scanners coming to Australia

Sorry if I incorrectly paraphrased you on this, that was the point I was fumbling around trying to make. I don't know enough about MMW to make a case on the safety issue and many knowledgeable folks like you don't seem worried about the health implications.

Conversely, there is a whole contingent of radiologists and scientists, including one from Johns Hopkins saying that the x-ray units pose some health risk. So, it is known that the underlying technology (x-ray) is potentially hazardous, it is simply a question of dosage.

I think the MMW safety argument is probably the weakest of all of the points against TSA procedures, particularly while there are still x-ray scanners and strip searches going on. My point was that being too aggressive on this issue in the absence of evidence diverts attention away from the bigger problems and unfounded claims compromise credible arguments on those other issues.

BTW, are the MMW electromagnetic or radio (sonic) waves? These articles usually say they use electromagnetic.

 

Fisher, cool on the rest of your points.

MMW is electromagnetic which is radio waves. That is, the same "stuff" as cell phone transmissions, radio and television broadcasting, satellite communications, air traffic communications, ship-to-shore radio, ham radio, WiFi, radar, Bluetooth, communication with spacecraft, CB radio, your garage door opener, walkie-talkies (have I missed anybody? ) and (at higher frequencies) infrared, light, ultraviolet, and (at much much higher frequencies) x-rays and gamma rays. Electromagnetic waves are electric fields and magnetic fields varying in such a way that they propagate. EM waves can travel in a vacuum. Sonic (sound) waves are variations in the density of air molecules (or water, or whatever the medium is). For that reason, they cannot travel in a vacuum. ("In space, no one can hear you scream.")

 

RadioGirl, I'm following your comments very closely and have the greatest respect for your opinions, particularly in light of your very clear opinions of the X-Ray scanners, the invasive custodial-type searches misleadingly called "pat-downs," and the general hoop-la of the TSA. I'm only sorry as to what you'll apparently be facing soon in Oz.

I'm sure you realize yourself that, by changing a few words in your post #20 above, it would look very much like those reasonable arguments that other experts make in favor of the X-Ray scanners. The TSA ringmaster during our thoroughly unpleasant experience at a SEA checkpoint last month threw the "cell phone" argument around quite freely. It was when I questioned his expertise that things turned really nasty (I have no fear of that with you ).

As a geezer, I do still wonder about the effects of those unleashed radio waves bouncing around in a way that they didn't in the past. When microwaves were introduced there were a lot of questions about the safety. The same goes for the radar guns used by police. We do still read such warnings as:

Even in such industry-friendly Q&As such as the above, there seem to be a few little caveats. Why should the police officer point the radar gun away from himself/herself? Why are there any standards for microwaves if they're so safe?

I might continue to opt out of the MMW in the US "because I can," as I said to perfectly courteous employees at DRO a week ago, but I still stand ready to be reassured.

 

Thanks. I should have known that.

I often use ultrasonic test systems to assess steel tanks and the like which doesn't produce an image per se but provides localized wall thickness and leak information. I'm somewhat familiar with ultrasound "photos" of babies taken during pregnancy which are pretty grainy but informational to the OB.

So the articles are correct when comparing MMW to cell phones on the basis of the technology.

So perhaps the best argument on these is the high number of false positives and the additional time required to go through them. The MMW takes 10-12 seconds and the WTMD only 1-2.

 

Me too. And I will opt out or avoid them if I can, on principle, but I am not worried about any health risks.

Fair enough, and the key difference is that I have advanced degrees in radiocommunications, have backed up my claims with links to the FCC (see the other place) and other authorities, and am still here to try to continue to explain in terms that people can understand. I believe that the TSA screeners are either ignorant in confusing the x-ray scanners with the "cell phone" argument re MMW, or they've been told to use the cell phone argument for both kinds of scanners. At the end of the day, I know it's completely your choice as to whether you want to believe me or not. I'm just trying to keep people who are opposed to the NoS, as I am, from undermining their numerous valid argument by making unreasonable claims about safety concerns of MMW.

Except that it's not all that recent. The sun naturally emits radio frequency energy across the spectrum. Radio broadcasting has been around since about the 1920s, television since the 1940s, walkie-talkies and CB radio for decades, and so on. People used ship-to-shore radios and CB and ham without ONCE worrying that it might be dangerous. It just wasn't obvious to most people that this was all around them until the worries about microwave ovens and later, cell phones. The energy you are exposed to from those things, every day for many years, is much more than the energy of the MMW.

