Till recently it was believed that HEPA purifiers are good enough to tackle the problem. Any HEPA purifier has the ability to trap contaminants of the size of 0.3 microns and above. Though such filtration takes care of a lot of contaminants, there are still a significant number of contaminants which still need to be dealt with. But they being less than 0.3 microns in size, are not trapped by the HEPA purifier.Viruses are too small to be trapped by a HEPA air purifier, which will capture most bacteria.
The recent innovation has been ultraviolet air purifier. These come either in conjunction with HEPA purifiers or as stand alone machines. The ultraviolet air purifiers work on a totally different concept. Studies have shown that UV rays are effective in dealing with microorganisms of size even less than 0.3 microns in size.
An UV air purifier actually doesn't kill the organism. Instead the rays just alter the DNA and RNA profile of the organisms. This makes them sterile so that they in a way become harmless. With no option of reproducing they can hardly cause any damage. So even if virus and bacteria do enter our respiratory tract they hardly get a chance to grow there.
Upon the introduction of ultraviolet air purifier in 1990, many have used this device to make their environment safe. This helps remove substances in the air to provide fresh and clear air in the office, in the hospitals, in different establishments and even inside one’s home.
Ultraviolet light utilizes its energy to break down the organic molecular bonds of the micro-organisms, due to which the organism is destroyed. In an ultraviolet air purifier, the particles and organisms present in the air enter the purifier and while passing by the UV rays, their molecular bonds are broken and destroyed. The purifier then gives out air that is cleansed and free of any harmful particles.
Air purifiers with UV-C light use a relatively short wavelength of 254 nanometers, a time proven method of disinfection. The bug’s DNA is damaged, making reproduction difficult. Germs cannot develop immunity to this physical assault, and viruses are very vulnerable due to their lack of protective cell walls.
Ultraviolet light can alter the DNA and RNA profiles of the allergens only after they are exposed to the light for a considerable period of time.Microbes must be exposed to UV light long enough for their internal structure (DNA and RNA) to be damaged. The dosage or concentration of light on the contaminants is also crucial.
Skeptics claim that within an air purifier, the ultraviolet light doesn't get enough time to act. Since a fan is always working the organisms never settle down. With the contaminants unsteady the UV rays cannot work on them.
A conflict is created between the need for higher fan speeds, to clean the air of other particulates, and effective air sterilization. Either the light is less effective or not enough air is purified.
Advantages :
- UV air purifiers prevent airborne diseases like allergy, flu, pneumonia, tuberculosis, and asthma by disinfecting the air and efficiently destroying the particles and organisms that can cause these diseases.
- They prevent the growth of molds in central air conditioners and cooling coils, thus eliminating the need to clean them regularly.They keep the room fresh and clean by eliminating odors.
- They destroy volatile organic compounds (VOCs). Volatile organic compounds are harmful gases/vapors emitted by various products.
Disadvantages :
- UV-C has low skin penetrating capability. It will irritate the eye, but is believed not to cause cataract or cancer. UV-C does not pass through eye glasses or clothing.
- Exposure to UV-C can cause temporary skin redness. Nobody should look at the bulb and the power should always be turned off before servicing or replacing the lamp.
- The UV lamp in the air purifier needs to be changed once in two years and the dust collection plates need to be cleaned regularly with a damp cloth.
