Due to the Earth's magnetic field and the barrier of the atmosphere, the vast majority of cosmic rays have dissipated by the time they reach the Earth's surface, resulting in minimal impact on the human body. However, the higher the altitude at which people are located, the more cosmic radiation they will receive. Studies have shown that for every 2000 meters increase in flight altitude, the dose of cosmic radiation exposure to the human body doubles.
The unit typically used to measure radiation dose received by the human body is millisieverts (mSv). Bi YanYan explained that for people living in low-altitude areas, radioactive nuclides in the earth's crust are the main source of background radiation, hidden in soil, rocks, and oceans. The average background radiation in China is about 3.1 mSv.
