This article is the second of a three-part
series that investigates the application of
the ventilation equations to designing
and testing cleanrooms. This part is
concerned with the decay equation. The
recovery test, described in ISO 14644-3
(2005) is discussed, and improvements
recommended. The application of
the decay equation to the ‘clean up’
requirement given in the EU GGMP
(2008) is also discussed. Finally, a method
is considered that calculates the time
needed for airborne contamination in
cleanroom areas to decay to acceptable
concentrations
