Study: Sunlight Levels Are Inversely Correlated with Virus Infections

Conclusions

These results are consistent with epidemiological findings that sunlight levels are inversely correlated with influenza transmission, and they can be used to better understand the potential for the virus to spread under varied environmental conditions.

An excellent article showing developments in commercial devices using UV to kill viruses came in February 2018 with ‘This UV Lamp Could Prevent the Flu Virus From Spreading in Public Places’ (Amanda MacMillan). [2]

MacMillan wrote:

“Researchers have developed an ultraviolet (UV) lamp that kills the influenza virus but isn’t harmful to human skin or eyes, according to a new study in Scientific Reports. They hope the technology can be commercialized and marketed to prevent the spread of seasonal flu in public places, such as schools, hospitals, and airports.

“We’ve known for a century that UV light is extremely efficient at killing microbes, bacteria, and viruses,” says study leader David Brenner, director of the Center for Radiological Research at Columbia University Irving Medical Center. For that reason, UV devices are often used for sterilization — for medical equipment in hospitals, for example, or drinking water for backcountry campers.”

Brenner explained that the problem with conventional germicidal lamps was that prolonged exposure to humans could cause skin cancer and cataracts in the eyes. Brenner says, “You can sterilize a hospital room, but not when anyone’s inside.”

See video:

To get round this problem the Columbia team came up with a solution. They used light on the far end of the UV-C spectrum, known as far-UVC, which has very short wavelengths. What they found was that far-UVC can penetrate and destroy microscopic bacteria and viruses, but can’t travel through the protective outer layers of human skin or eyes.

Brenner and his colleagues proved that UVC light can effectively kill airborne influenza. In their new study, aerosolized particles of the H1N1 seasonal flu virus were released into a test chamber and exposed to very low doses of far-UVC light. Their ‘softer’ light treatment was shown to be as effective as conventional germicidal UV light.

As the COVID19 pandemic drives interest in a whole range of personal health safeguards from clinical masks, sanitizer gels, more hand washing, etc. consumers are looking to invest in products which use safe UV to sterilize their homes and businesses.

shoplightsanitizer.com claim their product will “sterilize everything within reach” and that “20 seconds of light is all that is needed.”

According to Wikipedia:

“In 1878, Arthur Downes and Thomas P. Blunt published a paper describing the sterilization of bacteria exposed to short-wavelength light.^[3] UV has been a known mutagen at the cellular level for over 100 years.

Air disinfection

UVGI can be used to disinfect air with prolonged exposure. Disinfection is a function of UV intensity and time. For this reason, it is not as effective on moving air, or when the lamp is perpendicular to the flow, as exposure times are dramatically reduced.

ASHRAE covers UVGI and its applications in indoor air quality and building maintenance in “Ultraviolet Lamp Systems”, Chapter 16 of its 2008 Handbook, HVAC Systems and Equipment. Its 2011 Handbook, HVAC Applications, covers “Ultraviolet air and surface treatment” in Chapter 60.

Laboratory hygiene

UVGI is often used to disinfect equipment such as safety goggles, instruments, pipettors, and other devices. Lab personnel also disinfect glassware and plasticware this way. Microbiology laboratories use UVGI to disinfect surfaces inside biological safety cabinets (“hoods”) between uses.”