Microporous membrane filters, e.g. cellulose ester, polycarbonate, and gelatin, may be used to collect a sample from a forced volume of air. The resulting filter is placed on or in growth medium and incubated. Applied stresses as a result of desiccation may affect the result.

Glass impingers collect a sample in a liquid reducing stress to the cells and from which further techniques may be applied, e.g. filtration for subsequent cell labeling and laser scanning, PCR.

Impaction methods involve the direction of an air jet onto a solid surface usually a Petri dish containing a growth medium. The air sample is aspirated through a slit or sieve arrangement that in turn affects the velocity of the particles. The carrier air is then deflected away and in some cases measured by anemometers that control the flow rates input by the user. The Petri dish is then incubated and a cfu obtained, for a faster result collection can be onto a water soluble gel or other collection liquid, which can be used in more rapid analytical techniques such as fluoresent labelled cytometry, PCR or immunoassay.

Air samplers have two main components. The sampling head and the control unit/pump assembly. In portable devices such as the AES Sampl'air, EMD MAS 100, BioTrace AirTrace/Spin Air, Millipore M air T, Oxoid M.A.Q.S., and the SAS range from pbi, both these components are integrated. This facilitates the movement of the device from location to location.

For more sensitive, controlled areas the sampling heads can be located remote from the control unit, e.g. the AES Sampl'air MK2, EMD MAS ISO, Millipore M air T for isolators. This allows the sampling head to be subject to the same cleaning and disinfection protocols as the area being sampled. Units offering specific functionality are also available, e.g. compressed gases can be sampled using the EMD MAS CG and BioTrace AirTrace and in explosion risk areas the EMD MAS 100 Ex.

Monitoring of airborne contamination in pharmaceutical production processes is a requirement of many regulatory authorities throughout the world, e.g. FDA, MCA.

It is also adopted voluntarily in many food production environments as a quantitative method for assessment of air as a 'hidden ingredient'.

Successful HACCP regimes will include the diligent monitoring of environmental contaminants. There are also international standards relating to the air monitoring in different environments, e.g. ISO 14698 and ISO 14644. Such standards are beginning to supersede national guidelines in some countries.