Germicidal Lighting: Less Hype, More Facts

Armed with the knowledge that Germicidal Ultraviolet-C (GUV-C) Light possesses the proven ‘superpower’ of eradicating harmful viruses including COVID-19, many people have begun searching for ways to safely incorporate it into their everyday lives. But, with new products hitting the market daily, consumers can easily become overwhelmed and confused given the enormous amount of conflicting information being offered around every turn. Recently, the term fluorescent has been added to the description of some GUV-C products in hopes of providing a level of comfort and familiarity to the many consumers already using this traditional light source in their workplaces and homes. But, as expected, this has only added to the level of confusion and raised even more questions about the safety of GUV-C Lighting as well as fluorescent. So, here we take a closer look at the defining characteristics of these two light sources to better understand why their similarities and their differences are so important.

The Similarities

  • Basic Technology – Both GUV-C and fluorescent are types of gas discharge lamps. They use the same low-pressure mercury vapor arc technology to produce ultra-violet radiation inside their arc tubes.
  • Ballasts – Both lamp technologies require a ballast to operate properly.
  • Overall Appearance – GUV-C and fluorescent lamps are manufactured in the same sizes, shapes (T5, T8, Twin Tube), and base styles (2-pin, 4-pin, linear bi-pin, screw-in, plug-in).
  • Environmental Hazard – GUV-C and fluorescent lamps contain mercury and are therefore considered to be hazardous to the environment if not disposed of properly through recycling.
  • Temperature Sensitivity – The performance of GUV-C and fluorescent lamps is affected by the surrounding air temperature. Below 50-degrees Fahrenheit, the lamps may have trouble starting and will have trouble operating at their peak light output. The colder the surrounding air temperature, the worse the performance.

The Differences

  • Glass Coating – The GUV-C lamp is made of a special clear glass that allows the powerful 253.7nm wavelength ultra-violet radiation to transmit through while remaining invisible to the naked eye. In comparison, the fluorescent lamp has a phosphor coating inside the glass which makes the lamp look white in color and converts the same ultra-violet radiation into usable visible light.
  • Suggested Applications – GUV-C lamps are often used in sterilization and disinfection processes including those for water purification, air conditioning, and food/pharmaceutical processing. Fluorescent lamps are commonly used for lighting many different space types in both residential and commercial settings.
  • Interaction with Humans and Animals – For GUV-C lamps, direct contact with humans and animals should be avoided at all cost. The invisible ultra-violet radiation can cause photokeratitis (otherwise known as welder’s flash) which temporarily damages the cells on the surface of the eye. Although usually not permanent, the symptoms can be very painful for up to 48 hours after exposure. Fluorescent lamps do not pose a risk to humans and animals. However, they have been known to fade some materials and textiles after prolonged exposure.
  • Expected Lamp Life – The average life of a GUV-C lamp is 9,000 hours which equates to a little over a year for lamps running continuously to disinfect and sterilize. The average life of a fluorescent lamp is a much more palatable 20,000 hours. Plus, fluorescent lamps are usually governed by code-required lighting controls which automatically turn the lighting off after a set period of time exponentially elongating the lamp’s life.
  • Average Cost – Depending on the exact specification and manufacturer, the cost of a GUV-C lamps can vary widely from as little as $26 for a small compact version to $75 for a larger linear lamp. Leading most to purchase these lamps in a small quantity and only for very specific applications. In comparison, fluorescent lamps have a much lower cost due to their use in much larger applications. They range from $3.50 to $5.50 per lamp and are usually bought by in bulk quantity.

Based on the above information, one can see that GUV-C and fluorescent lamps are no doubt closely related. However, their differences are what provide the real guidance for their rightful place in our everyday lives. If you have any questions, please do not hesitate to contact Jennifer L. Harrington, PE at or 814-237-2180.

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