All of a sudden, out of nowhere, within the past three years, there have been a myriad of studies all saying that fluctuations in Earth's magnetic field causes heart attacks and other heart problems, due to Earth's magnetic field disrupting the heart's electrical activity. Pretty much every serious health problem you can think of has been correlated with geomagnetic storms.
https://www.sciencedirect.com/science/a ... 2420300080
https://www.ahajournals.org/doi/10.1161/JAHA.120.021006
https://biomedscis.com/fulltext/the-eff ... 000203.php
https://www.newscientist.com/article/dn ... -suicides/
https://www.newscientist.com/article/23 ... iven-year/
This list of links is very non-exhaustive.
I've even seen studies linking fluctuations in Earth's magnetic field (geomagnetic storms) with the incidence of seizures, schizophrenia, and even Alzheimer's. Though some studies don't suggest a mechanism other than "magnetic activity", the ones that do always mention "Schumann Resonances" and how Earth's magnetic field disrupts the "Pineal gland" or "liquid crystals" that are inside every cell, and when Earth's magnetic field fluctuates during a geomagnetic storm, the properties of these crystals are changed, leading to disease. There are occasionally mentions of solar storms altering the frequency of these "Schumann resonances", which then affects human brainwaves and autonomic systems, including the heart.
This is reportedly an emerging field of biology, known as "heliobiology".
So, what about MRI machines? The magnetic field of an MRI machine is a whopping 100,000 times stronger than Earth's, and the fluctuations are much more violent. By comparison, the fluctuations of Earth's magnetic field during even the most severe geomagnetic storms are measured on the order of a few hundred nanoteslas per minute and don't even affect pacemakers.