"Over the last 200 years, the magnetic field has lost around 9% of its strength on a global average. A large region of reduced magnetic intensity has developed between Africa and South America and is known as the South Atlantic Anomaly."
The South Atlantic Anomaly is interesting. In past years satellites are being made to shutdown while passing the regions to avoid damage from the lack of protection from harmful particles.
Not the original commenter but I am in the industry, and its true, many satellites shut down during this region over the South Atlantic.
For that reason, it is not a popular orbit unless there is a larger driver behind the selection. For example the ISS goes right through it in order to be above Russia for a reasonable portion of its orbit. I believe Astronauts have reported increases in optical flashes during this part of the orbit as more energetic particles pass through their eyes.
The South Atlantic Anomaly is interesting. In past years satellites are being made to shutdown while passing the regions to avoid damage from the lack of protection from harmful particles.