Table 1 Important radiological parameters and indices^22,23.

D_air (nGy h⁻¹)

The radioactive factor known as the absorbed dose rate was used to evaluate the effect of gamma radiation at a distance of 1 m from radiation sources in the air owing to the concentrations of ²³⁸U, ²³²Th, and ⁴⁰K

D_air (nGy h⁻¹) = 0.430 A_Ra + 0.666 A_Th + 0.042 A_K

AED

An element of radioactivity called the yearly effective dose is used to gauge radiation exposure levels over a fixed period of time (1 year)

AED (mSv year⁻¹) = D_air (nGy h⁻¹) * 0.2 * 8760 (h year⁻¹) * 0.7 (Sv Gy⁻¹) * 10^–6 (mSv nGy⁻¹)

ELCR

The radioactive factor used to determine whether gamma radiation exposure caused lethal cancer is called excess lifetime cancer

ELCR = AED × DL × RF