Basic principles of UV-C irradiation

UV-C irradiation is a highly effective method of removing viruses from our environment. The technology of UV irradiation has been known for approximately one hundred years and is mainly used in medicine and food production. The onset of the coronavirus pandemic has now broadened the scope of application.
UV-C lamps are one of the most effective devices for the elimination of bacteria, viruses and fungi.

Cell structure before UVC irradiation

Cell structure after UVC irradiation

Exposing microorganisms to UVC radiation inactivates their DNA and RNA. Irradiation with UVC light has become an effective, convenient, affordable and environmentally friendly form of decontamination. UVC disinfection requires no human labour and consumes no chemical agents. Consequently, it is cost-efficient and ecologically sound.
It also minimises the consumption of chemical disinfectants.

Frequently asked questions: UV-C air disinfection

What are the advantages of UV-C air disinfection?
In contrast to air purification units based on chemicals or the use of filters, UVC air disinfection requires very little maintenance, as our system requires no chemicals, nor does it have filters that need to be changed. The maintenance interval of the UV-Cero 300 system is solely determined by the UV lamps, and assuming normal use, these only need to be changed after the third year of operation.

Is it possible to combat coronavirus by disinfecting the air we breathe with UV-C?
Yes. The UV-C output of our UV-C disinfection unit is more than twice the required LD90 output for SARS-CoV-2 viruses. LD90 refers to the UV-C output required to kill 90% of the viruses.
Our units achieve a proven disinfection rate of 99.9% for extracted air.

What is the survival rate of viruses extracted by our UV-C disinfection chamber?
In the disinfection chamber of our UV-Cero 300 system, 99.9% of all viruses (SARS, influenza and others) directed past the UV-C tubes are neutralised immediately and permanently. This high level of performance is achieved because the extracted air is retained in the disinfection chamber for approximately two seconds. Just under two seconds is the length of time that is necessary to achieve our neutralisation rate of 99.9%. All of the relevant data has been published in a test report, which was prepared after extensive testing of our UV-Cero 300 system. Conventional filter systems do not kill or neutralise viruses; instead, the viruses are trapped, which means that, when the filters are changed, any active germs or viruses still present may escape back into the surrounding air, thereby posing a risk to the person changing the filters.

Do aerosols circulate when a UV-C disinfection system is in use?
Our UV-Cero units are installed where the aerosols are created, i.e. high up in the room above where people congregate, so that the aerosols are drawn upwards and disinfected. If a space exceeds 50 square metres, we recommend a second unit to decrease the distance the air has to travel before being disinfected and thus reduce the circulation of virus-laden aerosols.

What are the running costs of a UV-C air purification system?
Air disinfection using UVC light does not generate any waste materials apart from the UVC lamps which have to be disposed of responsibly at the nearest collection point for electrical waste when they reach the end of their service life. The control LEDs on all UV-Cero models indicate the continued correct functioning of the UVC lamps. A UVC tube has a service life of 9,000 hours. This delivers approximately four years of operation assuming normal office hours. In the case of filter systems, the contaminated filters must be replaced or cleaned regularly and, in some cases, disposed of as hazardous waste. They present the risk that people can come into contact with contaminated material at any time. The manufacturers make recommendations as to when the filters must be replaced, but these are only general guidelines. The actual virus load in the filter is not measured. As a result, filters are likely to be replaced either too early (which leads to a waste of resources and high operating costs over many years of use) or too late, which means that germs and viruses can no longer be filtered properly and, in the worst case, are released back into the room, thereby actually increasing rather than minimising the health risk.

What sort of indoor spaces are UV-C air purifiers suitable for, and how many units should I install?
Our UV-Cero 300 processes approximately 150m³/h on its quietest setting (= 50% output). A room with an area of 60 square metres and a height of 2.50 metres contains 150 m³ air volume.
One of our units would need about one hour to completely disinfect the air in the room. If you turn up the power, it will go faster, but the unit will be more audible.

We recommend installing two units for a room area of more than 50 square metres because:
a) a room of that size holds more people;
b) the air volume will be disinfected in a shorter time at a lower noise level.
If in doubt, ask us to recommend the optimum setup for your circumstances.

What is the best location in the room for an air purifier unit?
If an air disinfection system is positioned at floor level, it cannot do its job properly. Heavier particles or droplets that are emitted when a person coughs or sneezes fall to the floor. Because they are moist, they stick to the carpet or floorboards from where they can no longer be removed by air extraction alone. Floor-mounted vacuum units mainly suck up dust and dry particles. They are ineffective against aerosols, because these are suspended in the air.

With our system, we concentrate on the aerosols that remain in the air.

For this reason, our UV-Cero units are designed to be mounted on the ceiling or on the wall at ceiling height.
The harmful aerosols are to be found floating around in the air and are not on the floor...

Do I have to switch the UV-C air purifiers on and off manually?
This depends on the product. The current version of the UV-Cero 300 is operated by means of its on/off switch.

