Do UV Lights Kill Mold and Bacteria?
UV works! Ultraviolet lights were shown to kill mold, viruses and bacteria more than 100 years ago. In fact, in 1903, Niels Finsen was given the Noble Prize in Medicine for using UV to effectively treat patients with skin infections.
Today, UV lights are used for germicidal use in hospitals, restaurants and grocery stores. And they have been shown effective in killing sterilizing an HVAC system. Here are two examples:
1). In 2012, a study at Duke University Medical Center showed that UV lights killed 97% of bacteria that were resistant to antibiotics, the so-called superbug bacteria that are the toughest to kill.
2). The Journal of Applied and Environmental Biology reported in 2001 that germicidal UV radiation significantly reduces airborne fungi in air handling units.
How HVAC UV Lights Work
UV lights are effective, but they work in a specific range. They’ll kill organic growths, such as mold or bacteria, but they have no effect on dust, pet dander or other allergens. In most residential cases, an HVAC company will install the UV light near the coils to prevent mold or bacteria growth as air passes through. Since all of the air passes through the coils, this also kills growths in the air. UV lights are particularly effective in humid climates, where evaporator coils can easily get wet.
Goerge Klein, vice president of Pipe Doctor of Queens recommends UV lights to homeowners with severe allergies.
“It’s not 100 percent, but they really reduce a lot of those common allergens,” he says. “They’ll kill bacteria and get a lot of those mold spores before they get blown into the system. I’ve taken air quality tests before and after these systems are put in, without any other remediation or abatement, and there’s a significant difference.”
Klein says the cost of the work varies depending on size of the HVAC unit, but she tells homeowners to expect to pay around $1,500 for installation.
Can Ultraviolet Light Kill the Novel Coronavirus?
UV light has been used widely in disinfection with a wide range of medical and non-medical products available in the market. In the time when the whole world is fighting against the coronavirus outbreak, LEDs that deliver virus killing UV lights might be a practical solution for preventing infection.
UV light is germicidal because it inactivates microorganisms by destroying nucleic acids and disrupting their DNA with its short wavelength. In addition, oxygen can also absorbed energy from UV light to form ozone for disinfection.
According to current understanding, UV light with a wavelength of 200-280nm is most germicidal. For different microorganisms, the effect of UV light varies. Mercury light has served as a UV light source for long with a irradiation wavelength of 253.7nm. With improved development in LED technology, tunable LED can deliver UV light with specific wavelengths. UV LED-based applications with increased power and tunable wavelengths are expected to be the next-gen disinfection products for medical uses.
The effect of UV germicidal irradiation depends on the temperature and humidity of the environment. The suggested time for UV light exposure is at least 30 minutes but it will take longer time to achieve the same effect when it is below 20 degree or over 40 degree Celsius and relative humidity exceed 60%. To more effectively and efficiently destroy bacteria and viruses, NSF International has revised drinking water treatment standard with UV LED technology included.
The novel coronavirus is a kind of positive-sense single-stranded RNV virus, same as the SARS and MERS virus. Researches on SARS found that this kind of virus is sensitive to heat radiation and UVC light and can be diminished when exposure to UVC irradiation stronger than 90 μW/cm2. Thus, in theory, UV light would be able to destroy the novel coronavirus (2019-nCov). However, no further research has shown the effect of UV light on viruses attached to droplet at the moment.
To prevent infection, washing hands often with soap and water and use alcohol to sanitize hands are still critical way to avoid spreading of viruses.
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We have installed hundreds of UV Light Purification systems since 2009.
UV-Aire Purification System
Field Controls offers a complete line of UV-Aire products for any home or business, with a variety of duct-mounted models designed for forced-air heating and cooling systems. UV-Aire germicidal lamps continuously attack airborne mold, bacteria, and viruses as they circulate through your duct work. As part of the Healthy Home System, the in-duct UV-Aire works with the Healthy Home System Control to ensure PURE air in the home all year round…even when not heating or cooling. The UV-16 Remote models fit in tight spaces due to their compact design and include a built-in safety switch to enable the light only inside the duct.