The World Health Organization has recently become interested in indoor air quality and came up with disappointing results. The reason for the special attention to air quality is due to the fact that the sanitary and hygienic conditions for the operation of buildings are severely violated, namely the appearance of dampness and mold on the windows and the growth of diseases such as asthma. In residential areas, air quality depends on the natural ventilation system. The fresh image enters through the open window, through the cracks, mixes with the dirty and is released through the exhaust ducts of the kitchen or toilet. Only in this system, too, there are shortcomings. If it's poorly designed, then all the upstairs neighbors will know what you're cooking.
But the big problem lies elsewhere. If houses are designed with plastic windows or airtight doors, then air does not penetrate there at all. This is good, in that cases, that the heat is stored in the house, and does not drain into the street. On the other hand, these structures reduce the natural exchange of air, and this leads to a high content of harmful substances in the air.
To prevent this from happening, residents of houses need to do frequent ventilation of their apartments or install wall supply valves. Such valves are mounted on the bearing walls of the building. These valves perfectly ventilate the apartment, while they have high noise and heat insulation. also in such cases, central air conditioning systems can be of great help. But, today they cost a lot of money and the residents of the houses put separate air conditioners in the apartments.