A unique type of UV light that's safe for humans may be an effective, low-cost solution to eliminating airborne viruses, including flu, in indoor public spaces.
Researchers at Columbia University found that continuous overhead doses of far ultraviolet C (far-UVC) light kills flu viruses. They suggest the light could be used in schools, hospitals, doctors' offices, airports, airplanes, and other public spaces as a powerful weapon against seasonal flu epidemics as well as influenza pandemics.
Scientists have known for decades that broad-spectrum UVC light is very effective at killing bacteria and viruses by destroying the molecular bonds that hold their DNA together. It's 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," said study leader David J. Brenner.
Brenner and his colleagues hypothesized that a narrow spectrum of ultraviolet light called far-UVC could kill microbes without damaging healthy tissue. "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," he said.
"But because viruses and bacteria are much smaller than human cells, far-UVC light can reach their DNA and kill them," he continued.
Since 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 new 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.
Researchers aerosolized H1N1 virus — a common strain of flu virus — then released it into a test chamber and exposed it 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 and was about as efficient as conventional germicidal UV light.
"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," said Brenner.
Currently, lamps are less than $1,000 each, which is relatively inexpensive, but the cost would probably decrease if they were mass produced. "And unlike flu vaccines, far-UVC is likely to be effective against all airborne microbes, even newly emerging strains," Brenner said.
The study was published online today in Scientific Reports.
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