[Science] UVA, UVB, UVC, UVD distinction and application areas

UV wavelength classification and Application

According to the different biological effects, according to the wavelength of ultraviolet light is divided into four bands: long wave UVA, medium wave UVB, short wave UVC, vacuum wave UVD. The longer the wavelength, the stronger penetration ability.

UVA

Long wavelength UVA, wavelength range from 320 to 400 nm, also known as the long wavelength dark spot effect ultraviolet. Has a strong penetration, can penetrate the glass, even 9 feet of water; and the seasons of the year, regardless of Yinqing, there are.

The degree of damage to the human body: more than 95% of the daily skin exposure to ultraviolet radiation is UVA, so it's the greatest damage to the skin. UVA can attack the dermis through the skin, so that the skin collagen and elastin have been hit hard; and dermal cells self-protection ability is poor, a small amount of UVA can cause great harm. Over time, the skin produces relaxation, wrinkles, microvascular problems.

At the same time, it can activate tyrosinase, resulting in immediate melanin deposition and new melanin formation, so that the skin black, lack of luster. UVA can cause chronic, chronic and lasting damage, so that the skin prematurely aging, also known as aging ray.

Application: UVA 360nm UV wavelength response curve with phototaxis of insects, can produce light. UVA UV wavelength of 300-420nm can be completely through the special colored glass lamp by visible light, near ultraviolet radiation only with 365nm as the center, can be used for ore identification, stage decoration, lighting and other places.

UVB

Medium wave UVB, the wavelength range from 275 to 320 nm, also known as the effect of UVB erythema. The medium penetration, the shorter wavelength will be transparent glass absorption, sunlight contains ultraviolet mostly absorbed by the ozone layer, only less than 2% can reach the surface of the earth, and will be particularly strong in the summer afternoon.

The degree of damage on the human body: it will make the surface oxidation of lipid layer leather protective effect, make the skin become dry; further the nucleic acid and protein denaturation in epidermal cells, produce acute dermatitis (i.e. sunburn) and other symptoms, the skin becomes red and sore. Serious, such as prolonged exposure, but also easily lead to skin cancer. In addition, UVB's long-term damage can also cause changes in melanocytes, resulting in difficult to eliminate the sun spots.

Application areas: UV lamp, plant growth lamp is issued by the use of special transparent glass (not less than 254nm light) and the peak in the vicinity of 300nm phosphor.

UVC

Short wave UVC, wavelength range from 200 to 275 nm, also known as short wave ultraviolet sterilization. Its penetration ability is the weakest, unable to penetrate most transparent glass and plastic. The sun's ultraviolet rays, which are absorbed by the ozone layer, are absorbed by the ozone layer before reaching the ground.

The degree of damage on the human body: the nature of the UVC because of not reaching the ground is absorbed by the ozone layer, the skin effect can be neglected, but short wave UV damage on the human body is very large, can not directly irradiate the human body. If direct irradiation, a short time irradiation can burn the skin, long-term or high-intensity radiation will cause skin cancer.

Application areas: ultraviolet germicidal lamp is issued by UVC short wave ultraviolet. Short wave ultraviolet light is widely used in hospitals, air conditioning system, disinfection cabinet, water dispenser, water treatment equipment, sewage treatment plant, swimming pool, food and beverage processing and packaging equipment, food factory, cosmetics factory, dairy factory, brewery, beverage factory, bakery and freezer etc..

Advantages and disadvantages of UV

UV advantages: 1) disinfection and sterilization; 2) to promote bone development; 3) beneficial to the blood; 4) occasionally treat certain skin diseases; 5) can promote the formation of mineral metabolism and vitamin D.

UV defects: 1) to make the skin aging wrinkles; 2) produce spots; 3) cause dermatitis; skin cancer caused by 4.

About UVC UV knowledge

Sterilization principle of UVC

The wavelength of ultraviolet ray, ultraviolet UVC only has the function of disinfection and sterilization, belongs to the pure physical disinfection method, with broad-spectrum, rapid and complete, without the addition of chemical agents, there is no resistance, no two pollution etc..

185nm wavelength of UVD UV can be the oxygen in the air O2 into ozone O3, ozone has strong oxidation, can effectively kill bacteria, but the wavelength of 185nm ultraviolet itself does not have the role of sterilization. The diffusion of ozone can make up for the fact that the ultraviolet ray can only be transmitted in straight line, and the disinfection has the disadvantages of the dead angle.

Ultraviolet sterilization principle: through the ultraviolet irradiation of bacteria, viruses and other microorganisms, destruction of body cells in DNA (deoxyribonucleic acid) or RNA (ribonucleic acid) molecular structure caused by crosslinking of DNA strand breaks, nucleic acid and protein breakdown, cause of death and regeneration of cell death of cell growth, achieve sterilization the effect of. Among them, the effect of UV disinfection with wavelength 253.7nm is the best.

Ozone sterilization principle: the wavelength of UVD 185nm ultraviolet light air, can break down the oxygen in the air O2 molecules, the generated O atoms and then combine with O2 molecules to produce ozone O3. O3 has a strong oxidation of ozone, can destroy the cell wall degrading bacteria, through intracellular oxidative destruction of glucose oxidase, ribonucleic acid (RNA) and deoxyribonucleic acid (DNA), protein, lipids, polysaccharides