A Cubic Feet Per Minute (CFM) is a measure of the volume of a substance flowing through air within a fixed period of time. With regard to indoor air, refers to the amount of air, in cubic feet, that is exchanged with outdoor air in a minute's time; i.e. the air exchange rate.
This unit is a non-standard unit and should not be used outside the USA. For international documents you should use Cubic meter (m_) per second according to the international SI-System.