Li Jinmin, Director of the State Key Laboratory of Joint Innovation in Semiconductor Lighting;
Yan Jianchang, Researcher, Institute of Semiconductors, Chinese Academy of Sciences;
Wang Di, Engineer, Health Appliance Testing Center, China Household Appliance Research Institute.
In addition to the usual masks, alcohol and goggles, ultraviolet germicidal lamps are also an effective prevention material to fight the new coronary pneumonia outbreak. The Protocol for the Diagnosis and Treatment of Pneumonia with Novel Coronavirus Infections (Fifth Trial Edition) states that novel coronaviruses are sensitive to ultraviolet light.
The far ultraviolet disinfection effect is the strongest
Germicidal UV disinfection is an old and well established method. A quilt under the sun is the most primitive way to remove mites and sterilize them with UV light.
Semiconductor Lighting Joint Innovation State Key Laboratory Director Li Jinmin said that the principle of ultraviolet disinfection is the use of high-energy ultraviolet light to break the DNA double helix chain, so as to achieve the inactivation of bacteria and viruses. To achieve effective sterilization and disinfection of ultraviolet light needs to meet certain requirements, pay attention to the wavelength of the ultraviolet light source, irradiation dose and time, that is, it must be the deep ultraviolet light of the UVC wavelength below 280nm, for different bacteria and viruses to meet a certain irradiation dose and time, otherwise cannot be inactivated.
According to the Chinese Academy of Sciences Semiconductor Research Institute Yan Jianchang, according to the wavelength division, the ultraviolet band can be divided into UVA, UVB, UVC different wavelengths. UVC is the shortest wavelength energy of the highest band, in fact, for sterilization, the real most effective is UVC this is called deep ultraviolet band. The advantages of UV light over chemical sterilization are high sterilization efficiency, inactivation is generally accomplished within seconds, and no other chemical contaminants are produced.
UV light can also inactivate microorganisms. Homes can purify water by installing a UV water purification system, and air purifiers with UV lamps can harmlessly treat bacteria floating in the air. UV germicidal disinfection is also used in sewage treatment plants, food plants, breweries, beverage plants, etc.
Ultraviolet germicidal lamps should be purchased according to demand
UVC germicidal lamps can be divided into double-ended lamps, single-ended lamps and self-ballasted lamps according to the shape of the three categories, according to whether ozone-containing types are divided into ozone-containing and non-ozone-containing two kinds.
Wang Di, an engineer at the Health Appliance Testing Center of the China Household Appliance Research Institute, said try not to use ozone lamps in crowded places and indoors. Consumers should pay attention to the relationship between UV intensity and space size when purchasing germicidal UV lamps. Usually, each cubic meter of space needs 1.5W of UV germicidal lamp, users can choose the corresponding power size products according to the actual situation at home.
UVC germicidal lamps are usually used in places where bacteria can easily grow, such as kitchens, bathrooms and other dark and damp places, but can also be used in spaces that require high environmental quality, such as wards, operating rooms and other medical facilities. UV germicidal lamps are now also widely used in some electrical appliances, such as air purifiers, fresh air conditioners, clothing care machines and other indoor purification devices and clothing care disinfection devices.
It should be noted that UV lamps have a certain lifespan, so be careful to replace the lamps in time when they are in use. According to the requirements of GB/T 19258-2012 standard, the life of UV lamps is not less than 5000h, the average life is 8000h, and high performance products can reach more than 10,000 hours. Wang Di advises consumers to replace the lamp every 1-2 years and wipe the outer surface of the lamp with alcohol every two weeks to ensure the intensity of UV radiation.
Tips for using UV germicidal lamps
Due to the damaging effects of UV light on biological cells, when using germicidal UV lamps, care should be taken not to directly irradiate the human skin, not to mention to look directly into the lamp with the eyes.
How to use UV germicidal lamps scientifically and effectively in the interests of safety? Wang Di said to pay attention to the location of the placement, create the best use of the environment, while paying attention to the length of use.
First, because the ultraviolet light penetrates very weakly in the air, it is difficult to achieve long-distance germicidal ability, so in use should be placed in the main germicidal location, such as the middle of the room, or easy to breed bacteria, 1.5m-2m away from the surrounding is appropriate.
Second, when using it, pay attention to the effect of the environment on the sterilization effect. Usually, the temperature between 27°C and 40°C UV output strength is the greatest, the best germicidal effect, in addition to ensure the use of the environment is clean and dry, a large amount of moisture and dust in the environment, will have an interference and weakening effect on the UV, reducing the actual UV intensity. When using at home, try to close the doors and windows, close the curtains and turn off the lights to ensure that the room is in a darker condition, more conducive to the ultraviolet light to play a germicidal role.
Third, UV germicidal lamps should be used to ensure adequate UV exposure time. Research shows that after 5 minutes of irradiation, for effective disinfection time, when it reaches 30 minutes, it can achieve daily disinfection effect, when the irradiation time reaches 60 minutes, it can kill most of the bacteria and other microorganisms in the air.
Yan Jianchang said, currently in the civil and industrial fields of sterilization applications of deep ultraviolet light sources are mostly mercury lamps. The future based on gallium nitride broadband semiconductor material deep ultraviolet LED is expected to replace the traditional mercury lamp, its application scope is more easily expanded to portable disinfection electronic products, such as mother and child sterilizer, elevator handrail sterilizer, mini washing machine built-in UV sterilization lamp, floor sweeping robot, etc.
In short, in daily life, “go out less, don’t eat together, wash your hands more often, more ventilation” is still the least expensive and most effective means of prevention. In the face of the epidemic, the use of ultraviolet germicidal lamps for germicidal disinfection must be scientifically and reasonably standardized, and should attach great importance to the use of safety.