Well, we just got back from Las Vegas last night. Had a great time, Yeah!.
In Concourse C checkpoint, EVERYONE, except airline employees, had to either go through the body scanner or submit to an enhanced pat down. New toy, so they have to use it I guess.
Anyway, this one was a millimeter wave technology based unit and not the back scatter unit. The back scanner unit uses ionizing radiation so that is a big no-no for anything other than medical tests in my opinion even if it is very low.
Back to the millimeter wave unit. I decided to opt out. I expose myself to all kinds of crap at work and home, why do more. Besides, I guess having a TSA agent look at my junk versus touch it though my clothing is not much different. Also, if they see something “suspicious” you have to have the pat down anyway..
Let’s look at the safety of millimeter wave RF energy. First of which, the TSA agent told me it was sound waves. NOT! It is radio waves in the 30-300 GHz range (EHF). I have not been able to find the exact frequency. Probably classified.
TSA says it is safe:
Problem with this picture that cellphones use a way different frequency than EHF range of the millimeter wave based scanner. For example GSM based cell phones in the US use the 850 MHz and 1.9 GHz bands. No cellphones anywhere use anything in the EHF band of 30 to 300 GHz. Another issue with the picture is that cellphone uses an omnidirectional antenna with little or no gain. I have no idea if the transmitting antenna in the millimeter wave based scanner has any gain. I would think that it is directional and thus would have some gain.
So, the little picture really means nothing other than to keep people happy and ignorant. So the question remains, is exposure to EHF harmful? Hell is exposure to RF harmful. Well yes in large amounts. Well the level is supposed to be small. But since we have no real information, it is hard to calculate. An interesting thing is if one looks in the FCC guidelines in Table 1 in Appendix A of FCC OET Bulletin 65, one sees that they stop at 100 GHz. The millimeter wave scanners are somewhere in the 30 to 300 GHz range. Basically for the general population, the “safe” exposure level is 1 mW/cm squared in the 1.5 to 100 GHz range. This is fairly large compared to the scanner if indeed it is thousands of times less than the cellphone (maxium of 2 watts for GSM). Again, TSA does not give us enough information to calculate the field strength and I suppose I would get in big trouble if I tried carrying a field strength meter through a scanner. Again, if sufficient gain antennas one can achieve that level. There is an amateur radio operator with 1,000,000 watt ERP level from his antenna using 1,500 watt amp. So just because the input level is low, does not mean the field strength is low. And field strength not total energy of the system is the primary concern in RF exposure.
Also, what about malfunctions? What type of safeguards are in there? Finally, some research shows exposure to EHF RF as an stress item. That is, while it does not appear to cause cancer, it may cause tumors to grow faster due to stress on the body.
Unfortunately, I can not direct link to the article as it is by subscription but here is an synopsis:
“Thus, it is clear that RF radiation is not genotoxic and therefore cannot initiate cancer… the majority of such studies have shown that chronic exposure of animals to RF in the range of 435 to 2,450 MHz did not significantly alter the development of tumors in a number of animal cancer models… the same acceleration of skin cancer development and reduction in survival occurred in animals exposed to chronic confinement stress in the absence of RF exposure, suggesting that the RF effect could possibly be due to a non-specific stress reaction.”
Have fun at the airport.