# I'm sleeping with my head in a 6 milliGauss AC magnetic field.January 1, 2017 9:29 AM   Subscribe

So there's a powerline outside my bedroom window, and I thought, huh. Turns out I'm sleeping with my head in a 6mG AC magnetic field. Help me use physics to stop caring.

I poked around in the actual peer-reviewed literature, and I'm not convinced this isn't subtly degrading my quality of life or fractionally increasing my risk of Alzheimers or cancer or something.

So, here's my question:

How do I estimate/calculate which puts more force on the charged particles (calcium, potassium, sodium) in my brain: a) An aqueous solution at 98.6 degrees Fahrenheit or b) a magnetic field acting on charged particles moving at some estimated speed in said aqueous solution.

My hope here is that the force of (b) is like an order of magnitude or two, or something, below the "noise floor" of (a) and then I can stop caring forever.

I emailed my physics grad student friend and he wrote back a cryptic thing with the Boltzmann constant and Planck's constant and strong priors. I am not completely overwhelmed, but still... Help?
posted by zeek321 to Science & Nature (8 answers total) 4 users marked this as a favorite

The Earth's magnetic field ranges from 0.25 to 0.65 G, per Wikipedia. The strength you're talking about is negligible.

You're fine.
posted by steady-state strawberry at 9:40 AM on January 1, 2017 [12 favorites]

I'd be interested to know how you calculated that field strength, or did you measure it?

If you calculated it, what did you assume to be the current carried by the powerline and how far is it from your head? 6mG is about what you'd get from a single wire carrying 10A 3m away; field strength around a single long conductor is proportional to current and inversely proportional to distance from the wire. But if the powerline has multiple conductors, it's a fair bet that those carry different AC phases and that most of the magnetic field strength around them will be in the gap between them - the field tends to cancel out, not just fade, as you get further from the conductor bundle.

Also possibly of interest.

posted by flabdablet at 10:24 AM on January 1, 2017 [3 favorites]

I'm not convinced this isn't subtly degrading my quality of life or fractionally increasing my risk of Alzheimers or cancer or something.

All electricity generates EMF fields. The earth's EMF field (caused by molten lava!!) is running through you right now. You got more EMF exposure sitting under fluorescent lights in school all day as a kid than you are getting at night from that power line. This is well-studied and there's no known health risk.

If you really want to improve your quality of life, go to the doctor and get on an SSRI for anxiety instead of spending any more time calculating the strength of various EMF fields. You're THAT deep in chem trails territory. I'm completely serious.
posted by Snarl Furillo at 11:20 AM on January 1, 2017 [18 favorites]

PS: I don't mean "If you think EMF fields are dangerous, then you MUST be crazy, lol." I mean, "Physiological symptoms of anxiety actually precede anxiety-supporting cognitions in people with clinical anxiety disorders, so if your brain is attributing your anxiety to something omnipresent, unchangeable AND demonstrably non-hazardous, it's probably because your anxiety is omnipresent and unchanging."
posted by Snarl Furillo at 11:36 AM on January 1, 2017 [5 favorites]

Response by poster: I measured it with two different meters.
posted by zeek321 at 12:53 PM on January 1, 2017

To get noticeable neuropsychological effects in TMS, one uses field strengths of about 2T which is about 300 times stronger than what you measured, e.g. somewhere between two and three orders of magnitude difference. And it's probably much much safer than this for other reasons, e.g. the B field in TMS is focal spatially and has an impulse waveform in time, whereas your measured B field is neither and thus not causing focal eddy currents. Sleep well.
posted by soylent00FF00 at 3:37 PM on January 1, 2017

Oops - Unit fail, I calculated it as if you said 6 milli Tesla, but you said 6 milli Gauss. Ten thousand Gauss equals 1 Tesla. So it's actually 4 orders of magnitude safer. The fields used clinically in TMS are 2T or 20,000 Gauss, or about 3 million times stronger than your measurement.
posted by soylent00FF00 at 3:44 PM on January 1, 2017 [1 favorite]

actual peer-reviewed literature,

Unfortunately, there's nothing really preventing a group of people pushing an agenda from creating a "scientific journal", sending their papers and studies to each other, and then publishing the results as "peer-reviewed." Where the literature was published is important - in The Lancet is one thing, in "The Journal of Electromagnetic Health" (a publication I just made up) is quite another. And if you're finding these papers online, you've got even less of a guide for how legitimate they are.

