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From Wikipedia:

Some national radiation advisory authorities... have recommended measures to minimize exposure to their citizens... Do not use telephone in a car without an external antenna

I'd wager most people take this advice to mean don't talk on the phone while inside the car. However, to me it sounds like the above also implies don't use GPS navigation apps, at least not apps that constantly communicate with the server (e.g. for traffic reports).

Does this make sense? I guess it depends on the amount of data sent to and from the server?

rjzii
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t0x1n
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    Note, GPS receivers are *receivers*. They don't transmit. No, not even a little. I other words, this question is founded on a bogus assumption. – dmckee --- ex-moderator kitten May 01 '13 at 21:02
  • @dmckee: You can't read. "at least not apps that constantly communicate with the server (e.g. for traffic reports)" – Flimzy May 01 '13 at 21:56
  • I'd loosely estimate that my trips that involve Sat Nav are 5% shorter than if using a paper map, and involve far less higher-risk maneuvers like u-turns, last-minute lane changes, and looking away from the road for more than a second. I'll take the reduced risk of being injured in a crash over the still-no-good-evidence-despite-years-of-searching risk from phone radiation, thanks. – Oddthinking May 01 '13 at 23:00
  • Some of the traffic reports on Garmin navigation units were broadcast on subcarriers of large local FM radio stations. On cellphones there might indeed be some back and forth with the server. However, having the phone in a holder on your dash means you absorb less radio waves when it transmits than if it is up against your ear. And the phone's transmitter is fairly low power (a few watts) and licensed by your country's regulatory authorities, so why all the irrational fear? – Paul May 02 '13 at 02:30
  • @Paul I would not call a fear induced by an official recommendation given by the ministry of health irrational... Even though the phone is not against your ear, as I understand it the car metal surrounding it bounces a lot of the radiation back into the car (possibly harming all passengers). For a similar reason it is not recommended to talk inside an elevator. – t0x1n May 02 '13 at 07:51
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    @t0x1n "Some national radiation advisory authorities..." is not a definite reference. Can you provide a more specific citation? People are picky about that kind of thing here, and it helps in evaluating the credibility of the specific source, – Paul May 02 '13 at 08:42
  • @dmckee not quite true. ALL antennae have an EM field when powered up, even those not actually used to transmit. Of course the field strength is so small it can be safely ignored in this context, but it's there. And the emissions from a cellphone are small enough they too can be ignored, yet idiots and conspiracy theorists keep rambling on about how dangerous they are and that they cause cancer. – jwenting May 02 '13 at 12:01
  • @Paul conspiracy theorists and other idiots will always seek reasons to get people to don their tinfoil hats. Been planning for some time to start a business selling them over the internet... – jwenting May 02 '13 at 12:04
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    aren't we at capacity for cell phone cancer questions yet, every one has the same answer. – Ryathal May 02 '13 at 12:13
  • @Paul - The Israeli ministry of health (if you read Hebrew: http://www.old.health.gov.il/pages/default.asp?PageId=4408&catId=838&maincat=46 ). Also, as per the Wikipedia page, at least some European countries. – t0x1n May 02 '13 at 12:44
  • @Ryathal this is a fairly specific question. I'm not asking if cellphone radiation is bad or not. I'm just trying to determine if data use radiation is different than voice call radiation, specifically in the case of GPS navigation programs. – t0x1n May 02 '13 at 12:46
  • The only thing different about this question and this previous question http://skeptics.stackexchange.com/questions/10112/are-train-passengers-exposed-to-dangerous-levels-of-cell-phone-electromagnetic-r?rq=1 is the size of the box the passengers are in. There is no notable risk. – matt_black May 02 '13 at 20:32
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    @t0x1n The radiation emitted by phones doesn't depend on what is being transmitted (voice or data or GPS): it is all data. – matt_black May 02 '13 at 20:35
  • @matt_black - thanks for both the link and the clarification! – t0x1n May 02 '13 at 20:50
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    If you're using satnav app, then your phone is somewhere on the dashboard. Which means two things: First, it's not next to your head, amount of exposure drops with the square of distance. Second thing, there is no metal to block the signal, it's glass which is pretty much transparent to microwaves. Modern passenger car is hardly a Faraday cage. – vartec May 04 '13 at 12:13
  • @vartec radio waves are transmitted in all directions (http://www.hpa.org.uk/web/HPAweb&HPAwebStandard/HPAweb_C/1195733844923) so even when on the dashboard, some of it will bounce back – t0x1n May 04 '13 at 17:32

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There is some logic here, but there is nothing definitive:

  • Any phone application that uses data connectivity which include many GPS apps. will cause the phone to communicate with the cell tower, and since the car is essentially a faraday cage, that will be in a relatively high wattage when an external antenna is not used.
  • The type of radiation is non-ionizing, and there is little evidance that that type of radiation is harmful - http://www.fcc.gov/encyclopedia/faqs-wireless-phones#evidence
Ofir
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  • Where's oddthinking when you need him? He has a standard response to answers like this, but basically, you need citations here. This website is about eliminating unsupported claims, not making more of them. – Publius May 02 '13 at 11:23
  • Would you say that the data communication is comparable to voice calls, in terms of radiation ? – t0x1n May 02 '13 at 12:50
  • @t0x1n - that depends on the time of data connection and the amount of used bandwidth, it can potentially be higher, but is usually lower for reasonable use (which usually means when not downloading a video). This is due to data use being idle most of the time. A good indication is how much heat is produced by the phone (if not being charged at the time), since most energy is used for transmission (assuming no CPU intensive apps are used at the time) - if the phone gets hotter when using data, it is probably emitting more and vice versa. – Ofir May 05 '13 at 06:24
  • @Ofir I guess I'm trying to understand how the typical data use of a typical GPS navigation app (traffic reports, ads, new routes, etc.) compares to voice calls (and if this can't be answered generally, then specifically for, say, Waze). Will upvote when I hit 15 rep :) – t0x1n May 05 '13 at 10:24
  • @t0x1n - I believe that Waze would emit much less than a voice call for a comparable amount of time, since Waze's data use is relatively low - http://www.waze.com/forum/viewtopic.php?f=3&t=20472 – Ofir May 06 '13 at 05:43
  • @Ofir nice find, that's good to know ! – t0x1n May 06 '13 at 14:56