UVA、UVB、UVC And UVD

Fluorescent lamps, also known as fluorescent tubes or tube lights, are lighting devices that utilize low-pressure mercury vapor discharge. They consist of a long, narrow glass tube with a fluorescent powder coating on the inner wall. The tube contains a small amount of mercury vapor and an inert gas, such as argon or krypton.

When an electric current is applied to the tube, the current excites the mercury atoms, causing them to emit ultraviolet (UV) light. This UV light then interacts with the fluorescent powder coating, causing it to fluoresce and emit visible light. The fluorescent powder coating is responsible for converting the UV light into different colors, allowing fluorescent lamps to produce a variety of light colors, including warm white, cool white, and daylight.

To operate a fluorescent lamp, a ballast is required. A ballast is a device that regulates the current flowing to the lamp. There are two common types of ballasts used with fluorescent lamps: electronic ballasts and inductive ballasts. Electronic ballasts are more energy-efficient and provide better control over the lamp's operation, while inductive ballasts are older technology and less efficient.

Fluorescent lamps are more energy-efficient, typically consuming 25-35% less energy to produce the same amount of light. This energy efficiency translates into lower electricity costs. In addition, fluorescent lamps have a longer lifespan compared to incandescent bulbs, typically lasting 10.000 to 20.000 hours.

However, fluorescent lamps require a short warm-up time before reaching full brightness, and they may flicker or produce a buzzing sound during operation. The mercury in fluorescent lamps is also an environmental concern, as mercury is a hazardous substance that requires proper disposal.

Long-wave Ultraviolet Radiation (UVA)

The "A" in UVA stands for "Aging," meaning skin aging. UVA wavelengths range from 320 to 400 nm, also known as long-wave black spot effect ultraviolet radiation. It has strong penetrating power, able to penetrate glass and even 9 feet of water; and it is present year-round, regardless of weather or time of day. ​​Effects on the human body: More than 95% of the ultraviolet radiation that the skin is exposed to daily is UVA, therefore it causes the most damage to the skin. UVA can penetrate the epidermis and attack the dermis, damaging collagen and elastin in the skin; because dermal cells have poor self-protection capabilities, even small amounts of UVA can cause significant damage. At the same time, it can activate tyrosinase, forming melanin, causing the skin to darken and lose its luster. UVA causes long-term, chronic, and persistent damage, leading to premature skin aging, so it is also called aging/tanning radiation. Skin pigmentation (tanning) caused by ultraviolet radiation is divided into three stages: immediate tanning (IPD), persistent tanning (PPD), and delayed tanning (DT). IPD, PPD, and DT are all related to UVA, while UVB is only related to DT. IPD is an immediate reaction to exposure to low doses of UVA, appearing immediately after exposure and subsiding within 20 minutes to 2 hours. At higher UVA doses, PPD occurs and lasts for 2-24 hours. Both IPD and PPD are unrelated to the production of new melanin, but are caused by oxidation and redistribution of existing melanin. Delayed tanning (DT) occurs several days after exposure and is related to the synthesis of new melanin and the activity and proliferation of melanocytes. Both UVB and UVA can induce DT, but UVA-induced DT is preceded by IPD and PPD, and there is no significant redness of the skin. UVB-induced DT always involves erythema, and the efficiency of UVB in inducing DT is 2-3 orders of magnitude higher than that of UVA.

Medium-wave Ultraviolet Radiation (UVB band)

The "B" in UVB stands for "Burning," meaning burning. UVB wavelengths range from 280 to 320 nm, also known as medium-wave erythema effect ultraviolet radiation. Medium penetration, its shorter wavelengths are absorbed by transparent glass. Most of the medium-wave ultraviolet radiation in sunlight is absorbed by the ozone layer, with less than 2% reaching the Earth's surface. It is particularly strong in summer and in the afternoon. UVB ultraviolet radiation has an erythema effect on the human body, promoting mineral metabolism and vitamin D formation, but prolonged or excessive exposure can cause skin tanning, redness, and peeling, so it is also known as sunburn radiation. Erythema caused by UVB begins to appear about four hours after exposure, peaks at 8-24 hours, and subsides in about a day, but in fair-skinned (Caucasian) and older people, UVB-induced erythema may last for several weeks or even persist.

