also a non-issue. After the public's dislike of the remote viewing of images, the scanners were changed so that instead of producing an image that someone looks at and then radios the screening person where to check the passenger, it now automatically finds objects itself and uses a generic, cartoon-like avatar of a person as a map, and displays a yellow box on the area of the passenger that the screening person should check. This eliminates the need for any image. It is also good for the screeners, since it lessens the manpower needed to run the operation. The only (small) downside is that since the computer can't think like a human, you will get more false positives that would otherwise be dismissed by a thinking person looking at an image and recognizing a harmless object like a nickel or something.

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    Hi and welcome. Do you have any references for these claims?
    – JoErNanO
    Commented Dec 28, 2014 at 14:55

My reasoning, which no one has questioned, is that I believe such scanners are security theatre, that they are unlikely to turn up anything that a trained agent would not already note, and that putting money into them means less funding for the actual people who make it work. Therefore, I refuse those scans because it's supporting the false idea of their effectiveness. This is a sincere belief on my part and I like to think that the workers appreciate that I think they're more important than the multi-million dollar equipment.

That said, I think I've been asked once why I was refusing the millimeter wave scan. For the most part, they really don't care.

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