Scientists in Brazil have discovered a correlation between solar storms — which cause disturbances in Earth’s magnetic field — and an increase in cases of myocardial infarction (heart attacks), particularly among women. The study results were published in the journal Communications Medicine.

The research was based on data from the public health system of São José dos Campos, São Paulo State, covering the period from 1998 to 2005. In total, 871 cases among men and 469 among women were analyzed. The authors compared these cases with geomagnetic activity, measured using the Kp index (which indicates the level of disturbances in Earth’s magnetic field).

Days with minimal geomagnetic activity were classified as “quiet,” those with moderate activity as “moderate,” and those with strong disturbances as “disturbed.” The analysis showed that although the absolute number of heart attacks was higher among men regardless of geomagnetic conditions, for women the relative frequency of heart attacks on “disturbed” days was significantly greater — especially in the 31–60 age group, where it was up to three times higher compared to “quiet” days.

The authors emphasize that this is an observational study and does not prove a causal relationship. They note certain limitations — the study was conducted in a single city with a relatively small sample size — and highlight the need for further research to confirm or refute the observed link.

According to the researchers, possible mechanisms include the effects of magnetic disturbances on blood pressure, heart rate, and circadian rhythms (the body’s internal “clock”). They also point out that 2025 is marked by high solar activity, meaning such disturbances will occur more frequently.