It is not uncommon for a critical facility to assume that the contamination inside their facility comes from one particular source, only to find, after testing the contamination itself and analyzing its composition, that the contamination stems from another source altogether. Often one that is unexpected. It could be as simple as you looking in the wrong place: contaminants that one might expect to be found in the under the floor, for example, may not be there, but not because the source of contamination is wrong, but rather that the contaminants have already dispersed on the airflow path and are now on the face of the racks. Contamination can continue to ‘appear’ and build up if left unchecked. It can even reappear after a thorough deep clean. Its best to track the source and remediate the problem before undertaking pointless cleaning.
So-called ‘unexplained contamination’ requires a better understanding of the environment, and intelligent analysis of the data presented. By taking samples and testing them, the mysteries can be explained, and the impact of contaminants properly assessed. Technical cleaning of course has its place; but technical cleaning without recognizing and understanding the source of contamination, is effectively throwing good money after bad.