Environmental, Filtration Engineering Ltd, Air Filtration, Air Quality Control Systems, UK

The air around us contains millions of particles in every cubic metre. The majority of the particulate in the air is generally below one micron in size and a high percentage of dust can remain airborne even in still air. A relatively quiet office environment will contain >1.5 million particles per cubic metre, rising considerably where there is concentrated human activity - such as a shopping complex. A busy environment such as a motorway offers particulate levels which are too high to be measured using conventional (clean room) particle counters. The majority of the dust in the air is the result of incineration and in urban areas the carbonitious content is high. Motor vehicles, town waste incinerators and power station emissions make up the main source of particulates in the atmosphere. There may also be agricultural dusts and of course microorganisms such as yeast, moulds and bacteria (hosted). Urban and rural air quality may vary with the prevailing wind. However, there is no general level of air cleanliness we can expect for urban or rural environments.

Air filtration is designed to remove particulates and microorganisms from the air using a variety of mechanical processes. The degree of air filtration is selected by evaluating the risk of the contamination. Air filters are tested for efficiency using one of two tests which are designed to reflect the operating performance requirements, thus the air filtration system is the first critical control point in the air quality control process for both environmental and process applications in the food industry.

Particulate and microbiological control will be linked with one or more services, such as heating, cooling and dehumidification to meet the supply air needs for process control and personnel comfort.

In order of importance air quality control and food process containment is considered somewhat down the list of priorities to ensure safety of the food manufacturing process. The order of importance is not for discussion here and the principle of maintaining minimum standards, especially for successful aseptic food processing, cannot be underestimated. It is interesting to note that conditioned air can be in contact with food, processing equipment, product input, packaging, personnel, process cleaning, storage and handling, and yet the air does not play a useful role in controlling the spread of contamination, unless a number of factors such as air distribution and space containment are effectively addressed.

This document does not discuss dust control and dust filtration systems. The subject of nuisance dust applications and their control to conform to COSHH is covered in a further reading from FEL (FEL Technical Note - 122). The latest ATEX regulations are also discussed (FEL Technical Notes – 121 and 125).

Environmental air