The picocurie (pCi) is $10^{-12}$ of the curie, a non-SI unit of radioactivity. $1\,\text{pCi} = 3.7 \times 10^{-2}\,\text{Bq} = 0.037$ radioactive disintegrations per second. It is commonly used in environmental monitoring, particularly for radon activity in air and water.
Picocurie