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

UVA

Long-wave UVA, with a wavelength between 320-400 nanometers, is also called long-wave black spot effect ultraviolet rays. It has strong penetrating power, it can penetrate glass, even 9 feet of water; and it exists in all seasons of the year, regardless what the weather it is, and also day and night.

Damage to the human body: More than 95% of the ultraviolet rays exposed to the skin are UVA, so it is the most harmful to the skin. UVA can attack the dermis through the epidermis, causing serious damage to the collagen and elastin in the skin; and the dermal cells have poor self-protection ability, and a small amount of UVA can cause great damage. Over time and time, skin problems such as slack, wrinkles, and capillaries appear.

At the same time, it can activate tyrosinase, leading to instant melanin deposition and new melanin formation, making the skin darker and lacking luster. UVA can cause long-term, chronic and continuous damage and make the skin aging prematurely, so it is also called aging rays.

Application areas: UVA ultraviolet rays with a wavelength of 360nm conform to the phototaxis response curve of insects, and can be used to make insect trap lamps. UVA ultraviolet rays with wavelengths of 300-420nm can pass through a special colored glass tube that completely cuts off visible light, and only emit near-ultraviolet light centered at 365nm, which can be used for ore identification, stage decoration, currency verification and other places.

Medium wave UVB, with a wavelength between 275nm and 320nm, is also known as medium wave erythema effect ultraviolet rays. Medium penetration, its shorter wavelength part will be absorbed by the transparent glass, most of the medium-wave ultraviolet contained in sunlight is absorbed by the ozone layer, and only less than 2% can reach the surface of the earth, which is particularly strong in summer and afternoon.

Damage to the human body: it will oxidize the protective lipid layer of the epidermis and dry out the skin; further, it will deteriorate the nucleic acid and protein in the epidermal cells, causing symptoms such as acute dermatitis (ie sunburn), and the skin will turn red , Pain. In severe cases, such as prolonged exposure, it can easily lead to skin cancer. In addition, the long-term damage of UVB can also cause the mutation of melanocytes, resulted in sun spots that are difficult to eliminate.

Application areas: UV health care lamps and plant growth lamps are made of special transparent purple glass (not transmitting light below 254nm) and phosphors with a peak around 300nm.

UVC

Short-wave UVC, with a wavelength between 200 and 275 nanometers, is also called short-wave sterilizing ultraviolet. Its penetrating ability is the weakest, unable to penetrate most transparent glass and plastics. The short-wave ultraviolet rays contained in sunlight are almost completely absorbed by the ozone layer, and are absorbed by the ozone layer before reaching the ground.

Damage to human body: UVC in nature is absorbed by the ozone layer before it reaches the ground, and its impact on the skin is negligible, but in fact, short-wave ultraviolet rays are very harmful to the human body and cannot be directly exposed to the human body. If it is directly irradiated, short-term irradiation can burn the skin, and long-term or high-intensity irradiation can also cause skin cancer.

Application area: UVC short-wave ultraviolet light emitted by the ultraviolet germicidal lamp. Shortwave ultraviolet rays are widely used in hospitals, air conditioning systems, disinfection cabinets, water treatment equipment, drinking fountains, sewage treatment plants, swimming pools, food and beverage processing and packaging equipment, food factories, cosmetics factories, dairy products factories, brewery, beverage factories, bakeries and refrigeration areas.

Advantages and disadvantages of UV

Advantages of ultraviolet rays: 1) disinfection and sterilization; 2) helps to promote bone development; 3) good for blood color; 4) occasionally treat certain skin diseases; 5) promote mineral metabolism and the formation of vitamin D in the body.

Disadvantages of ultraviolet rays: 1) cause skin aging wrinkles; 2) skin spots; 3) skin dermatitis; 4) skin cancer.

Knowledge about UVC ultraviolet rays

Principle of UVC sterilization
Among the various wavelengths of ultraviolet light, only short-wave ultraviolet UVC has the effect of sterilization and disinfection. It is a pure physical disinfection method. It has the characteristics of broad-spectrum, high efficiency, rapid and thorough, no need to add chemicals, no drug resistance, and no secondary pollution.
UVD ultraviolet rays with a wavelength of 185nm can turn oxygen O2 in the air into ozone O3. Ozone has a strong oxidizing effect and can effectively kill bacteria, but ultraviolet rays with a wavelength of 185nm have no sterilization effect. The dispersibility of ozone can just make up for the shortcomings of ultraviolet rays: 1). can only spread in a straight line and disinfection has dead ends  2) it can reach any corner of the space with the air, making sterilization and disinfection more completely.
The principle of ultraviolet sterilization: UV irradiation of bacteria, viruses and other microorganisms destroys the molecular structure of DNA (deoxyribonucleic acid) or RNA (ribonucleic acid) in microbial cells, causing DNA strand breaks and cross-linking of nucleic acids and proteins, causing growth cell death and regenerative cell death to achieve the effect of sterilization. Ultraviolet rays with a wavelength of 253.7nm have the best sterilization effect.
Ozone sterilization principle: UVD ultraviolet rays with a wavelength of 185nm irradiate the air, which can decompose the oxygen O2 molecules in the air, and the generated O atoms combine with the O2 molecules to produce ozone O3. Ozone O3 has a strong oxidizing effect, which can destroy the cell wall of decomposing bacteria, penetrate into the cell and oxidize and decompose to destroy the polymerization of glucose oxidase, ribonucleic acid (RNA), deoxyribonucleic acid (DNA), protein, lipids, and polysaccharides. It can destroy the metabolism and reproduction process of bacteria and die, and achieve the effect of sterilization and disinfection.

High-efficiency sterilization: The sterilization effect of ultraviolet rays on bacteria and viruses is generally completed within a few seconds, almost instantaneously, and the sterilization and disinfection capacity is 600-3000 times greater than that of chlorine.

Broad-spectrum sterilization: UV technology has the highest broad-spectrum sterilization among all current sterilization technologies. It can kill almost all bacteria and viruses with high efficiency.

Sterilization more completely: the combined use of ultraviolet rays and ozone (UVC+O3) can exert a more powerful and thorough sterilization power. Ultraviolet rays irradiate the air and the surface of objects directly to achieve strong sterilization; ozone penetrates into all corners of the room with the air to kill indoor bacteria completely.

UVC sterilization efficiency

UVC ultraviolet bactericidal efficiency against common bacteria and viruses (radiation intensity: 30000μW/cm2)