DALLAS — The use of germicidal lighting to combat germs and viruses, including COVID-19, is a hot topic. Germicidal ultraviolet “light” or GUV refers to the technology of germicidal lighting, which utilizes ultraviolet-emitting sources. While GUV has great opportunity, it is more complicated than simply turning on a UV light. Terry McGowan, FIES, LC, director of technology for the American Lighting Association (ALA), explains that it is imperative to be cognizant of the safety and efficacy issues of using germicidal lighting, and to be educated about the capabilities of the different types of UV light.
Knowledge
It’s important to be aware of what type of UV is being considered for germicidal purposes. The part of the electromagnetic spectrum involved consists of three UV regions:
- UV-A – traditional blacklight used in insect traps and theatrical settings, abundant in natural sunlight and daylight
- UV-B – also present in sunlight, excessive exposure causes sunburn, repeated exposures can result in skin cancer
- UV-C – germicidal lighting, requires strict precautions, damaging to eyes and skin, not present in sunlight
UV-A and UV-B are not virus killers. It is only the UV-C part of the spectrum that can decimate viruses, including COVID-19, when used appropriately. When considering UV for germicidal purposes, carefully read all application, safety and caution notices, and ensure the product is emitting UV-C. The information should include exposure requirements, including maximum distance between the source and materials to be exposed, plus exposure time required for disinfection. If the information is unavailable, insufficient, or difficult to understand, do not use the product.
Safety
UV lighting products, particularly those emitting UV-C, can cause eye and skin damage to humans, pets and home furnishings. With proper precautions and knowledge, it is possible to use UV-C products safely; to be effective, exposure time and distance must be correct. Like sunburn, damage to skin and eyes will result from being exposed for too long to the light source. Complicating matters are the many unsafe products on the market touting unrealistic claims without listing the dangers they pose.
In homes, UV-C can disinfect air circulating through HVAC systems by placing the source in the return air duct near the heating/cooling coils where they remove germs from the air and kill mold and bacteria that collect on the coils, especially in humid weather.
Efficacy
In addition to requiring proper dosage, germicidal lighting only works via line-of-sight. Reflected light does not kill germs because most reflecting surfaces in homes absorb the critical UV wavelengths. For example, any clothing or masks with folds or wrinkles will not be disinfected in those hidden areas not directly exposed to the light.
UV for disinfection is only thoroughly effective when using the UV-C part of the spectrum in strictly regulated environments where people are not present, such as healthcare settings. Find more information at ALALighting.com/Home/Germicidal-Ultraviolet-Light.
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