Talk:Specific absorption rate

message: Why is the hazards discussed in relation to a pure technical measurement unit? I think that that discussion should be moved to the "Electromagnetic radiation hazard" page.
:I will give it a graze period and then remve the hazrd discussion. I do not think that it belongs here either.Mossig 21:22, 25 April 2006 (UTC)
replies: text: So why aren't the units sieverts per second?  Gene Nygaard (talk) 12:46, 29 November 2007 (UTC)
replies: text: It could be, but as sievert are mainly used for ionizing radiation SAR from RF-fields are described as measured in W/Kg. I have never seen SAR used as a unit, as proposed above. Mossig (talk) 20:19, 29 November 2007 (UTC)
replies: text: Thanks.  I figured it was something like that, but I'd forgotten how to characterize it.  Gene Nygaard 22:57, 30 November 2007 (UTC)

text:  The unit Sievert is only used for ionizing radiation and it includes already a biological weighting factor (for ionizing radiation).  — Preceding unsigned comment added by 147.142.107.30 (talk) 10:03, 29 October 2014 (UTC)
thread_title: Untitled section

message: I've just added a bit more detail on European SAR limits. I have quoted directly from IEC-60601-2-33:2002 for the MRI limits, but I don't have access to IEC 62209-1 (handheld devices) - could somebody who has the standard check that 2W/kg is accurate? I have also hidden the reference to the ICNIRP limit -- I don't think this is considered current, but again, I'd like to have someone confirm. Finally, does someone out there know the FCC/FDA SAR limits for MRI? GyroMagician (talk) 16:34, 8 November 2008 (UTC)
replies: text: Why souldnt the ICNIRP limit be considered current? I will unhide the link to ICNIRP, as this still is the basis for most of the worlds regulations. And I am sceptical about quoting technical standards, such as the MRI standard, direct without the rest of the definitions. It is to little information to be really useful, and to much to give any insight into the matter for the curious reader. Mossig (talk) 00:04, 9 November 2008 (UTC)
replies: text: Okay, I wasn't sure about the ICNIRP limit, I though IEC standards had superceded it - thanks for correcting. Which definitions do you think are missing from the MRI SAR limits? Maybe I should remove the 1st/2nd controlled level limits and only quote the normal operating limits? Or maybe you would prefer to see the MR limits on the MR page? I would also like to try and give some context to the ICNIRP line - it seems rather 'hanging' at the moment. Input welcome. GyroMagician (talk) 11:45, 10 November 2008 (UTC)

text: Good question. SAR is usually used to give an indication of the amount of heating caused by a device. If you deposit too much heat, you start cooking tissue. But if you stay below some limit, it is generally assumed that the heat will dissipate, and no permanent damage is done. For example, IEC-60601 assumes that if the heating stays under 1°C, no damage is done (you can experience a higher temperature rise with a fever, so this seems reasonable). But SAR by itself only measures energy is deposition, over a given time. In principle it could be used to prescribe limits based on concerns about low-level 'background' EM radiation, with an averaging period of years rather than minutes, although I have never seen it used this way. GyroMagician (talk) 19:22, 27 June 2010 (UTC)
thread_title: SAR Limits

message: Local SAR is commonly measured/calculated over 10g (IEC) or 1g (FDA) of tissue. This is confusing because the integral of (sigma * E^2/ rho) is taken over a volume, not a mass (check the units). In simulation (FDTD and similar) this is done by expanding a volume around the calculation point until it contains the required mass. I've modified the wording of the article to try to capture this - is it better? GyroMagician (talk) 06:57, 29 June 2010 (UTC)
thread_title:  Volume/Mass 