See my reply to Phoebe above. At microwave frequencies (as used in microwave ovens (2.4 GHz), police radar (10 GHz) and the MMW scanner (30 GHz), there is a possibility of damage to people when the power is high enough to heat skin, muscle, etc. (One of the most sensitive organs is the eye, and high levels can cause cataracts.) Safety standards are set by evaluating the level that would cause this heating, and then setting the standard much lower than that, just to be conservative. (That is, the standard might be 1/100 the level that would cause heating.) The radio energy hitting a body is dependent on the (a) power of the transmitter, (b) the antenna pattern - does it direct all the energy in one direction or spread it everywhere?, (c) the distance between the antenna and the body, and (d) if there's any screening or blockage of the radio energy between antenna and the body. Power decreases in proportion to the square of the distance. So if you are standing 10 feet from the antenna and I'm standing 20 feet away, I'm getting 1/4 ( = (10/20)*(10/20)) the energy you are. Someone standing 100 feet away is getting 1/100 the energy you are at 10 feet. And if a directional antenna is pointed towards me and not at you, at the same distance, I'm getting more exposure than you. So the points you quoted above are criteria to ensure that the user is not receiving exposure levels that exceed the safety standards that would produce heating. Radar transmitters are, compared to most communication transmitters, rather high powered, and the police officer holding the radar is, by definition, really close to it, so if he points the antenna at himself, the exposure level due to the combination of power + short distance + antenna pattern is higher than allowable. A microwave oven is also higher powered (900 Watts) than communications systems (WiFi = 1/4 Watts) but the screening of the oven keeps 99.99999% of the energy inside where it can cook the food, and reduces the amount that leaks out to below the safety standard.

I'll draw an analogy to sound. Listening to soft music for days at a time is harmless. The police radar is analogous to an airhorn - it's high powered and hand held. If you have to use one, you wouldn't want to point it directly at your own ear, which would certainly cause damage, but it's okay if you could point it away from yourself. The fact that blowing an airhorn into your own ear is dangerous doesn't make sound, in all its forms and varieties, dangerous in itself. Similarly, if you had a noisy piece of machinery, you might put it in a box with sound baffles to bring the noise down below a dangerous level. That's sort of what the microwave oven shielding does.

And I completely support your right to opt out "because you can" and if I can do the same in Australia, I certainly will.

 

Many thanks for addressing my questions and concerns so thoughtfully and logically. Your analogy to sound is particularly useful to this former high school band teacher.

 

When I consider the (possible) introduction of MMW/ATR at Australian international airports, those would be two of my strongest arguments. There is no health issue and the ATR without a backroom viewer reduces a lot of the privacy concern. Australia doesn't have the equivalent of a 4th amendment for me to invoke. In addition to the false positives (with associated post-scan patdowns) and the slowness, I am pointing out to people the privacy problems for women with sanitary items or people with medical devices like insulin pumps. And the risk of someone walking off with my laptop or handbag while I'm standing in the machine.

Also the ineffectiveness - not only does the scanner alarm on things that aren't there, it doesn't find things that are there, as shown by the German video and the DFW(?) test where a handgun was not found 5 times out of 5. Also the outrageous cost for very little benefit. And so on. Lots of reasons to oppose these things.

 

With all due respect, RadioGirl, we don't care how we look to your "professional colleagues". We understand that radio waves are your friends, and you like them. However, you're not the only engineer here.

What you read between the lines, and what the industry chooses to disclose don't really matter. We're dealing with a government agency and an industry that has a track record of not having its products independently tested and of repeatedly lying (e.g. the Johns Hopkins "certification") about the nature of the testing that has been done. Most recently TSA agreed to have its nude-o-scopes properly and independently tested and are now trying to renege on it. That suggests to me that these products (quitely possibly including MMW) are potentially a lot more hazardous than they would have us believe.

When they are forthcoming with proper independent evaluation and testing and disclosure of the radiation effects and of the machines' maintenance cycles and failure rates and effects when they fail, then and only then can the public make an informed decision. A proper engineering evaluation of the units would include not only measurement of the normal radiation levels present but also of the safety feature in the electronic circuitry: What are the potential effects when these components fail, and how often do these components fail? Are there any standards for acceptable exposure levels by humans of radiation at this wavelength? If not, that's a really big negative; that needs to be established scientifically before any claims of safety can be made. Is the manufacturer an ISO 9001 company? Are they in compliance with all the corrective measurements in their quality audits? Etc.

