This is called background radiation and levels vary from place to place, though the average dose is fairly constant.

辐射强度会因地点而异，但平均辐射量实则大致相同。

youdao

This is called background radiation and levels vary from place to place, though the average dose is fairly constant.

辐射强度会因地点而异，但平均辐射量实则大致相同。

youdao