There are many air purifiers ...
HEPA filters, UV-C lamps, ozone units, plasma technology – but what's the difference?
Autumn is just around the corner and with it comes the start of school. But it is not only children who will have to spend more time indoors again. From restaurants to association meetings, we need solutions to keep us well protected from infection. One option is units for air purification. In the blog post, we compare popular technologies that vary widely in effectiveness, cost, noise emissions, maintenance requirements, health impacts, etc. You will learn about the advantages and disadvantages of individual technologies and what you should look out for when making a decision.
Let’s begin with a short explanation – what actually are germs? Germs are pathogens. This umbrella term includes viruses, bacteria, fungal spores, algae, parasites, etc.
Centralized or decentralized: 2 ways to disinfect the air
In principle, two basic methods of air disinfection can be distinguished: centralized units (filters, UV-C and ozone technologies) that recirculate the air repeatedly, or decentralized air purification in real time, such as Sterex plasma technology.
As for filtering units, e.g. HEPA filters, what can they do?
Let’s start with the central units. A HEPA (“High Efficiency Particulate Air”) filter, the king among filter units, can filter not only pollen, but also the smallest particles such as viruses. Room air is sucked in, filtered – partly irradiated with UV-C – and then blown back into the room. The following is important: On the way to the central filter unit, germ-laden air flows past people and can cause infections. The filters must be replaced and disposed of regularly with appropriate precautions, as full filters can no longer absorb the viruses and become “virus slingers”. This is by no means a sustainable or ecological solution, as millions of old filters end up in the trash all the time.
Air exchange rate – an unknown quantity?
In the case of centralized units, the question is how long it will take to circulate and disinfect all the air. This depends on the performance of the unit and the size of the room. The rule is: the larger the room and the number of people, the higher the air exchange rate (volume flow in m3/h) must be. This describes how often the total volume of air is exchanged per hour. In classrooms or seminar rooms, state institutes and testing laboratories recommend at least a 4 to 6-fold air exchange rate, or in some cases even higher.
Much ado about nothing
In order to achieve sufficiently effective air purification, a correspondingly high air exchange rate is therefore necessary. This goes hand in hand with an increasing noise level – especially with cheaper units – and only a few units achieve a noise level of < 35 dB (A). Inexpensive units with cheap components without noise insulation lie even at 55 – 70 dB (A), a background noise that makes communication almost impossible. Aftermarket products such as UV-C tubes (“lamps”) or filters should also be factored into the decision. HEPA filter units (with the highest performance H14) are available from 1,000 to 12,000 euros, depending on size.
UV-C air purifier - be careful not to be dazzled!
Compared to filter units, UV-C units are quieter. Air is also sucked in and led past UV-C lamps, while the disinfected air flows back into the room. The issues of air exchange rate and efficiency also hit home with these units. The UV lamps in the unit must be replaced and disposed of properly as they contain mercury. UV-C radiation can damage skin and eyes, so UV light must not be emitted into the room – either directly or diffusely.
Not all plasma is the same
In addition to centralized plasma recirculation units (which usually include units with ionization technology), there are decentralized plasma units, i.e. the air is enriched with cold atmospheric plasma. Plasma consists of ions, radicals and free electrons. This air-plasma mixture neutralizes viruses, bacteria and fungal spores immediately and constantly. The key to success is the right “mix” or composition of the plasma: Many processes produce too many ions and too few radicals, which are necessary for efficient disinfection.
Patented: Sterex plasma technology
Sterex plasma technology produces the species necessary for disinfecting air and surfaces, but not unwanted ones such as nitrogen radicals.
The Sterex development team worked closely on this with a plasma researcher who has been working on this topic for over 15 years. Another companion was Dr Ulrich Schmelz (Dipl.Ing. Dipl.Chem.) from the Competence Center for Technical Hygiene and Applied Microbiology in Malsfeld, who comprehensively tested Sterex for effectiveness and health. The lesson from this is clear: The Sterex process is unique, patented and an exclusive technology; it is also highly efficient and does not deposit ozone indoors.
A summer storm out of the box
The Cubusan air purifier uses Sterex plasma technology. The plasma-air mixture eliminates viruses and bacteria directly and throughout and very efficiently: namely 99.99% in the air and on surfaces. The unit is completely safe to use with respect to health: It creates a similar fresh air as that created after a summer thunderstorm or at a waterfall – in nature hydroxyl radicals are also generated by lightning and purify the atmosphere. The high-quality components make the Cubusan very quiet; it operates at 30-35 dB (A) depending on the unit type. No maintenance is required and no filters or lamps need to be changed. Therefore, no additional costs are incurred during operation. At just under 2,000 euros (for 50 m2), the Cubusan compares very favorably with other units with much better efficiency and performance.
Are we being "over-disinfected"?
Do not worry – the “good” bacteria on the body are not affected! The air-plasma mixture is much thinner than a solid object (air is 1000 times less dense) and cannot harm humans. Although plasma also disinfects surfaces, it does not render hands germ-free and, unlike disinfectants, it does not damage the microbiome.
