According to biological effects and ultraviolet rays, four bands are divided according to wavelength:
1. UVA band wavelength 320～400nm is also known as long-wave black spot effect. Ultraviolet has strong penetrating power. It penetrates most transparent glass and plastic. Sunlight contains long-wave ultraviolet rays. More than 98% can penetrate the ozone layer and clouds to reach the surface of the earth. UVA reaches the dermis layer of the skin. Destroy elastic fibers and collagen fibers. Our skin is tanned. 360nm wavelength UVA ultraviolet rays conform to the phototaxis response curve of insects. Making insect traps 300-420nm wavelength UVA ultraviolet rays pass through completely cut off the light. The special colored glass tube only radiates 365nm near ultraviolet light. Used in ore identification, stage decoration, currency checking and other places.
2. UVB band wavelength 275～320nm is also known as wave erythema effect. Ultraviolet rays and other shorter wavelengths will be absorbed by the transparent glass. Sunlight contains waves. Most of the ultraviolet rays are absorbed by the ozone layer. Only 2% can reach the surface of the earth. Special in summer and afternoon meetings. Strong UVB ultraviolet rays have an erythema effect on the human body. It can promote the metabolism of minerals and the formation of vitamin D in the body. Long-term or excessive exposure will cause the skin to tan and cause redness and peeling. ) And made of phosphor near 300nm peak.
3. The UVC band wavelength is 100～275nm, also known as short-wave sterilization. The ultraviolet penetrating ability is weak. It cannot penetrate most of transparent glass and plastic. Sunlight contains short-wave ultraviolet rays. It is almost completely absorbed by the ozone layer. Short-wave ultraviolet rays are harmful to the human body. High-intensity radiation can also cause skin cancer ultraviolet germicidal lamps to emit UVC short-wave ultraviolet rays.
4. The UVD band wavelength is less than 100nm, also called vacuum ultraviolet.
5. Principle of ultraviolet sterilization:
Ultraviolet sterilization destroys and changes the structure of microbial DNA (deoxyribonucleic acid) through ultraviolet radiation, so that the bacteria die immediately or can reproduce. It has a germicidal effect. UVC ultraviolet rays are easily absorbed by biological DNA due to C-band ultraviolet rays, especially around 253.7nm.
Ultraviolet sterilization is a purely physical disinfection method. It has the advantages of simple and convenient, broad-spectrum, high-efficiency, no secondary pollution, easy management and automation, etc. With the introduction of various new design ultraviolet lamps, the application range of ultraviolet sterilization has also been continuously expanded.
