Clean air can be achieved by tackling it at the source or by cleaning the air. There are many different air purifiers on the market. These are often fitted with a standard filter. But there are also newer, efficient techniques such as air purifiers with ionization. What are the differences and what is important?

A standard air purifier uses a fan to generate a flow of air. The flow of air is then fed through a filter which captures the air pollutants and thus improves the air quality. The smaller the fine particles, the denser the filters usually have to be in order to capture the (risk) particles. An additional focus point is that the filters must regularly be cleaned/replaced. They become saturated as the pollutants accumulate. The fan must work harder, which results in higher energy consumption, reduced capacity and noise pollution. Furthermore, many filters are made of moisture-holding materials such as textile or fibres in which bacteria can start to grow.

Ionization is a newer technique that is developing rapidly. It is an innovation that is being used more and more, if nothing else from the viewpoint of sustainability and energy conservation. There are many air purifiers on the market that use ionization. A distinction can be made between air purifiers that use positive ionization and those that use negative ionization. Ionization (the positive or negative electrical charging of atoms or molecules) generates ions that adhere to particles and thus create charged particulates. It is much easier for these charged particulates to settle of all kinds of surfaces. There is one additional distinction between air purifiers that use ionization, namely those that charge the particles electrically (without filter) and air purifiers that charge the particulates and then immediately capture them.

The former is called open ionization (1) and the latter is known as closed ionization (2):

Open ionization:

The charged particulates are spread throughout the space and find a surface on which to settle on their own. They therefore settle on surfaces such as furniture, ceilings, walls, equipment, as well as in our lungs. These systems create many charged particles but also free ions that are often negatively charged. This is known as negative ionization. Negative ionization also creates unwanted biproducts such as ozone, free radicals and free ions. It is true that these contribute to the reduction of odour, but they are also harmful to our health. Research shows that it is up to five times easier for the charged particles to settle in our lungs when compared to uncharged particles.

Closed ionization:

The charged particles are captured on a special surface within the system itself, so that no particles are expelled into the space and can therefore not settle upon other surfaces. Closed ionization can generate both positive and negative ionization. The surface upon which the particles are captured can be made of various materials, such as conventional filters, metal plates or special open structure filters. The advantage of air purifiers that capture particles with a special open structure filter is that they do not become saturated and less energy is therefore needed to propel the air through the filter. Good examples of air purifiers with an open structure filter are the ASPRA® air purifiers made by VFA Solutions B.V. Some odours are removed by capturing the particles. For specific and focused odour removal, VFA Solutions uses an extra special gas absorption filter directly behind the ASPRA® open structure filters. This gas filtration section is specifically selected based on the type of gasses present, their concentrations and odours and can be different per industry and even per client. Placing VFA gas filters behind the ASPRA® particle filters protects the gas filters from particles so that they are more effective and have a longer life.