# Influence of disinfection efficiency and air flow through the disinfection unit on reducing the risk of infection transmission

There are a large number of models simulating the course of the spread of diseases in various areas and under different conditions – there are one or more infected people in the room emitting viruses over a long period by having fun or singing, etc. To demonstrate the effect of disinfection efficien-cy of the device at a given air flow to reduce the risk of infection transmis-sion, we chose a simple model. The general conclusions resulting from this simulation for the selection of the most suitable disinfectant air purifier also apply to all more complex models and, above all, to actual conditions.

However, it should be emphasised that these conclusions apply only to disinfection units that have a certified disinfection efficiency and, at the same time, ensure air flow throughout the room. There are a number of disinfection units that have poorly designed airflow surrounding these units and fail to ensure that all the air in the room regularly passes through the disinfection unit.

Suppose we have a room with a volume of 100 m^{3} (6m x 5m x 3.3m). Infect-ed people lived in this room and subsequently left. So there are no longer any infected people in the room, but there are 1 million viruses remaining in the area. The risk of transmitting infection depends, of course, on the type of virus and also on the minimum number of viruses that a person might inhale in order to become infected. Here we will assume that if the number of viruses in the room drops below 1-10, the room is not harmful to health and there is no risk of transmission of the infection.

The following table shows how the numbers of viruses decrease over time depending on the disinfection efficiency of the device. This decrease also depends upon the air flow through the disinfection unit. It therefore depends on how many times total air in the room has passed through the disinfection unit.

Therefore, if we place a disinfection unit with an efficiency of 90% in a room with a volume of 100 m^{3}, then 360 minutes at an air flow of 100 m^{3} / h through the unit are required to disinfect the room. If the disinfection unit has an efficiency of 90% at a flow rate of 200 m^{3} / h, the room will be disinfected in 180 minutes, while at a flow rate of 400 m^{3} / h there will be no risk of transmission in 90 minutes and at a flow rate of 600 m^{3} / h the room will be safe in 60 minutes.

If a disinfection unit with an efficiency of at least 99.999% is installed, as is the case with TriUV^{®}, the achievement of a healthy environment is radically shortened. If we install a unit with an efficiency of 99.999% at an air flow of 100 m^{3} / h, then we will achieve a healthy environment in 60 minutes. If the TriUV^{®} 600 unit is installed with a flow rate of 600 m^{3} / h, we will achieve a healthy environment in just 10 minutes.

The general recommendation for the minimum number of passages of all air in the room through the TriUV^{® }disinfection unit is as follows:

• At home – passage 4 times / hour

• Office, kindergartens, schools, hospitals, surgeries, dentists, veterinarians – 5 times / hour

• Operating rooms – 6 times / hour

Only simple models have been shown above to illustrate how important it is to choose disinfection units with the highest certified disinfection efficien-cy and the highest possible air flow through the unit. From a health point of view, they should produce the minimum possible noise. This conclusion is valid regardless of the model selected. There are a large number of far more complicated models of infection transmission, but these models can easily be misused to create the impression of high efficiency even with an average effective disinfection unit. As already mentioned, the most important information about the effectiveness of the unit is its disinfection efficiency in a single pass.