Where are UV-C air purifiers used?
Einsatzmöglichkeiten ergeben sich insbesondere in geschlossenen Bereichen, in denen mehrere Personen zusammenkommen. Da im mitteleuropäischen Klima eine dauerhafte und umfassende Zufuhr von Frischluft oftmals witterungsbedingt nicht möglich ist, erhöht sich automatisch die Belastung der Luft mit keimbehafteten Aerosolen.
Unsere Luft-Desinfektionsanlagen reduzieren in diesen Situationen die Keimbelastung in der Luft nachweislich und helfen, den Schwellwert für Infektionen dauerhaft zu unterschreiten.

Where should air purifier systems be mounted?
Our UV-Cero 300 should be mounted on the ceiling or on the wall at ceiling height. Aerosols are usually suspended at a height of 1.50 metres and above.
In any case, it is easier to run a power cable higher up.

Who should I ask to install an air disinfection system?
Installing our system is a job for a professional. Installation instructions are included in the package.

Are air purifiers injurious to health?
UV-C radiation can cause damage to the skin and eyes if not used properly. As the manufacturer of the UV-Cero systems, we have enclosed our UV-C disinfection chamber in its own metal housing to ensure that no UV-C radiation escapes. We have the relevant test report to prove that our product does not present any health hazard. If the UV-C disinfection chamber were to be opened during operation, a cut-out fuse immediately interrupts the power supply. UV-C disinfection has been used successfully in a variety of settings for many years now, for example in hospitals.

Do you offer personal advice on these devices?
It is very important to us that you understand our products. We will be happy to advise you on the individual products by telephone or e-mail.
We have also explained everything you need to know here on our product website.

Expert opinions on UV-C air disinfection

Here you can read official information compiled by government experts on the use of UVC light for air disinfection.

German Federal Office for Radiation Protection
Disinfection systems or procedures in which people are safely protected from UV radiation present no risk. These include systems where the UV-C source is installed in an enclosed unit or where shielding of the source ensures that persons present are not exposed to UV-C radiation.

German Federal Environment Agency
UVC irradiation of indoor air reduces viral load, because it is an effective method of killing bacteria and inactivating viruses. Devices with UVC radiation sources have long been used for surface disinfection in a variety of settings, for example in laboratories.

Choosing the right UV-C air disinfection system

Since the onset of the coronavirus pandemic, a lot of products have come onto the market promising various forms of air disinfection, including the use of UV-C light. It is sometimes hard to distinguish between offers that are just playing on the fears of the general public and those that are genuine. We have taken a close look at the products advertised by our competitors, scrutinising the data sheets and testing some of them in our development laboratory. We identified the following criteria which you may find helpful in choosing the right UV-C air disinfection system for your circumstances:

Key criteria in selecting the right UV-C disinfection solution
A large number of research studies have established that viruses, bacteria and fungal spores (germs) can be killed by UVC light. When evaluating the results of these research projects, it should be noted that there is a difference between surface disinfection and air purification. In the case of surface disinfection, large dimensions (sometimes > 1 m) and long exposure times apply, whereas in the case of air purification, smaller dimensions (approximately 2 cm) apply to allow a significant reduction in exposure time. Nevertheless, a defined dose of UVC light (mJ/cm²) is needed to achieve an LD value of 90 (LD90 signifies that 90% of a particular virus has been deactivated).
Some of our competitors’ products are advertised with performance specifications that are either far too low (no disinfection effect) or even technically unfeasible (UVC performance is limited by the lamps and LEDs that are currently available).

Furthermore, we are not aware of any other product that has a dwell time in the disinfection chamber for the extracted air (aerosols) of just under two seconds, the time that is required to neutralise the viruses and which is achieved by UV-Cero 300.
This dwell time together with the special UVC tubes in our system enables us to easily achieve the disinfection factor that is necessary for the elimination of viruses.

Laboratory tests
Certain providers claim a ‘laboratory-confirmed’ deactivation of coronaviruses of up to 99.9999%. This value cannot be achieved in a normal environment; it implies an absolutely sterile room, which is not possible in any space frequented by people.
Often, the other performance specifications of the device are inconsistent with the level of protection claimed, either because the UVC output is too low or because the specification does not refer to a single pass of air, but instead to a 24-hour test conducted in a small closed room – an unrealistic application scenario. Moreover, there is no mention of a dwell time for the extracted air in the irradiation chamber. Be sure to question the laboratory results and technical specifications here!

Technical status
Some products advertised are simply not feasible in price terms with the components currently available. Special care should be taken with offers based on LED solutions. UVC LEDs are still very expensive and have only a very limited service life and low efficiency. Often, only UVA or UVB LEDs are installed, which are useless for disinfection purposes. In general, you should check whether the specified volume flow (i.e. the rate at which air is circulated) matches up with the UVC output of the lamp.
-> Look at the output of the UVC component of the lamp rather than the power consumption in watts.

Our UV-Cero 300 disinfection system with an air flow rate of 150m³/h (= 50% output) and a UVC light output of just under 30W (4 x 7.3W) clearly exceeds the specification required to neutralise viruses. Even when the UV-Cero 300 is set at maximum output of 300m³/h (= 100% power), the deactivation rate is still approximately 99%.

Areas of application for UV-C technology

Our UV-Cero 300 can be used in the following locations without any problems:

  • Medical practices
  • Meeting rooms
  • Waiting rooms
  • Schools
  • Hospitals
  • Nursing homes
  • Offices
  • Fitness studios
  • Reception foyers
  • Retail premises
  • and many more besides...