The microbiological contamination load or bioburden for starting materials prior to sterilization should be determined and kept to a minimum. There should be limits specified in specifications and evidence of testing. The microbiological contamination of products should be kept to a minimum. Large volume parenterals should be passed through a micro-organism retaining filter immediately before sterilisation. Where solutions are stored in sealed vessels, make sure that the pressure release outlets are protected with hydrophobic air filters.

There should be a minimum or no containers or other materials in the area, liable to generate fibres due to the risk of contamination.

Extreme care must be taken with materials that have been sterilized in the area for use in aseptic production, such as primary containers and filling machine parts. After removal from the sterilizer, they should be stored in a way which maintains their sterility (examples: in laminar airflow, triple wrapping etc.). All packs should be marked with the date of sterilization and there should be a procedure setting out how long an item can remain in the area before it needs to be re-sterilized. The stage of processing should thus be identified (e.g. proper labelling).