Ground Level Enhancement
These effects are usually measured as elevated levels of neutrons and muons. These events can increase the radiation dose of an individual at sea level or while in an aircraft, though not by enough to significantly increase an individual's lifetime risk of cancer. ...and
"solar wind"
400 km/s x 5 ions/cm^3^ x 1g/mol x ...(6400km)^2^ x 3.1416 x 1e15cm^3^/km^3^
... x 86400s/day x 1/(6.02e23 ions/mol) This is about 37 tons per day, mostly proton and alpha particles.
...
I used the diameter of the earth instead of that of the magnetic field around the Earth, this is simplistic but should give an order of magnitude. I did not find better information and the real value should be found by someone else.

solar wind details inside :

Properties and structure
Velocity and density :
"Near the Earth's orbit at 1 astronomical unit (AU) the plasma flows at speeds ranging from 250 to 750 km/s (155–404 mi/s) with a density ranging between 3 and 10 particles per cubic centimeter and"...

[–] 133arc585@lemmy.ml 2 points 1 year ago

You're right and I completely forgot about those somehow.

For pespective,

On average, Americans receive a radiation dose of about 0.62 rem (620 millirem) each year. Half of this dose comes from natural background radiation. Most of this background exposure comes from radon in the air, with smaller amounts from cosmic rays and the Earth itself.

So, cosmic rays contribute hardly (about 4%) any to the radiation we receive every day.

I'm no expert here, clearly, so I'm not sure how to compare these units of radiation with the ones being provided for the Fukushima water release; those numbers are provided in becquerel from the sources I found.