Thus installed in the ceilings of certain offices are ultraviolet C lamps which kill germs. Above the place where people circulate, the lamps emit ultraviolet light which, over time, can kill bacteria and fungi and break down viruses.
It has become fairly standard technology in hospitals, clinics and other places where germs could be in the air. They only work if there is enough air to carry the germs to the level of the lamps and then bring that disinfected air back to where people breathe.
And they have to stay high because to kill germs, the lamps must emit so much UV light that it would be irritating to people, especially their eyes.
“When we use it for surface decontamination, we make sure that nobody is in the room,” Milton said in an interview with CNN. “And when we use it to decontaminate the air in the upper room, we make sure there are very few in the room so it doesn’t fall into your eyes.” “
Milton said he was stunned when he heard President Trump ask him to use such light to decontaminate people. “Suppose we hit the body with a huge light, whether it’s ultraviolet or just very strong,” Trump said during the White House briefing on Thursday.
UV light can damage the body
The virus lives inside the body where light cannot reach, and spreads mainly in small droplets that spray when infected people cough, sneeze, or speak.
“Irradiating the outside of them with UV light is not going to do anything for the virus inside despite what Donald Trump says about putting a UV inside someone,” said Professor Milton. environmental health. ” It will not work. “
Ultraviolet light is part of the electromagnetic spectrum emitted by the sun. UVC rays are absorbed by atmospheric ozone, but UVA and UVB rays reach the Earth’s surface. Both UVA and UVB are important for human health.
Small amounts of UV are essential for the production of vitamin D in humans, but overexposure can cause acute and chronic effects on the skin, eyes and immune system.
Two factors are necessary for ultraviolet light to destroy a virus: intensity and time. But if the light is intense enough to break down a virus in a short period of time, it’s going to be dangerous for people, said Milton. UVA and UVB light damages the skin. UVC light is safer for the skin, but it will damage sensitive tissues such as the eyes.
“It has been used for some time in surface decontamination by bringing very bright lights into, say, the hospital room between patients to perform rapid surface decontamination,” said Milton. “But that means the lights are so bright that you can’t have people in the room because it will hurt their eyes. “
This has not stopped an industry from emerging and offering for sale ultraviolet decontamination lamps for offices and even homes. Stores offer ultraviolet wands for sale for personal use, promising that they will kill germs immediately.
They will not do so, says the Illuminating Engineering Society, a non-profit industry group.
“Ultraviolet or other” ultraviolet disinfectant wands “for residential use – as they are insufficiently proven and unregulated – may pose a security risk and are unlikely to provide the protection expected,” the group said in a statement. sent to CNN.
The group says lamps installed in ceilings at least 7 feet high can safely decontaminate the air, but also warns that light can irritate people’s eyes. “UV germicides are also applied for the disinfection of certain personal protective equipment (PPE) for limited reuse during the pandemic,” added the group.
Some marketers imply that installing UV lights can kill a virus after it leaves an infected person’s body and before it gets to someone else, but lights don’t work if people are quick and infected would still spread the virus, Milton said.
“You can sterilize the outside of them, but they spread the virus and breathe and talk while they are at work,” he said. “They’re going to bring it right after the UV curtain they cross on their way to the office. “
At the White House briefing, Trump also questioned the possibility of using disinfectants inside people to kill the virus. His comments intrigued and outraged doctors and several industry and medical groups, who immediately warned that people should never ingest bleach or other disinfectants.
And the World Health Organization has warned against any attempt to use ultraviolet light to kill the virus.
“UV lamps should not be used to sterilize hands or other areas of the skin as UV rays can cause skin irritation,” says the WHO.
“You can catch COVID-19 regardless of the sunny or hot weather. Countries with hot weather have reported cases of COVID-19, “added WHO.