自し然ぜん放ほう射しゃ線せん

noun

natural radiation; background radiation

Refers to ionizing radiation from natural sources such as cosmic rays, terrestrial radionuclides, and internal body radioactivity. Often used in scientific, environmental, and health contexts.

• 自し然ぜん放ほう射しゃ線せんは、宇う宙ちゅうや大だい地ちから常つねに私わたしたちの体からだに降ふり注そそいでいる。

  Natural radiation constantly falls on our bodies from space and the earth.

• この地ち域いきの自し然ぜん放ほう射しゃ線せん量りょうは全ぜん国こく平へい均きんよりやや高たかい。

  The natural radiation level in this area is slightly higher than the national average.