At the front end of the pandemic, a customer at a restaurant in China infected nine others with COVID-19. Some were seated about 14 feet away from her. The Centers for Disease Control and Prevention (CDC) suspects the restaurant’s heating, ventilation, and air conditioning (HVAC) system spread the virus through the five-story, windowless building. So, if HVAC can broadcast COVID-19, can it also snuff the virus out?
A technology called ultraviolet germicidal irradiation (UVGI) boasts a strong track record against a laundry list of pathogenic microorganisms. That’s scientist-speak for tiny things that make us sick. If your organization is exploring UVGI, you should learn the basics and follow these tips so you can make a responsible decision for staff and students.
What about the six-foot rule?
Social distancing guidance is based on a simple premise. When an infected person talks, coughs, sneezes, or sings, they spray respiratory droplets into the air. Because the droplets are heavy, they travel a short distance—no more than six feet—before falling or landing in someone’s mouth or nose. The World Health Organization, however, recently acknowledged the potential for airborne transmission driven by virus particles called aerosols.
Like respiratory droplets, aerosols are expelled from an infected person’s nose or mouth. Unlike droplets, aerosols are light enough to float and catch a ride on air currents. The possibility that COVID-19 is airborne does not mean the six-foot rule goes out the window.
Scientists stand by their claim that the virus primarily spreads through close contact with infected people. The emphasis is on primarily, however, and the stakes are high. With other pandemic expenses claiming budget space, is UVGI a worthy investment?
Long on promise, short on science
The notion of harnessing ultraviolet light to eviscerate what ails us is not new. It’s been tackling mold, fungi, viruses, bacteria, and germs for more than a century. UVGI’s superpower lies in its ability to kill a microorganism or inactivate it by damaging its DNA.
UVGI systems are powered by lamps that shine germ-killing UVC light on surfaces or on the air we breathe. Their effectiveness depends on multiple factors, such as humidity, ventilation, lamp intensity, lamp location, and length of exposure. UVGI has been enlisted to fight flu, tuberculosis, measles, and even other coronaviruses. But does it kill COVID-19?
The answer is long on promise and short on science – for now. Because COVID-19 is new, researchers are still investigating whether UVGI can kill the virus or wreak havoc on its genetic bits and pieces. The good news is that evidence from credible sources makes a plausible case.
The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) says UVC kills 90 percent of microorganisms living on HVAC air ducts and evaporator coils. With personal protective equipment for health care providers in short supply, the National Institute for Occupational Safety and Health pegged UVGI as one of three promising strategies for decontaminating respirators.
Columbia University Irving Medical Center has generated two significant studies on coronavirus and UVGI. Researchers found the technology killed more than 99.9 percent of seasonal coronaviruses in airborne droplets. Preliminary results of a follow-up study suggest UVGI is just as effective at killing airborne SARS-CoV-2, the virus that causes COVID-19.
Use these tips to guide your decision
Most of us can rattle off basic COVID-19 safety guidelines as easily as our birthdates at this point in the pandemic. Social distancing, wearing our mask, washing our hands, coughing into our elbows, and disinfecting commonly touched surfaces are easy to wrap our heads around, if not enforce. Exploring UVGI, however, might take your organization out of its comfort zone. Use these tips to guide your decision.
Learn the options. There are two primary ways to leverage UVGI in your pandemic mitigation plan. Upper-room fixtures are mounted on walls in rooms where ceilings are at least eight feet high. Air enters the disinfection zone as it circulates vertically through the room. UVGI lamps can also be applied to HVAC units. In-duct systems treat air as it flows through the ducts. Coil systems focus on the cooling coils and drip pans. Research the options before you shop, and learn their pros and cons.
Understand how coatings affect intensity. It is not uncommon for UV lamps to include coatings that make them environmentally safer and extend their lifecycle. Coatings can also reduce the intensity of UV light released. Ask vendors if their systems use coatings that compromise their ability to kill or inactivate microorganisms.
Request data. The scramble to safely reopen our economy revived interest in UVGI and fueled competition. Unfortunately, some products and new technologies do not live up to their promises. Remember that scientific studies of UVGI’s effectiveness against COVID-19 are pending. Ask contractors for manufacturer-produced disinfection reports before purchasing a system.
Look past the pandemic. As you weigh whether to invest in UVGI and other solutions, consider whether they will deliver benefits when the pandemic subsides. By targeting microorganisms, for example, UVGI can make your HVAC system run more efficiently, reduce system maintenance costs, and improve air quality.
Account for long-term costs. The energy required to power UV lamps is a primary long-term cost of operating a UVGI system. Those costs cut into energy savings associated with cleaner, more efficient HVAC. And just like roofs, UVGI systems require routine maintenance. For example, most lamps need to be replaced every one-to-three years and regularly cleared of dust.
Hire trained professionals. UVGI can harm the skin and eyes, as well as damage HVAC filters, sealants, and other components. Broken lamps could also expose employees to dangerous mercury. It is important that you hire trained professionals to install, inspect, and maintain your UVGI system.
Don’t implement UVGI in a vacuum. UVGI is not a COVID-19 cure-all, but it can be an important piece of a comprehensive indoor air quality program. The Environmental Protection Agency advises organizations to prioritize ventilation and filtration in facilities. ASHRAE recommends filters with a MERV 13 rating or higher for COVID-19 mitigation. Austin ISD’s return-to-school plan takes expert advice to heart by using fans to improve air flow and installing HEPA air filters in small spaces. Grape Creek ISD researched what schools around the world did to bring students back before investing in UV lights for every classroom.
Get more information
ASHRAE offers position documents that provide comprehensive, research-backed guidance on topics such as infectious aerosols, filtration, and air cleaning. The association’s epidemic task force also developed resources specifically for schools. For additional expertise, Fund members can contact your risk solutions consultant.