Ultraviolet (UV) light has long been known for its purifying power. Used at certain dosage it helps to destroy all the airborne pathogens, such as bacteria, viruses, mold etc. UV purifiers were first used in cleaning other substances, such as water, from various pathogens. A first UV air purifier was constructed a few decades ago and was first used in medical and dental facilities. These devices were then modified and commercialized and are now available for residential and commercial purposes. Nowadays there are many different companies that produce UV air purifiers alone or in combination with other air cleaning devices, most frequently with HEPA air filters.
The purpose of UV air purifier
Various UV air purifiers are used to eliminate airborne infection in medical or dental objects, or in any other places where a big risk of infection exists. The method used in air purifiers of this kind is called Ultraviolet Germicidal Irradiation (UVGI). Due to the small size of various viruses and some bacteria, they cannot be caught and eliminated from the air by simple media filters. Hence a UV air purifier is needed to clean the air from airborne pathogens and prevent from the spread of infection. Airborne microorganisms are being eliminated from the air when exposed to specific levels of UV radiation. These levels vary with the type and concentration of bacteria or viruses present in the air.
Moreover, UV light can be a strong weapon for destroying other pollutants and allergens in the air, such as dust, pollen and toxic volatile substances. This is maintained due to photochemical process, which takes place when particles are exposed to UV light energy. When this process reaches certain level, UV light is useful and effective in destroying the above-mentioned particles as well as biological contaminants, such as bacteria, viruses and fungi. UV air purifier usually consists of two main parts: a UV lamp and a media filter. A filter may be flat, pleated of high efficiency particulate air (HEPA) filter. Aflata air purifier filter generally consists of a low packing substance and is not efficient enough when used without UV lamp. A pleated filter has an increased filter density and hence higher efficiency in clearing smaller particles from the air. And finally, a HEPA filter is considered to be the most efficient air-cleaning device that has the ability of eliminating at least 99.97% of all airborne particles of 0.3 micron diameter and larger. HEPA filter is therefore most frequently used in UV air purifiers. Another part of UV air purifier is a UV lamp, which has a germicidal power against biological airborne pollutants. The germicidal efficiency of this lamp, and hence of a whole UV air purifier, depends on the time of exposure of a microorganism to the killing UV light and the intensity of UV lamp. Different airborne pathogens require different levels of UV light and different exposure times.
Ultraviolet lamps
UV lamps are most effective in still air at an average temperature of 23 degrees Celsius. In general, one should know that the greater the size of the UV lamp, the bigger the output of ultraviolet germicidal irradiation. However, not all the companies have UV air purifiers that emit a high UV dosage that is required in order to kill various germs and viruses. Such UV air purifiers have a UV lamp only to maintain filters clean from fungi and bacteria growth. These devices cannot destroy airborne microorganisms since their UV dosages are too low. UV air purifiers are available for private and medical facilities. In residential areas and homes these devices are used in a portable mode whilst in medical facilities and hospitals they may be installed into walls and ceilings. UV air purifiers are a must in hospitals, medical or dental facilities and should be located in emergency rooms, surgery theaters, general wards of infectious patients and other areas of high risk of airborne infection. When residential or home UV air purifiers are considered, it is every person’s decision whether to use it or not. UV air purifiers are very helpful to people who suffer from different allergies, since these devices clear the air from various allergens, including dust and pollen. People who suffer from frequent respiratory tract diseases and infections of different body organ systems may also choose a UV air purifier due to its high efficiency in destroying airborne microorganisms.
UV air purifier and HEPA filters
There are a lot of various investigations made in order to find out more about the benefits of the use of UV lamps and HEPA filters in the same unit. All of them claim that UV air purifiers are more efficient than HEPA filters alone, since some viruses can penetrate HEPA filter. A UV air purifier makes the viruses impossible of such action. Some research results show that the use of UV air purifiers in the ventilation system helps to eliminate up to 99% of all airborne germs. Even more, it has been shown that people residing in the area maintained with a UV air purifier have less respiratory symptoms and complaints as well as less work-related breathing problems. Therefore, U.S. Centers of Disease Control recommend to apply UV air purifiers and HEPA filters not only in medical facilities but also in government buildings, residential areas, restaurants, schools and kindergartens in order to increase indoor air quality and prevent from infectious diseases. Moreover, there are some recommendations to use UV air purifiers in homeless shelters in order to stop the spread of dangerous airborne infectious diseases, such as tuberculosis (TB). When the price of UV air purifiers is considered, they are not much more expensive than HEPA filters alone. The price differs with the manufacturer but is at a decent level, especially considering all the advantages of a UV air purifier . UV lamps may be used for up to 5 years and then should be changed if they are not working properly. However, the lifetime of UV lamps may vary with different manufacturers and types of lamps.
Advantages and disadvantages of UV air purifier
It is very important to mention, that UV light may be destroying to people’s skin and eyes when exposed directly at high levels. However, there is no doubt that UV air purifiers are safe when used in inhabited areas and are of no damage to people. This is provided by the mechanism that UV light acts isolated only in the air-cleaning device. Hence, only the air that passes through a UV air purifier is affected by UV light power and is being sterilized. UV light does not escape the device and therefore cannot affect people in the coverage area. Scientists claim that intense sunlight kills or destroys most of the airborne microorganisms in the outdoor air. The indoor air is from 6 to 10 times more contaminated with dangerous germs compared with the outdoor air. Therefore UV air purifier is a possible effective option to improve the quality of indoor air, destroy all the airborne pathogens, purify the air from various allergens and maintain an efficient disease and infection control. Due to these abilities and advantages, UV air purifiers are becoming more and more popular among people worldwide.
