UV-LIGHT AIR PURIFIERS https://www.opticsindia.com/uvc-sterilizing-light/
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Historically, ultraviolet (UV) light has been used to disinfect water, surfaces and the air. You may wonder if this technology works against airborne microbes or generally improves the air quality of your home. This article will describe how UV air purifiers work, whether they have been shown to be effective in cleaning the air and their potential safety concerns.
What are UV light air purifiers? •
UV air purifiers are designed to use short-wave ultraviolet light (UV-C light) to inactivate airborne pathogens and microorganisms like mold, bacteria and viruses. They have the same ultimate goal of all air purifiers: to reduce indoor air pollutants. The technology is also referred to as UV germicidal irradiation, or UVGI air purifiers. This is different from other air purifier technologies that contain UV light technology but do not use it directly against air pollutants.
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On the market, UV-C air purifiers are currently sold as stand-alone, freestanding devices or as systems installed into pre-existing residential or commercial HVAC units. As air is forced through the device, it passes UV lamps, which directly attempt to disinfect the air by means of germicidal irradiation. The biggest safety concern is that ozone may be generated during this process.
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Rarely a stand-alone product, UV-C light air purifiers often require additional systems for full effectiveness and are most often included in larger High-efficiency Particulate Arrestance (HEPA) air filtration systems. In fact, the EPA says that a UV-C air purifier does not seem effective as a stand-alone unit because it cannot trap or remove particles.
Background on ultraviolet light •
Germicidal UV light has been used in the treatment of tuberculosis and to disinfect hospitals, kitchens, meat processing plants and laboratories.
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Electromagnetic radiation takes on many forms–from visible light to radio waves to ultraviolet light. Here is some background on how different forms of light have different energy levels:
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Light is made up of tiny particles called photons. As they travel, they vibrate back and forth and trace a wave in space. The quicker they vibrate, the shorter the distance between each wave. The slower the vibration, the longer the distance between each wave. This wave-to-wave distance is called the light’s wavelength. Long waves with slower vibrating photons have less energy. Short waves with quicker vibrating particles have more energy.
Depending on their molecular makeup, different materials in the world reflect and absorb different wavelengths of light: •
Visible light has a wavelength between 400-700 nanometers long—the range that affects the light receptors of your eyes.
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Infrared light, which you can feel as heat, is longer (700 to 1M nanometers).
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Ultraviolet, which you cannot feel or see, is shorter than visible light at 100 to 400 nanometers.
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Photons transmit electromagnetic energy when they encounter matter, and ultraviolet light has high levels of energy.
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Ultraviolet light: UV-A, UV-B and UV-C
Ultraviolet is split into three sections: •
UV-A light: 315–400 nanometers with photons that vibrate just a little faster than visible light
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UV-B light: 280–315 nanometers, with photons that vibrate even faster
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UV-C light: 100–280, with photos that vibrate the fastest and carry the most energy
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Prolonged exposure to UVC light can cause temporary eye and skin damage, so extra precautions should be taken if directly working with or around UVC lamps. Today, UV light is mainly used to complement other established methods of disinfecting and “sterilizing” sensitive scientific and medical equipment and spaces, though such irradiative cleaning systems have found their way into residential and commercial applications by UV light’s popularization as a purifier in the past two decades. These products fall within the scope and exigency of improving cleanliness and reducing environmental pollution, rather than combating infectiousness.
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