Short-wave ultraviolet radiation (UVC band) The "C" in UVC stands for "Cancerous," meaning carcinogenic. UVC wavelengths range from 100 to 280 nm, also known as short-wave germicidal ultraviolet radiation. It has weak penetration ability and cannot penetrate most transparent glass and plastics, but it has the highest energy. The short-wave ultraviolet radiation in sunlight is almost completely absorbed by the ozone layer before reaching the ground. Effects on the human body: Because UVC in nature is absorbed by the ozone layer before reaching the ground, its impact on the skin is negligible. However, short-wave ultraviolet radiation is actually very harmful to the human body and should not be directly exposed to the body. If directly exposed, it can burn the skin in a short time, and long-term or high-intensity exposure can cause skin cancer. This is because it can damage DNA and increase the risk of skin cancer. This is why UVC is sometimes called "carcinogenic ultraviolet radiation." Application areas: Ultraviolet germicidal lamps emit UVC short-wave ultraviolet radiation. Short-wave ultraviolet radiation is widely used in hospitals, air conditioning systems, disinfection cabinets, water treatment equipment, water dispensers, sewage treatment plants, swimming pools, food and beverage processing and packaging equipment, food factories, cosmetics factories, dairy factories, breweries, beverage factories, bakeries, and cold storage facilities.

Advantages of UVC Sterilization

High-Efficiency Sterilization: The sterilization effect of ultraviolet light on bacteria and viruses is generally completed within a few seconds, almost instantaneously. Its sterilization and disinfection capabilities are 600 to 3000 times greater than chlorine.

Broad-Spectrum Sterilization: Among all current disinfection technologies, ultraviolet technology has the broadest spectrum of sterilization. It can efficiently kill almost all bacteria and viruses.

More Thorough Sterilization: The combination of ultraviolet light and ozone (UV-C + O3) can exert a more powerful and thorough sterilization and disinfection effect. Ultraviolet light directly irradiates the air and object surfaces for powerful sterilization and disinfection; ozone penetrates into all corners of the room with the air, thoroughly killing indoor bacteria.

Completely Environmentally Friendly: Sterilization and disinfection are achieved by ultraviolet light emitted from a UV lamp. The ultraviolet light irradiates oxygen in the air to generate ozone, which then uses strong oxidation to kill bacteria and viruses. The entire sterilization process does not require the addition of any chemical agents, truly achieving complete environmental protection.

No Drug Resistance: Both ultraviolet light and ozone directly destroy the DNA, RNA, and proteins in bacterial and viral cells, causing the cells to die directly and preventing reproduction and replication.  Therefore, there is no drug resistance. Other chemical disinfectants can cause bacteria and viruses to develop drug resistance, rendering the chemical disinfectant ineffective.

No Secondary Pollution: Ultraviolet light and ozone cause bacteria and viruses to die directly, without producing any other chemical pollutants; at the same time, ozone converts into oxygen at room temperature within 15-30 minutes (ozone half-life), resulting in no residual secondary pollution.

UVC ultraviolet light has high sterilization efficiency against common bacteria and viruses (radiation intensity: 30000 μW/cm²).

Short-Wave Ultraviolet (UVD Band)

The UVD band, with a wavelength of 100-200 nm, is also known as vacuum ultraviolet. It has extremely weak penetration ability. It can oxidize oxygen in the air into ozone, and is called the ozone generation line. Oxygen (O2) in the air undergoes photolysis under ultraviolet light irradiation, producing ozone (O3). Ozone is an effective oxidizing agent that can kill bacteria and viruses in water or air, and can be used for vegetable cleaning and air disinfection.

In conclusion, ultraviolet radiation, encompassing UVA, UVB, UVC, and UVD bands, presents a complex array of effects and applications. While UVA and UVB impact human skin in various ways, from aging to sunburn, UVC stands out for its potent sterilization capabilities, widely utilized in diverse settings to ensure hygiene and safety. UVD, though less penetrative, contributes to ozone generation, further enhancing disinfection processes. Understanding these distinct characteristics of ultraviolet bands enables us to harness their benefits effectively while mitigating potential risks, promoting a healthier and safer environment for all.