The use of ultraviolet radiation for air disinfection

The composition of solar radiation reaching the Earth’s surface includes 59% infrared radiation, 40% visible and 1% ultraviolet. Schematically, the spectral composition of sunlight is presented.

The radiant energy of the Sun and, in particular, its most biologically active region – ultraviolet radiation, is a constantly acting environmental factor that largely determines the processes of natural self-purification of atmospheric air, natural water, and soil.

By the nature of the biological action, the ultraviolet part of the solar spectrum is conventionally divided into three areas – A, B, C.

The long-wavelength region A (400–320 nm) has a weak general stimulating, mainly erythemal and pigment-forming (tanning) effect.

The medium- wave region B (320–280 nm) has a strong general stimulating and vitamin-forming (antirachitic) effect. In the surface layers of the skin, cholecalciferol, vitamin D3, is formed from the 7.8-dehydrocholesterol contained in the germ layer of the epidermis.

The short- wavelength region C (280–200 nm) has a predominantly bactericidal effect due to disruption of the vital functions of microbial cells and the breakdown of their nucleic components. Vegetative forms of microorganisms and viruses die in direct sunlight within 10-15 minutes, spore forms in 40-60 minutes.

As noted above, the control of indoor air dust is of great practical importance for the prevention of aerogenic infections and allergic conditions. The destruction of microbes directly in the phase of liquid bacterial aerosol is most effective. At present, physical and chemical methods of air sanitation in rooms have been developed that are quite effective and available for widespread use. Among them, one of the first places is disinfection of air with ultraviolet rays.

Created artificial sources of ultraviolet radiation region C – Discharge bactericidal and Mercury quartz lamps. Regular glass, due to titanium and iron impurities, retains up to 80–90% of ultraviolet radiation, therefore, BEC bactericidal lamps are made of uviol (quartz) glass, purified of these impurities and transmitting most of the ultraviolet radiation. The lamps are filled with argon with a metered amount of mercury at low pressure. The maximum emission of BUV lamps at a wavelength of 254 nm provides the greatest bactericidal effect of radiant energy. The industry produces lamps with a power of 15 W (BUV-15), 30 W (BUV-30), 60 W (BUV-60) and 30 W with an increased current density (BUV-30 P).

BUV lamps are used only for disinfection of environmental objects: air, water, various items (dishes, toys). Dosing of radiation of BUV lamps should be carried out especially carefully, since short-wave ultraviolet radiation has significant abiotic

by action. Irradiation of people with direct rays from these lamps is not allowed, since burns to the mucous membrane of the eyes can occur – photophthalmia, adverse changes in the composition of the blood, etc.

For BUV lamps, special screens have been developed that direct the rays so that the lamp is not visible to a standing person. For the installation of these lamps, there are wall, ceiling, and mobile fixtures (OBN-160 irradiators; OBP-300; OBP-450), as well as combined illuminators designed for illuminating fluorescent lamps and BUV lamps.

event_note August 12, 2019

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