message: Hope I'm not off-topic, but these lab measurement don't seem to say anything about the actual compling between the user's hand and head to the emission object, that is the hand-held cell phone.
I learned a long time ago after many years as a radio amateur that the coupling to the body is of keen importance at these microwave frequencies.  
Witness the Iphone 4's bad reputation due to the placement of the feed to two separate antennas in the natural grip point of a right-handed user, which causes a weakening of the emitted field, and dropped calls with resulting bad PR.
This coupling effect is included in the calculations of the designers; and must be met if the impedance and emission pattern is to be the desired one.  This is not always true for all antenna designs, for example: fractal antennas are often least affected as their feeding impedance is already so low, whereas stub or frame antennas are most affected. See iPhone 4 which uses a frame antenna.  Rumors say that their next model will have a metal backplane as one antenna.
My point in this all, is that assigning "safe" and "unsafe" gradings are worthless and may be completely incorrect as to the effect on the brain.  Secondly, at these frequencies there often occurs hot spot anomolies, which could be much higher than than measured or calculated average over a unit the size of the brain.  Witness the unevenness which plagued the first generation of microwave ovens.
I would have proposed instead a measuring system based upon a "in-ear" sensor unit with a shielded (coax) cable to the measuring unit.  Whether the sensor could be placed in actual human user's ears is another question; but see no reason why not----as we after all are using cellphones meant for intensive consumer use.
I perhaps unnecessarily add that I have a degree in EE from NC State University, but claim no expertise in modelling in a lab environment---although have done some practical work but in the 2--30 Mhz range.
Thanks for any guidance to a newbie at Wikipedia.
Idealist707 (talk) 21:42, 1 June 2011 (UTC)
thread_title:  Lab measurements versus practical antenna operation 

message: Can somebody who knows more than I do about this matter add something about what the difference between the EU SAR measurement and US SAR measurement means in practice. It now explains that one is measured over 1g of tissue and the other over 10g, but says nothing about what that difference is measuring actually means. It is clearly not just a different scale, as the difference between the EU SAR and US SAR on the same phone varies.
If Device A has a higher US SAR rating ccompared to Device B, but a lower EU SAR than Device B, what is the actual difference between the devices for the radiation dose of the user? Does it mean that the "worst 1g spot" on the user's head gets more radiation using Device A, but over a larger mass (10g) the total dose is lower, so the radiation absorbion is more concentrated on a specific spot using Device A but less on total, or what? And if so, how is it possible that some phones have a higher EU SAR rating than US SAR? And how is it possible that some phone have a higher US SAR value than EU SAR value, if the US standards should measure the maximum value over a smaller mass?
--86.50.106.241 (talk) 13:13, 23 April 2012 (UTC)
thread_title:  Practical difference between US SAR and EU SAR? 

message: Is this list useful? To be trustworthy every entry needs a reference required and that is clearly impractical.
The article is about the definition of SAR not the SAR of every item that people can think of.  All that is needed is a single entry saying that the SAR of a mobile phone is in the range of 0.5 - 1.5.  — Preceding unsigned comment added by Mtpaley (talk • contribs) 00:12, 16 February 2013 (UTC)
replies: text: As I believe is now obvious to all, the SAR values are verifiable in the FCC database; so one reference to the database suffices.  Viper last two edits were both removed the list at least twice.  Is this the talk page section you're referring to, or are you referring folks to a deleted page, or what?  Link, please.  I won't speculate as to what the real reasons some folks oppose the list are, but it seems like a 'see what sticks' approach is being tried.  I can't think of a COI that would provide such evidently strong motivation.--Elvey (talk) 00:37, 12 December 2013 (UTC)
replies: text:  The individual SAR's can be listed in their respective infoboxes. I personally think that here, its merely trivia, as it does not discuss the SAR's of any other products. ViperSnake151  Talk   20:31, 22 December 2013 (UTC)
replies: text: I don't see an argument there, just unsupported opinion.   I don't see an offer to merge it to infoboxes either.  (I do see the argument that the information is not verifiable, but that's been thoroughly debunked.)  I've added some commentary from the FCC, which I think provides some useful context that a bare, stand-alone list doesn't offer.  WP:IDONTLIKEIT isn't policy and you shouldn't be making that argument in this or any deletion discussion.   --Elvey (talk) 23:40, 22 December 2013 (UTC)

text: Ivan, you're wrong, in that the list was created here first.  It was then sneakily deleted, out of process.   For a role in which, IIRC, Mtpaley apologized.  I don't think the OS is POV pushing; I think it's an artifact of the delete any such list; throw every excuse we can come up with POV pushing.  But we agree, there's no need for that column.  --Elvey (talk) 22:04, 2 January 2014 (UTC)
replies: text: I see that it was created here first. I shouldn't have said that it was being "recreated" here; that implies an end-run around AfD, and that wasn't my intent. My POV concern was that only unlocked Android phones were listed, and there was a WP:WEASELy blurb that seemed to be pushing Replicant, but that has all been resolved by adding more phones and removing the two columns. I don't object to the OS being indicated, I was just concerned that there was only one. Ivanvector (talk) 23:06, 2 January 2014 (UTC)

