[SkepticalDebunker (OP)]

I read about 'heliobiology', which is an emerging field of biology studying the effects of solar activity and human health. As it turns out, geomagnetic storms are estimated to cause thousands of heart related deaths each year, with many recent studies finding correlations between geomagnetic storms and heart attacks, arrhythmias, collapse of organ function and death, seizures, strokes, schizophrenia, Alzheimer's, and even sudden cardiac death. Most of the studies showing links between fluctuations in Earth's magnetic field and heart attacks, strokes, etc have been conducted within this decade. Some scientists theorize that these negative health effects are caused by the pineal gland being affected by fluctuating magnetic fields.

During a geomagnetic storm the fluctuations compared to Earth's magnetic field strength are tiny (at most around 500 nanotesla of fluctuation) and happen over the course of minutes to hours. The magnetic field strength of Earth is between 150 and 400 times weaker than a refrigerator magnet. Given the effects Earth's magnetic field has on people's hearts, what would happen if I rapidly waved a fridge magnet past my heart? Would it disrupt the electrical signals in my heart and cause it to stop?

[Kryptid]

Given the effects Earth's magnetic field has on people's hearts, what would happen if I rapidly waved a fridge magnet past my heart? Would it disrupt the electrical signals in my heart and cause it to stop?

I doubt it's that simple. People do enter MRI machines without having heart attacks, for example.

[evan_au]

Geomagnetic storms can induce damaging high currents at low frequencies (<0.1 Hz) in long conductors like electrical transmission lines and oil pipelines.

These high currents originate from voltages induced between points on the Earth's surface thousands of km apart.
- However, your average human rarely stands with their feet more than 1 m apart
- And dry skin is a fairly good insulator for voltages up to around 30V
- In Western countries, most people have insulating soles on their shoes.
- So low-frequency electrical currents are unlikely to be to blame.
https://en.wikipedia.org/wiki/Geomagnetically_induced_current

To pick up an electromagnetic signal efficiently, you need an antenna on the same order of magnitude as the electromagnetic wavelength
- Since the human body has a dimensions around 1-2 m, but these wavelengths are >3 million km, one could assume that there is very little induction into the human body.
- It would need to be > 50mV to have any impact on the functioning of nerves and muscles.

Probably, a fridge magnet in contact with your body would induce greater voltages and currents in your body than a geomagnetic storm with much lower frequencies.
- However, a fridge magnet has alternating N/S poles (a Halbach array)
- One side has almost no magnetic field - no damage to humans
- On the other side, there is a much stronger field, but the alternating poles means that the field rapidly drops to zero with distance; it would not penetrate more than a couple of millimeters under your skin. Not enough to damage nerves, heart, or other muscles.
https://en.wikipedia.org/wiki/Refrigerator_magnet#Halbach_array_polarization

If humans had some subtle sensitivity to magnetic fields (as pigeons are believed to possess), then perhaps humans may be disturbed by a subconscious sense of vertigo, when the magnetic field changes orientation slightly?

There is an economic term "sunspot": It implies a correlation between sunspots (and implicitly solar storms) and economic activity.
- Despite multiple people searching for such a correlation, they have (so far) turned out to be spurious when examined with more data
- With several satellites watching the Sun continually, perhaps now we can get a better correlation between solar activity and sudden death - or will it also turn out to be a spurious correlation?
https://en.wikipedia.org/wiki/Sunspots_(economics)#Origin_of_terminology

[alancalverd]

You can indeed induce significant currents in long nerve fibers or blood vessels with alternating magnetic fields but AFAIK MRI  gradient slew rates of 200 T/m.s are not associated with heart attacks.

Some idea of the rigor of biogeomagnetic research can be gained from studies of the effects of magnetic fields on the migratory behavior of European robins. Research from Sweden indicated significant disruption of their navigational ability, but this was disputed by German researchers who could not replicate the result. The controversy was resolved by ornithologists pointing out that robins are territorial, so temperate (including German) robins do not migrate, but arctic robins have to. Evolution got there first!   

[paul cotter]

In the us the fda places limits on two mri parameters: the maximum rf energy per unit volume to avoid heating effects and the maximum rate of change of the magnetic field to avoid involuntary muscle stimulation(via spurious nerve signals). A fast enough changing magnetic field will induce sufficient voltage in nerve tissue to cause false triggering. PS I quoted us regs and I am sure there is the equivalent in Europe.

[alancalverd]

The same limits apply pretty well anywhere, and there are also statutory limits on the exposure to static and alternating magnetic, electric and electromagnetic fields at work. But these are all several orders of magnitude greater than the effect of sunspots or the shifting magnetic poles.