According to the Encyclopedia Britannica, the Van Allen belts are most intense along the equator, and effectively absent over the poles. They dip to 400 km over the South Atlantic Ocean, and are about 1,000 km high over the Central Pacific Ocean. In the lower Van Allen Belt, the proton intensity is about 20,000 particles with energy above 30 MeV per second per square centimeter. Electrons reach a maximum energy of 1 MeV, and their intensity has a maximum of 100 million per second per square centimeter. In the outer Belt, proton energy averages only 1 MeV. For comparison, most charged particles discharged in a nuclear explosion range between 0.3 and 3 MeV, while diagnostic medical X-ray has peak voltage around 0.5 MeV.