Origin of the contamination in the food processing facilities. Classification of the environmental contamination microorganisms. Study of the lay-out. Description of the possible scenarios of contamination in the food processing facilities. Objectives of an environmental monitoring program. Mapping, traceability and persistence of contamination. Hygiene zones assessment. Zoning concept. Definition of the moment, frequencies and of the procedure to conduct environmental sampling. Definition of the target microorganisms. Conduction of an environmental sampling at a food processing facility and samples processing at the laboratory. Report writing and data interpretation. Definition of possible corrective actions.