Lots of legitimate questions, and I suspect that in their haste to roll out these units, TSA & L3 have properly addressed very few of them.

 

Lacking proper standards and evaluation of the product & of the company's quality procedures & of maintenance & usage in the field, this statement is 100% (expletive deleted).

 

It's not convincing to another engineer. My degree might be in classical languages, but I've worked with electronics (including radar) for 15+ years. There's a lot more involved in safety than just thinking you know what the power level is and thinking that said power level is safe.

We can only reach that conclusion when proper standards are in place and TSA & L3 are forthcoming with independent evaluations and adherence to those standards. Quips like "less radiation than two minutes in flight" and "1/10000 a cell phone" are meaningless.

 

It's also the first usage of the technology in which the energy is focused on the human body on a mass scale. You're making a big leap here which should only be done with proper standards and evaluation in place.

Only if it sprouts a directional antenna and focuses its energy on me. The Nude-O-Scope is already focused on me.

 

That's okay, but if they won't take your other arguments seriously because of this, it's not very helpful.

Or it might be that the x-ray is more hazardous that they would have us believe, and the MMW is well within established safety standards.

Re failure, I can only say that the same applies to WiFi and cell phones and CB radios. When radio electronics fail, they may shift in frequency by some small amount (not from microwave to x-ray) or they just stop working. They don't suddenly start transmitting 100,000 times too much power.

And of course there are standards for acceptable exposure levels of humans at this wavelength (frequency of 25 - 30 GHz). This report by the FCC Office of Engineering and Technology (1999 - predates the NoS) says:

Table 1 (won't try to copy it here but it's in the link above) says that the General Population exposure limit for 1.5 - 100 GHz (which covers the MMW scanner range) is 1 mW/cm2, averaged over 30 minutes. (Occupational exposure is 5 mW/cm2, averaged over six minutes) mW is milliwatts.

Documents filed in 2004 with the FCC - pdf letter here - to convince the FCC that the MMW scanner would not interfere with other radiocommunication systems in the same band address the issue of human exposure. They note that even with a person leaning into the direction of the antenna, the exposure level would be (instantaneously) 13 microwatts/cm2, which is 0.013 mW/cm2, well below the General Population limit of 1 mW/cm2, and that when a short exposure is averaged over 30 minutes (as specified in the standard), it is 13 nanowatts/cm2 or 0.000013 mW/cm2.

Put another way. Other documents filed with the FCC - pdf letter here - to convince the FCC that the MMW scanner would not interfere with other radio systems say that the under the waiver they are applying for, peak emissions will not exceed 0 dBm at a distance of 4.5 m from the antenna. 0 dBm is 1 milliwatt, or 1/1000 of a Watt. A cell phone is ~2 Watts. So the transmitted power is 1/2000 of a cell phone. But the power decreases as the square of distance and you’re probably at least 10 times the distance from the NoS antenna as you are from the cell phone. So that’s another factor of 100. So the power hitting you from the NoS is ~1/200,000 of the cell phone. (Advanced students will know that path loss at 24.5 GHz is higher than at 900 MHz, giving an even greater margin.) Even allowing for some slop in these back-of-the-envelope calculations, the figure of 1/100,000 of a cell phone is in the right neighborhood.

If, as an engineer, you want to challenge these figures, please go ahead. But to just say that because you haven't personally seen the testing results that there are no testing results and that therefore there's a big conspiracy to cover things up is not

Well, except that it seems the MMW people DID address these in their filings with the FCC. And if these figures are off by factors of 100,000 or more (which they would need to be to start to exceed the exposure standards, I'm pretty sure the FCC could see through it. Not to mention the companies running radio systems in this band, who are desperately worried about interference and have been trying to find holes in SafeView's arguments.

 

But it's not "thinking I know" what the level is and "thinking I know that the level is safe." Standards ARE in place.

"Less radiation than two minutes in flight" is a faulty analogy since the energy levels of backscatter x-rays and cosmic radiation in flight are different. That doesn't mean that "1/100,000 of a cell phone" is also meaningless; the frequency is in the same ballpark and the power levels can be directly compared, as I've shown above.

