What unit is used to describe ionization in air?

What unit is used to describe ionization in air?

• A. Gyt
• B. Gya
• C. Sv
• D. None of the above

Answer: (B)

Ionization in air is tied to how much energy is deposited in air per unit mass. The appropriate unit for that in modern SI terms is Gray in air, written as Gy_a or Gya. This distinguishes it from Gray in tissue (Gyt), which measures absorbed dose in tissue, and from Sievert (Sv), which expresses dose equivalent rather than the raw energy deposition. Historically exposure in air was measured in roentgens, but for current practice the unit describing ionization in air is Gya.

Ionization in air is tied to how much energy is deposited in air per unit mass. The appropriate unit for that in modern SI terms is Gray in air, written as Gy_a or Gya. This distinguishes it from Gray in tissue (Gyt), which measures absorbed dose in tissue, and from Sievert (Sv), which expresses dose equivalent rather than the raw energy deposition. Historically exposure in air was measured in roentgens, but for current practice the unit describing ionization in air is Gya.