product being manufactured the level of clean controlled space is initially determined using the cleanroom classification standards, the higher the risk of contamination the cleaner the environment, e.g., aseptic filling is performed in an ISO 5 controlled environment, whereas terminally sterilized product is finished in an ISO 7 area (prior to final sterilization). The classification of risk also contributes to the type of instrument used. General monitoring on a periodic basis uses portable equipment, moved from location to location as determined by a risk assessment. For more risk critical production these are performed in a machine that isolates the general environment from the process environment, the removal of personnel from the direct area using isolators or RABS increases confidence of control, these machines are monitored continuously using point of sample instruments giving continuous feedback as to the quality of the environment and any contamination events in real time. The primary concern for contamination is risk of adverse effects by the end user, a resultant demonstration of control, is an increase in production. The general environments are also monitored for any microbial contaminants using traditional techniques such as settle plates and volumetric air samplers. Liquid systems Liquid systems are used primarily in a laboratory to demonstrate the absence of particles in finished liquid products. Any particles present may be a contaminant or undesired agglomerations of insoluble product. Liquids for injection have regulated limits for maximum particle concentrations, standards contained within the United States Pharmacopeia (USP), European Pharmacopeia (EP) and Japanese Pharmacopeia (JP) define these limits. Gas systems Compressed gases used in formulation, conveying and overlaying are required to meet the same standards for GMP compliance as all environmental air quality and should be tested at point of use. Particle counters fitted with gas pressure diffusion devices reduce line pressure to atmospheric without impacting the flow path of particles within the airstream, the gas is then tested at atmospheric pressure. Industrial Other industries also use particle counters to control demonstrate either cleanliness of manufacturing environments or quality of finished product, these combine to reduce any additional cleaning processes. Automotive Painting automobiles in clean environments reduces the need to rework defects in paint finishes, particle counters located within the clean areas give continuous feedback to quality engineers ensuring clean conditions are maintained. Engines are built to exacting tolerances are cleaned and assembled in clean areas, using cleaning agents verified using particle counters. Hydraulic