If Option 2 for an air test fails, the remedy is ....

"....conduct an additional flush-out with outside air and retest the noncompliant concentrations. Repeat until all requirements are met. When retesting noncompliant building areas, take samples from the same locations as in the first test, although it is not required."

Does anyone have a good idea how long the additional flush-out should be or the amount of air (cfm) that needs to be moved through the system?