text: I don't understand what it is that you would support.  A list that has just one entry for all phones, with  1 W/Kg as the combined/averaged SAR for that entry?  With what as the RS?  --Elvey (talk) 22:04, 2 January 2014 (UTC)
replies: text: Obviously, we couldn't include a "back-of-the-envelope" calculation but ideally there are tests published for other types of devices. I'm not an expert in this, I don't know where to look. Ivanvector (talk) 23:09, 2 January 2014 (UTC)

text: Ivan, I'm disappointed that you re-raise the idea that we don't have a RS, as the FCC was provided as an RS for the SAR values, and updated list of 20 lowest radiation cellphones was provided by Enric Naval as a list of the 20 lowest radiation cellphones.  The idea seems discredited to me.  No?  --Elvey (talk) 22:04, 2 January 2014 (UTC)
thread_title:  Mobile phone SAR list 

message: :Category: has been nominated for . You are encouraged to join the discussion  on the Categories for discussion page.
I decided to add the proper notice here too. Please comment on the CfD page. Ivanvector (talk) 18:52, 31 December 2013 (UTC)
thread_title:  CfD nomination of [[:Category:{{ucfirst:Low-radiation smartphones}}]] 

message: I found unhelpful this article without the comparision between several devices (cell phones, WiFi, incandescent light bulb, power lines, etc.) and natural ocurrence (like solar radiation). But I only found the SAR for cell phones, and W/m2 for the others. If anyone can get the data I'd appreciate it.<DIV align="right">Eloy (talk) 07:15, 28 March 2014 (UTC)
thread_title:  Comparision 

message: User JIA329 has made a few edits talking about SAR and eyeglasses. The reference provided is not accessible, so I have added a  template. I can find this article online, which is perhaps the source. However, the article is poorly written, is a computer simulation without experimental confirmation (and so preliminary), and is not indexed in PubMed. Without more solid confirmation, the paragraph should be removed. --papageno (talk) 22:01, 15 April 2015 (UTC)
replies: text: No comment about the quality or verifiability of the reference, but even if it is legit, it definitely does not belong in the header of the SAR article where it is currently placed. If the reference is verified and deemed to be relevant, I would suggest changing the "Criticisms" section to "Criticism and Limitations" or something similar and include it there. --EvilTwinSelf (talk) 11:14, 28 May 2015 (UTC)
thread_title:  SAR and eyeglasses 

message: ::Article: "Specific absorption rate (SAR) is a measure of the rate at which energy is absorbed by the human body..."
::... except when it's absorbed by mice and rats in experiments. The calculations differ for these creatures (unfortunately, in a way that I do not have the expertise to edit into the article). 92.3.210.192 (talk) 16:18, 15 July 2018 (UTC)
thread_title:  Not just humans 

message: SAR values are averaged over time. I do not believe this is adequately mentioned in the text. A footnote to the MRI table does mention six minute averaging, but there should be mention made in the lede, and in the mobile phone section. I believe the time averaging period is six minutes for mobile phones as well, per ICNIRP 1998 (reference is in the article). I also know that the time average period is six minutes in Canada. --papageno (talk) 21:48, 13 October 2018 (UTC)
thread_title:  Better inclusion of time averaging 

message: I'm not an expert but my understanding is that CENELEC doesn't set the exposure limits--it sets standards for testing. My understanding is that the European Council sets the limit in the EU (i.e. 1999/519/EC, which EUR-Lex says is still in force), based on recommendations by the ICNIRP. My understanding is also that CENELEC sets standardization of methods of the measurement of SAR, not the limits. The publicly available 1999/519/EC document could serve as a reference for these two points: The introduction and conclusion discuss the fact that the document is based on the recommendation of the ICNRP and point (12) discusses the role of CENELEC. Thanks
MyIpIsLocalhost (talk) 21:19, 28 February 2024 (UTC)
thread_title: EU regulatory landscape