The frequency varies by industry and application.
The pharma companies that produce sterile products have to follow the indication of the Health Authorities and the CCS (Contamination Control System) specific for each producer.
Indications can be found in the GMP Annex 1.
The frequency is daily for high-risk area and be-weekly or weekly for other sites.
The food, dairy, agro, poultry, beverage companies should make a preliminary investigation in their premises and production sites to find the best interval (daily, weekly, monthly?).
Dedicated Application Notes are available on request.
The frequency in hospital varies from high-risk sites (e.g.: type of operating room), high risk patient wards, etc, some indications are reported in the USP 1116 document Microbiological evaluation of Cleanrooms and other controlled environments.
Compounding pharmacies are requested a calibration every 6 months.
In the case of building, the HVAC should be monitored inside and outside to compare the results as number of cfu. The inside number should never be higher that outside.