Furthermore, "peer-reviewed" is just one part of the scientific process. In a lot of ways, it simply indicates that a group of experts have found no glaring mistakes and that the data supports the conclusion. The peer review process is not designed to catch fraud or fake data, and even thoroughly vetted papers are not necessarily correct. Once a peer-reviewed paper is published, everyone in the relevant scientific community can read it, and very often other scientists can and will have concerns and reservations about the methods of the studies and the conclusions the paper comes to, and they can and will express those concerns - through editorials, through letters to the original journal, through their own published papers that contradict or disagree with the paper under consideration.

Then there's the matter of replication - part of the point of publishing peer-reviewed papers at all is so other researchers have the information to duplicate a study or experiment and see if they get the same results and come to the same conclusions. Sometimes they don't. Often studies may not be exactly duplicated, but multiple researchers have conducted a variety of similar studies, in which case other researchers may conduct a Systematic Review or Meta-analysis, where a variety of similar-but-not-exact-duplicate studies are examined to see if there is an overall consensus that can be drawn.

In short, you personally taking a look at some peer-reviewed papers is simply not a robust enough method to decide if there's an actual problem. You're not getting enough information, and have no guide to the quality of the information you're finding.

I emailed my physics grad student friend and he wrote back a cryptic thing with the Boltzmann constant and Planck's constant and strong priors.

Well, this is information you need if you really want to compare your "a" to your "b". I mean, I don't have the tools to figure out that comparison, but I know enough to know that those constants will be relevant. If you're finding this too cryptic, I would gently suggest that you don't have the tools either. So maybe your plan for determining if you've got a problem is not the best.

Turns out I'm sleeping with my head in a 6mG AC magnetic field. Help me use physics to stop caring.

Speaking of meta-analyses, here's the World Health Organization's overview of EMF. From the second page:
In the area of biological effects and medical applications of non-ionizing radiation approximately 25,000 articles have been published over the past 30 years. Despite the feeling of some people that more research needs to be done, scientific knowledge in this area is now more extensive than for most chemicals. Based on a recent in-depth review of the scientific literature, the WHO concluded that current evidence does not confirm the existence of any health consequences from exposure to low level electromagnetic fields.
And then if you look at page 4, there's a table giving some magnetic field strengths of various household appliances at various distances - from which you can see that Snarl Furillo is entirely correct about fluorescent lights and that people using hair dryers and electric shavers could be exposed to 1500 to 2000 milliGauss. Yet people are not just keeling over dead from blow-drying their hair.

On top of that, working off flabdablet's link, I would point out that every single electrical wire and outlet in your home is capable of carrying either 15 or 20 amps. While there needs to be current flowing to create a magnetic field, it's possible (even likely) that your readings have far less to do with a major power line outside your house and far more to do with living in the modern world.

So just basic electromagnetic physics - plus the fact that we're not walking around all astounded at how much longer people used to live back in the 1700's - should be enough proof that neither the power line outside your house nor the 6 milliGauss you've measured are having a negative effect on your health. No need for any complex calculations and comparisons.

(And I would gently echo Snarl Furillo in that your concern over this bit of Internet-fueled borderline-conspiracy-theory plus your request for a specific method to "disprove" the supposed effects are a little disturbing. I think you could see great benefits from talking with a professional about how you came to be concerned about this and how you are reacting to this concern.)
posted by soundguy99 at 4:00 PM on January 1, 2017 [6 favorites]

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