It should be noted that high-quality ventilation of a room with a high multiplicity and without drafts is not so natural to organize in the summer.
It is based on the preceding that local recirculating systems are often used to disinfect indoor air. They are with much less energy and perform the role of the very ventilation.
The most widespread are bactericidal ultraviolet recirculatory – devices that disinfect sterile aire and air passing through them with ultraviolet radiation. The composition of such UV-recirculatory includes one or more bactericidal lamps (sometimes they are also called quartz lamps).
When choosing a UV recirculatory, like any other, you need to remember a few fundamental points:
- The hourly capacity (m 3 / h) of the recirculatory or group of recirculatory should be 4-5 times the volume of the room in which they will be used. Otherwise, it is a waste of money.
- There are two types of UV recirculatory:
- some provide a small UV dose inside the device (7-10 mJ / cm 2 ) and are suitable for the prevention, for example, of flu and other forms unstable to UV radiation,
- , and others, special ones, provide an increased UV dose (25–30 mg/cm 2 ) and are used for deeper air disinfection over a broader range of microorganisms
- If your recirculatory glows blue in the dark, it is advisable to stay away from it, especially not allowing children to look into it (UV radiation is hazardous for the eyes).
A reasonably simple differential equation describes the dependence of the concentration of viruses in indoor air, the solution given both in our  and in foreign literature . We will not provide this equation, but consider four cases and present the dependence of the concentration of microorganisms in the room for each of them graphically.