Do you assess air quality in your organization? Please share which parameters you control.


Air in food products facilities is a vector of contamination, moving from one place to another, and should be a concern to food safety practitioner’s as well as, for example, contamination by surfaces. Contaminants can be dispersed by aerosols consisting of solid (e.g. dust) or liquid (e.g. condensation water) microscopic particles dispersed in air. These particles may carry microorganisms (bioaerosols) such as pathogenic bacteria or fungi or even viruses, spores or allergenic substances.

Aerosols may enter food production areas by several ways:

  • Drains
  • Doorways and other openings
  • Disinfection tunnels
  • Compressed air supplies
  • During cleaning and washing operations
  • Packaging
  • Poorly designed/maintained air handling systems
  • Roof leaks

Besides that, various processing operations such as dicing, chopping, mixing, etc., generate aerosols, increasing the risk of contamination.


Controlling movement of air and generation of aerosols should be taken seriously


According to Airborne Contamination: A Microbiologist’s Perspective, it’s believed that liquid or solid particles size range from 5 to 20 µm. Particles smaller than 5 µm are expected to persist suspended in the air of a facility for an extended time and may be reduced by fogging with appropriate sanitizer. Particles larger than 20 µm are likely to settle quickly and can be removed by adequate cleaning and sanitation techniques.

Controlling movement of air and generation of aerosols should be taken seriously when planning facilities layouts and even the day-by-day operations, particularly for high risk products.

The relevance of the air system to guarantee an acceptable level of contamination inside food products facilities is proportional to the product’s risk. In the case of low-risk products, such as packaged food products, stable at room temperature and/or subjected to thermal processing by the consumer, the system may have less demanding characteristics (e.g. filtration requirements). On the other hand, in high risk products, such as ready-to-eat foods, the air supply is critical to prevent contamination and control microbiological risks. Mainly in medium and high risk food products’ facilities it is also common to have physically separated areas for some particular steps of the process where the probability of product contamination is higher.

Air systems can control or reduce the risk of product contamination by two different approaches, according to the way they interact with the contamination source:

  1. Indirectly: acting on the conditions (e.g. temperature)
  2. Directly: acting on the sources of contamination (e.g. removing dust)

The design of air systems predominantly influences the contamination risk in four ways.

In some facilities or in some special production areas where overpressure is used, the volume of air introduced by the air system should be enough to guarantee the continuous outflow of air, preventing contaminated air to flow in. In practice achieving this constant outwards flow can be challenge, mainly when doors are opened, and every opening should be taken in consideration when designing the room (e.g. conveyors, drains, light fixtures,…).

The importance of air quality, and particularly of air flow, in preventing cross-contamination was mentioned in June’s article. To be effective, the installation should be designed so that the air flows from the less contaminated areas, typically where finished products are processed, to the more contaminated areas, usually close to where raw materials are received.


All standards mention the importance of maintenance and monitoring of ventilation and air systems


It is also important to take in consideration that the quality of air inside food product facilities impacts the employees comfort and health.

BRC, SQF and FSSC 22000 address air quality on their food safety systems in a dedicated clause (a table that resumes the information about air quality in those systems will be sent to all Food Safety Books Connected members). These clauses mention that air shall be monitored to ensure it does not represent a contamination risk. In FSSC 22000 it is mandatory to establish requirements for filtration, humidity and microbiology of air used as an ingredient or for direct product contact. Maintenance of specified air pressure differentials between two different areas is mentioned in FSSC and BRC.

All standards mention the importance of maintenance and monitoring of ventilation and air systems (filter changing is predicted in all, except SQF). IFS does not mention air quality in particular but has a dedicated clause about air conditioning/ventilation. In the clause about sanitary facilities, the use of adequate ventilation and a mechanical airflow from contamination area to a clean area is referred.

This article was written in collaboration with Gabriela Silva


Disclaimer: The information contained on this article is based on research done in the last months and the authors personal experience and opinion. It is not intended to represent the view of any organization they work for or collaborate with. The authors will not be held liable for the use or misuse of the information provided in the article.

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