Cpi is the initial concentration and at a certain point, Cpt is the
concentration at the same point after time T and Ci is the concentration
in the supply.
For any given release rate of gaseous pollutant and ventilation
rate (fresh air), assuming perfect mixing in the space, the rate of
increase of pollutant concentration to the fresh air was also used as
ventilation effectiveness in one study [81].
Another study even developed a dimensional indicator to express
the ventilation effectiveness regarding the contaminant
removal performance of the ventilation system. For example, local
purging flow rate was developed and widely used for numerical
simulation and the “Net Escape Velocity (NEV)” is the new