Germicidal UV Light: A Defense Against Airborne Infectious Diseases
Despite the fact that there has been a lot of media hype about an H1N1 ‘swine’ flu pandemic there is, in fact, a very real threat. Influenza viruses invariably evolve and a new strain of the swine flu could potentially become a very serious problem in a short period of time.
Studies have shown viruses can spread through the air as well as by physical contact so a preventive strategy must include an effective method of air disinfection. Hand washing alone will not do the job!
Fortunately an ideal solution already exists. For over a century Germicidal Ultraviolet Irradiation or UVGI has been recognized as a highly effective tool against airborne and surface microbial infection. UV light systems are routinely used for disinfection in hospitals, the food industry, and in water purification.
In recent years there has been a tremendous growth in the number of UV lights installed in HVAC systems large and small as a means to reduce maintenance by suppressing mold growth and to provide healthier indoor air quality for occupants.
These lights are so effective because microbes have no defense against C-band ultraviolet light (UV-C) which is not present in daylight (it’s filtered out by the atmosphere). UV-C light sterilizes germs by penetrating their cell walls and scrambling the DNA inside leaving them incapable of reproduction.
In the past UV light has been shown to be effective against influenza strains (including ‘bird’ flu) as well as SARS, legionella, TB, pneumonia, German measles, and many other airborne infectious diseases.
ASHRAE now recommends the use of UV-C lights within HVAC systems as an effective way to reduce airborne infectious diseases while helping maintain system cleanliness by keeping surfaces free of microbial contamination. A single pass through the air system can sterilize up to 90% of airborne contaminants and a typical air handler will change the air four to five times an hour significantly reducing the risk of airborne microbial infection.