Ultraviolet light has gotten a bad rap in some circles, and rightly so to some degree because of its effect on skin. Too much UV light from the sun (which contains the harmful UVA and UVB type rays) has been shown to be completely linked to skin cell carcinomas and other types of cancerous growths. At the same time, getting some UVB rays from sunlight is essential, converting vitamin D3 in our skin to its usable form, which is important for a variety of metabolic functions, immune system and many other things. UV light also has some benefits in the home-for better air quality.
UV light has been used for years in all sorts of medical applications to sterilize and disinfect, and it does this very well with just a few seconds of exposure. Consequently, researchers found that UV light in air conditioning ducts really did a number on any bacteria, mold or viruses floating in the air-in fact, with enough UV light, they got a consistent 95% plus kill the first time the air passed by the bulbs. And we say 'bulbs' because in those tests, there were two UV bulbs of 36 watt strength. When you have two bulbs at 36 watts, placed 30 inches apart from each other like they did in the laboratory tests, you get a full 48,000 UV light units which is enough to kill over 95% of all strains of bacteria, mold, viruses, even algae.
And while UV light bulbs are not 'air filters', they do kill the organisms that cause health problems, cause many of them to drop out of the air, and produce OH- ions, which enhance the effectiveness of many air purifier and HVAC filters. UV light used in air conditioning ducts has been so effective that most allergy or respiratory sufferers surveyed say that their symptoms were drastically reduced or eliminated in as little as 48 hours after installation. For anyone with a compromised immune system, or the elderly, a UV system in the air conditioner ducts could make a big difference in their health, since this stop the constant reinfection from airborne bacteria, viruses, mold and other germs.
If you want the best air quality benefits from ultraviolet light, it's best to get it from UV lamps installed in your HVAC ducts, mainly because it's the strength of the bulbs and the fact that all of the air in your home is being sanitized, not just the air in one room (as in a room air cleaner with UV bulbs). Most air purifier UV bulbs are everywhere from 10 to 20 watts and help some, but do not provide enough light units to kill many species of bacteria, mold, or other germs.
UV light air cleaners are very cost effective for indoor air disinfection, with several high quality two-bulb systems for around $ 500, which is less than most top-rated air purifiers. Just make sure that whatever UV system you choose that it has two 36 watt bulbs and that they are installed 30-36 inches apart on the output side of your air conditioner. Installing a UV lamp air purifier system on the output side allows any pollutants being released from the coil to be sterilized, as well as the air coming into the unit.
To Your Health!