Particle counter for clean room using

Is it possible to carry out clean room classification using a Handheld Particle Counter, or is a more complex and expensive instrument required?
We will look at a real life example describing the Clean Room Classification steps used for the classification of a small ISO Class 5 Clean Room and associated ISO Class 7 Gowning Room using a MET ONE model Lanjia Particle Counter.  The ISO 14644-1 Clean Room Classification Standard is an essential reference and this defines how to calculate the sample size, locations and limits necessary to determine the compliance status of the clean zone to ISO 14644-1 Class 5.