Sievert

The Sievert (Sv) is the unit (SI-unit) of dose equivalent and effective dose. In general, fractions of the unit of dose are used in radiation protection practice:
1 Sievert
= 1,000 millisieverts (mSv)
= 1,000,000 microsieverts (µSv)
= 1,000,000,000 nanosieverts (nSv).

Dose is often related to a period of time, i.e. per year (mSv/a) or per hour (mSv/h).