Dr. Gavin Macgregor-Skinner

The latest cleaning technologies, tools, and products have made “cleaning for health” a reality for industry professionals. These technologies have advanced since the early 1900s, when an understanding on how to disinfect drinking water with chlorine helped control and end many diseases, such as typhoid fever, which is caused by salmonella bacteria. Since then, we’ve created vaccines and medicines for respiratory viruses, which continue to impact the daily lives of people around the world. As we enter 2024, facility managers and cleaning professionals continue to face challenges in eliminating infectious, disease-causing germs from the built environment while staying within their budgets. These germs can spread directly from person to person, indirectly through the air as small droplets or tiny aerosol particles, or through high-touch surfaces that have been contaminated by pathogens from the air or from a person who is sick. Indoor air quality (IAQ) strongly impacts respiratory health. The cleaning industry plays an important role in reducing the transmission of respiratory diseases through the improvement of IAQ. Today, we have more tools available to fight respiratory infections, including both nonchemical and chemical-based cleaning and disinfection; air filters and purifiers; ventilation, filtration, and increased air exchange through HVAC system improvements; and ultraviolet (UV-C) light systems. Through ISSA’s GBAC® STAR facility accreditation program, we are seeing facility managers take a more evidence-based and systematic approach to reducing the risk of infectious disease spread inside their buildings by implementing a layered approach to cleaning and disinfection, which is the strategy recommended by the Global Biorisk Advisory Council® (GBAC), a Division of ISSA. Germicidal ultraviolet light (UV-C) technology, specifically, can be effective in many indoor spaces and is especially useful as an additional layer of protection to reduce infectious germs. It is also helpful when options for increasing room ventilation and filtration are limited. UV-C light disinfection is growing in popularity. The global UV-C disinfection equipment market was valued at US$1.3 billion in 2019 and is projected to reach $5.7 billion by 2027, growing at a compound annual growth rate (CAGR) of 17.1% from 2020 to 2027, according to a report published by Allied Market Research. CMM reached out to Doug Hoffman, the executive director of the National Organization of Remediators and Microbial Inspectors (NORMI™), and Dr. Gavin Macgregor-Skinner, senior director of GBAC, to learn more about IAQ and the role UV-C can play as an effective tool against infectious airborne diseases. What’s the problem with current IAQ standards? Dr. Gavin Macgregor-Skinner Current IAQ standards do not consider infectious disease risk and include airborne pathogen levels. Very few buildings measure their indoor air quality, even though indoor air quality monitors are available and affordable. There’s a lack of standards, education, and training on the implementation and costs of deploying a layered approach to improve IAQ. Doug Hoffman We need to implement a layered approach and mass deployment of IAQ interventions that includes ventilation, filtration, air ionization, photocatalytic oxidation (PCO, which is explained further in the Q&A), and ultraviolet germicidal irradiation (UVGI). We have training on effective interventions to improve IAQ, and we have tools to measure it as well. How does UV-C light disinfection work? Macgregor-Skinner UV-C radiation is a known disinfectant for air, water, and nonporous surfaces. It has effectively been used for decades to reduce the spread of bacteria, such as tuberculosis. For this reason, UV-C lamps are often called “germicidal” lamps. UV-C radiation eliminates the outer protein coating of bacteria and viruses, ultimately leading to the inactivation of the microorganism. Hoffman UV-C light’s efficacy is dependent upon the organic load and microorganisms, the intensity and time of exposure, the distance from the surface, and whether the surface is within direct line of sight. UV-C light can only inactivate a germ if the germ is directly exposed to the light. UV-C light requires a sufficient duration of exposure to be effective, and this can vary for different microorganisms—bacteria, viruses, fungi. What is the correlation between wavelengths and germicidal irradiation? Hoffman Humans can see visible light as waves of electromagnetic radiation between about 400 to 700 nanometers (nm). A nanometer is one-millionth the size of a millimeter. Radiation with wavelengths just longer than visible light is called infrared, and longer radiation wavelengths than this are radio waves. Radiation with wavelengths just shorter than visible light is called ultraviolet, and shorter radiation wavelengths than this are X-rays. Ultraviolet (UV) light is subdivided into UV-A (315–400 nm), UV-B (280–315 nm), and UV-C (100–280 nm). UV-C is effective at killing a wide range of microorganisms, including viruses. When a light looks like UV (like a blacklight), it might not be at a wavelength that can kill or deactivate microbes. The only way to know for sure that you are using the right UV-C light is to find the wavelength the light is generating. The manufacturer, of course, will provide that information. Macgregor-Skinner The UV-C disinfecting process, UVGI, uses short-wavelength UV (200–280 nm) light to kill or inactivate microorganisms by disrupting their genetic material (DNA or RNA), leaving them unable to perform vital cellular functions and resulting in cell death. The Tuberculosis Ultraviolet Shelter Study, conducted at 14 homeless shelters in six U.S. cities from 1997– 2004, found that UV-C lights placed at least 6.9 feet above the floor could disinfect the air and were safe for humans with no increase in the most common side effects of accidental UV-C exposure. Where can you put UV-C lights in the built environment? Hoffman UV-C technology can be installed in HVAC systems, packaged terminal air conditioners (PTACs), heating systems, fresh-air makeup devices, and other air-conditioning equipment to address the air in any environment. However, not all the air always gets to those devices so having this technology in standalone units is sometimes the best option. For those who use their air conditioning and heating systems sporadically, a combination of technologies is a wise choice. Macgregor-Skinner GBAC STAR-accredited facilities, which includes airports, hospitals, hotels, nursing homes, office buildings, schools, and stadiums, have made significant improvements implementing a layered approach

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Dr. Gavin Macgregor-Skinner

Senior Director, GBAC

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