Air filter is an important element of any ventilation system. It is responsible, among other things, for the quality of air fed to the place where we spend most of our lives. This is why it is important to replace it when it comes to dirt. This is an operational element and is periodically replaced. For dirt on many devices, we inform you of the message on the display or the indicator light. In cases where our control unit does not have such facilities, it can be easily determined by the loudest operation of the fans and the visual inspection of the filter. The dirty filter is black and covered with a layer of pollen. The most commonly used filters with the G4 filtration class are mainly used to protect the sensitive components of the plant and to filter out soother, squeak, insect, leaf, mist, which could damage it. In the air that we breathe there are also much worse particles of the PM10 group, which can settle in our airways and penetrate into the bloodstream causing diseases, allergies, induce inflammation, asthma, throat tumors, larynx and lungs. We can reduce the level of these molecules in the surrounding air by applying filters accurate to the filtration classes M5, F7, F9 from which the filtration class F9 is the most effective. Applying filters with higher filtration efficiency reduces the risk of these diseases and will make you feel better in your environment. Applying a higher class of filtration will not adversely affect the device only may gently shorten the filter change period. What we should use the filtration class is influenced by the environment, the time of year of the plant dust. The most severe for our lungs is the heating season, it is known that then it is worth to use a higher class of filtration and during the summer season we can afford a lower. The same is true for the dusting of plants and the inhabing of a heavily urbanised area.