Germicidal UV Light and COVID-19

The current COVID-19 pandemic has caused a surge of interest in using Germicidal UV (GUV) lamps for sanitization purposes. This is a new and evolving procedure that requires knowledge about the science, effectiveness and safety of any UV products. To avoid liability from dangerous UV overexposure conditions, as well as unrealistic expectations of ineffective GUV systems, research the options from reliable sources. Here is some insight into what the industry knows and offers so far.

How GUV is applied

  • Specialized indirect GUV installations, carefully shielded from eye level, are occasionally used in hospitals and labs to control airborne pathogens.
  • Low-pressure mercury GUV airflow scrubbing systems can help reduce mold growth in commercial HVAC systems.
  • Mobile GUV devices for surface disinfection may be used to treat high-touch surfaces, such as elevator buttons, light switches and keyboards.
  • Intermittent, whole-room ambient GUV disinfecting may also be effective, but it requires occupant lockout for their protection.

These specialized applications require specific understanding of GUV effects, dangers and adherence to industry guidelines.

Science matters

UV light, categorized as UV-A, UV-B, and UV-C, is outside the visible portion of the light spectrum, so we can’t see it. UV-A passes through the Earth’s atmosphere uninhibited, while UV-B is partially blocked by clouds and water vapor. UV-C is entirely blocked by the atmosphere and must be artificially reproduced for GUV. UV-A and UV-B are ineffective at killing bacteria or inactivating viruses, plus overexposure to these penetrating wavelengths can burn the skin and eyes, and at worst cause skin cancers. On the other hand, UV-C’s energetic short waveform can kill bacteria and inactivate viruses. While not as penetrating, UV-C can still cause harmful burns to the skin and eyes. It should only be used in controlled environments that ensure exposure meets recommended guidelines and limitations, such as those addressed in the recent IES CR-2-20-V1 report. No UV product should ever be used for hand sanitization or aimed so that the eye is exposed to it directly; this can be difficult to assure since UV is not visible.

Research the products

Many GUV products have recently appeared on the market, from direct lighting fixtures to ineffective toothbrush disinfectors. However, most of these products actually produce UV-A and/or UV-B, which are ineffective against bacteria and viruses. Some may claim capabilities that are not backed by any certification, testing or labeling. Some may even falsely claim to be UV-C, or are in fact black lights, which also do nothing to fight germs. To be safe before purchasing any products, ask for data sheets, customer references and case studies of recent installations.

Low-pressure mercury has historically proven to be the most effective, efficient and reliable source for UV-C production, and there are credible providers of such GUV systems. While UV-A LED lamps have been available for some time, they are not effective against bacteria and viruses. UV-C is a specialized output for LED, and it will take time to develop LED GUV-C products with proven performance, efficacy and life ratings.

Put safety first

When considering any UV light systems, and GUV in particular, evaluate its effectiveness balanced with consequences to human health and other possible effects. For example, plastics and other materials may be susceptible to photodegradation when exposed to UV light. These materials may fade or become brittle over time. Make sure any products you try are backed up by verifiable data, testing and recommended application practices.

If you would like to talk more about UV applications and other developments, contact Tony Adams, National Lighting Manager, 503.816.2879.