 

Using a directional antenna simply means that more of the energy goes in one direction and less of it goes in the other directions. But that only matters in combination with the transmitted power. If the transmitted power is 0.001W, and the antenna points it all in your direction, there's 0.001W coming your way. If the transmitter power is 100 W but the antenna transmits equally in all directions, maybe 1% will hit you, so there's 1W coming at you. The fact that the first case is directional is irrelevant; you're still getting more exposure from the second case.

All of the calculations above include the effect of antenna gain, so the fact that it's focussed is already accounted for.

It's worth noting, if you read around on the FCC website I linked, that there was (a) significant concern from companies who were developing in-building directional radio links at exactly the same frequency as the MMW scanner and almost certainly at higher power levels. While you might not be standing in the main beam of those systems, the power in the sidelobes of the antenna may well be higher than the MMW scanner exposure, and it's continuous. And (b) despite these worries, the FCC has received no reports of actual interference occurring.

At the end of the day, you're claiming that I "love radio waves" and so I'm biased. We need to make sure that our (justified) mistrust of the TSA and our (justified) opposition to these scanners on a number of other grounds does not make us biased in the other direction. My only reason for pursuing this (and this is my last message on the subject) is that claims that the TSA are covering up the hidden dangers of the MMW really do detract from the credibility of our other arguments.

 

What we need are for TSA & L3 to say "these are the standards (health standards as well as FCC standards) that have been met, and this is how compliance with those standards has been met. Until they're forthcoming with that, they're just whizzing in the wind.

Two problems with this: One is that it's not a matter specifically of "hidden dangers" but a lack of open standards, compliance and certification.

The second is the philosophical "argument against the man": When someone (or an organization in this case -- TSA) is consistently deceitful and untrustworthy, you are justified in treating any information from that source as deceitful and untrustworthy.

After a rush of really bad PR last July-August, TSA tried to manage the media by coordinated a PR blitz around the country every time they rolled out MMW at a new airport. The public bought into that for while, but it's no longer working. We need to keep the pressure on the on all fronts, and my bet is that most of us will do exactly that.

I'm perfectly willing to concede that MMW is "probably safe", but that simply is not good enough for a product that will be used to irradiate tens of millions of people multiple time annually. They MUST do better: Standards, compliance, certfication. Until we have that, it's a no-brainer to me.

 

Great points!

So that makes four issues that avoid the health risks on the MMW so that those complaints can can be focused on the BKSX scanners, which I think have a good chance of eventually being replaced with MMW.

While the ATR may address the overall privacy issue for most folks it applies an excessively heavy burden on the groups you mention.
Ironically, while TSA says these help those with medical issues such as artificial hips and knees, it actually makes it worse for those with ostomy appliances, insulin pumps and younger women.

I'll still refuse these just on principle and the fact that it further funds the security industry that I oppose in general.

(Added) I also agree that TSA needs to come clean and allow open testing to verify their safety. Their track record of lying is a big issue. As the saying goes, "they'd sooner climb a tree and lie than sit on the ground and tell the truth".

 

So if there are no opt-outs allowed, what happens if I pinch a nerve in my shoulder pulling my rollaboard off the hotel van in SYD? I can't raise my arms.

 

Maybe they'd let you stay? Let is know if that happens -- we'll be right there!

 

And causes an involuntary extension of the middle digit on both hands.

 

RadioGirl -- Thanks for your response to my question. I still have a gut feeling that it can't be beneficial to my health to get inside a machine like that -- I tend to get a headaches if I stand too close to the microwave, TV, or use a cell phone for more than a few minutes (and the headache is usually right where I hold the cell phone), but I'm certainly willing to accept that my concern is not based on scientific data.

My biggest problem, too, is that the way the TSA initially forced this stuff on us -- no public comment period, no imminent threat requiring body scans, no testing of the backscatter, no ATR on the MMW, punitive prison frisks for those who opt out, etc. For me, the MMW is suspicious by association. The TSA's overall motives and methods since they brought out the machines have been so much about power and control (h/t Lisa) and so little about aviation security, that I can't help but suspect that the MMW is somehow a sinister piece of machinery. After so much lying and thuggery, I feel like I'm owed something to regain my trust, and some independent testing of these machines on human subjects would be a good start.