Healthcare-acquired infections (HAI). An individual who picks up an infection while receiving care in the hospital will likely require a longer stay, which is very expensive for the healthcare system. In the worst case, they become seriously ill and die.

The Center for Disease Control reports that healthcare-acquired infections kill around 100,000 people every year in the US.

We need some fresh ideas to deal with HAIs, but which infections specifically? This broad spectrum of infections can include complications from surgery or a non-sterile instrument, or from a lack of hand washing, or an encounter with dirty surfaces. Let’s look at one narrow subset of these infections, Clostridium difficile, which most commonly affects older adults in hospitals or in long-term care facilities. These infections can come from diarrhea. It aerosolizes, the bacteria lands on a surface, they colonize, someone makes contact with that surface, that gets in their body, and they’re sick. This especially happens in hospitals with shared patient rooms and shared patient washrooms. Many hospitals, usually older ones, have wards where you have six beds and one shared bathroom. According to the CDC, C. diff attacks 500,000 US patients every year and kills 15,000 of them within 30 days of being diagnosed.

Here’s where the lights come in: Ultraviolet Germicidal Irradiation using Ultraviolet C (shortwave ultraviolet light) lighting, or UVc, for short has great potential. Use of UVc is well established in the water treatment industry, but its implementation in healthcare is not yet widespread. UVc lights used frequently to kill germs in the hospital water supplies, air handling equipment, and sterile device processing. But the application of a UVc lighting system in shared bathrooms to irradiate C. diff germs after the bathroom has been used still appears to be the exception, instead of the rule.

The second area in healthcare where UVc may be beneficial in controlling biofilm. Biofilm, which is like that slime that accumulates on children’s bathtub toys, isn’t necessarily bad bacteria, but when we see it in healthcare settings—where we have sick and vulnerable patients—it becomes undesirable. With a UVc light on it, that bacteria will find itself in a losing genetic battle, with the UVc invisible rays damaging the bacteria’s DNA faster than the DNA can repair itself. Goodbye bathtub slime. There are several products available on the marketplace that offer a fixed UVc lighting system for keeping HVAC equipment, like cooling coils, clean.

A third area to consider is mobile electronic devices. In today’s “smart hospitals,” doctors and healthcare team members are regularly using cell phones, tablets, or COWS (computers on wheels) as they make their rounds. Studies show that these devices, especially cell phones, are likely to be contaminated.

We would never propose that UV light be the only form of room cleaning, but in an era of increasing antibiotic resistance, it could become an important addition to hospitals’ arsenal.

UV Light That Is Safe for Humans but Bad for Bacteria and Viruses

In the constant battle against the spread of infectious diseases, scientists are continually on the hunt for new weapons that specifically target pathogenic microbes. Now, investigators from the Center for Radiological Research at Columbia University Irving Medical Center (CUIMC) believe they may have found a new, low-cost solution to eradicating airborne viruses in indoor public spaces. The research team found that continuous low doses of far ultraviolet C (far-UVC) light can kill airborne flu viruses without harming human tissues. The findings from the new study—published today in Scientific Reports in an article entitled “Far-UVC Light: A New Tool to Control the Spread of Airborne-Mediated Microbial Diseases”—suggests that use of overhead far-UVC light in hospitals, doctors’ offices, schools, airports, airplanes, and other public spaces could provide a powerful check on seasonal influenza epidemics, as well as influenza pandemics.

Scientists have known for decades that broad-spectrum UVC light, which has a wavelength of between 200 to 400 nanometers (nm), is highly effective at killing bacteria and viruses by destroying the molecular bonds that hold their DNA together. This conventional UV light is routinely used to decontaminate surgical equipment.

“Unfortunately, conventional germicidal UV light is also a human health hazard and can lead to skin cancer and cataracts, which prevents its use in public spaces,” explained senior study investigator David Brenner, Ph.D., director of the Center for Radiological Research and professor at CUIMC.

Interestingly, several years ago, Dr. Brenner and his colleagues hypothesized that a narrow spectrum of ultraviolet light called far-UVC could kill microbes without damaging healthy tissue. Moreover, the researchers demonstrated that far-UVC light was effective at killing MRSA (methicillin-resistant Staphylococcus aureus) bacteria, a common cause of surgical wound infections, but without harming human or mouse skin.

“Far-UVC light has a very limited range and cannot penetrate through the outer dead-cell layer of human skin or the tear layer in the eye, so it’s not a human health hazard,” Dr. Brenner noted. “But because viruses and bacteria are much smaller than human cells, far-UVC light can reach their DNA and kill them.”

Influenza virus spreads from person to person mainly through fine liquid droplets, or aerosols, that become airborne when people with flu cough, sneeze, or talk. The current study was designed to test if far-UVC light could efficiently kill aerosolized influenza virus in the air, in a setting similar to a public space.

In this study, aerosolized H1N1 virus—a common strain of flu virus—was released into a test chamber and exposed to very low doses of 222-nm far-UVC light. A control group of aerosolized virus was not exposed to the UVC light. The far-UVC light efficiently inactivated the flu viruses, with about the same efficiency as conventional germicidal UV light.

“We show for the first time that far-UVC efficiently inactivates airborne aerosolized viruses, with a very low dose of 2 mJ/cm2 of 222-nm light inactivating >95% of aerosolized H1N1 influenza virus,” the authors wrote. “Continuous very low dose-rate far-UVC light in indoor public locations is a promising, safe and inexpensive tool to reduce the spread of airborne-mediated microbial diseases.”

At a price of less than $1000 per lamp—a cost that would surely decrease if the lamps were mass produced—far-UVC lights are relatively inexpensive. This could allow the tool to be utilized in far more places than UV lights are currently being employed, leading to potentially wide sweeping impacts toward diminishing the spread of many infectious diseases.

“If our results are confirmed in other settings, it follows that the use of overhead low-level far-UVC light in public locations would be a safe and efficient method for limiting the transmission and spread of airborne-mediated microbial diseases, such as influenza and tuberculosis,” Dr. Brenner concluded.