This document establishes typical assessment processes to determine grading levels of air chemical cleanliness (ACC) in cleanrooms and associated controlled environments, in terms of airborne concentrations of specific chemical substances (individual, group or category), and provides a protocol to include test methods, analysis and time-weighted factors for their determination. This document currently considers only concentrations of air chemical contaminants between 100 g/m3 and 10"12 g/m3 under cleanroom operational conditions. This document is not relevant for application in those industries, processes or productions where the presence of airborne chemical substances is not considered a risk to the product or process. It is not the intention of this document to describe the nature of air chemical contaminants. This document does not give a classification of surface chemical contamination.