Ultraviolet light is usually divided into four bands:
1, UVA band, wavelength 320 ~ 400nm, also known as long wave black spot effect ultraviolet.
It has a strong penetrating power, can penetrate most transparent glass and plastic. More than 98% of the UVA contained in sunlight can penetrate the ozone layer and clouds to reach the Earth’s surface. Uva can reach the dermis of the skin, destroying elastic fibers and collagen fibers, and giving our skin a tan. UVA ultraviolet light at 360nm wavelength is in line with the phototaxis response curve of insects, and can be used to produce insect traps. UVA ultraviolet light of 300-420nm wavelength can only radiate near ultraviolet light centered on 365nm through special colored glass lamps that completely cut off visible light, which can be used for ore identification, stage decoration, banknote inspection and other places. In October 2009, German and Italian scientists found that “astaxanthin” can effectively eliminate “ultraviolet UVA” damage to skin cells.
2, UVB band, wavelength 275 ~ 320nm, also known as the middle wave erythema effect of ultraviolet.
Medium penetration, its short wavelength part will be absorbed by the transparent glass, sunlight contains UVB is mostly absorbed by the ozone layer, only less than 2% can reach the Earth’s surface, in the summer and afternoon will be particularly strong. UVB ultraviolet light has a erythema effect on the human body, which can promote mineral metabolism and vitamin D formation in the body, but long-term or excessive exposure will make the skin tanned and cause red swelling and peeling. Ultraviolet health lamps and plant growth lamps are made of special violet glass (not through light below 254nm) and phosphors with peaks near 300nm.
3, UVC band, wavelength 200 ~ 275nm, also known as short-wave sterilization ultraviolet.
It has the weakest penetration ability and cannot penetrate most transparent glass and plastic. Sunlight contains shortwave ultraviolet rays that are almost completely absorbed by the ozone layer. Shortwave ultraviolet radiation is very harmful to the human body, short exposure can burn the skin, long-term or high intensity exposure can also cause skin cancer. Ultraviolet germicidal lamps emit UVC short-wave ultraviolet light.
4, UVD band, wavelength 100 ~ 200nm, also known as vacuum ultraviolet.

Its penetration is extremely weak. It can convert oxygen in the air into ozone, called ozone generation line.