Washington D.C. [US]: The solar light appears to have a “powerful effect” on killing the deadly coronavirus, which has infected over 2 million people worldwide, according to a senior US official.
“Our most striking observation to date is the powerful effect that solar light appears to have on killing the virus — both surfaces and in the air,” said William Bryan, Senior Official Performing the Duties of the Under Secretary for Science and Technology (DHS) at a White House briefing here.
“We’ve seen a similar effect with both temperature and humidity as well, where increasing the temperature and humidity or both is generally less favorable to the virus.” According to the slides shown at the briefing, the half-life of the virus, which is 18 hours at 70-75 degree Fahrenheit and 20 per cent humidity on a non-porous surface including door handles and stainless steel, decreases to 6 hours when humidity is increased to 80 per cent.
“And if you look at the — as the temperature increases, as the humidity increases, with no sun involved, you can see how drastically the half-life goes down on that virus. So the virus is dying at a much more rapid pace, just from exposure to higher temperatures and just from exposure to humidity,” said Bryan.
The half-life further decreases to two minutes when sunlight is added to the equation. “That’s how much of an impact UV rays has on the virus,” the US official said.
“When you look at that chart, look at the aerosol as you breathe it; you put it in a room, 70 to 75 degrees, 20 percent humidity, low humidity, it lasts — the half-life is about an hour. But you get outside, and it cuts down to a minute and a half. A very significant difference when it gets hit with UV rays,” he explained.
Bryan cautioned that “extra care” may be warranted for dry environments that do not have exposure to solar light.
“We are also testing disinfectants readily available. We have tested bleach, we have tested isopropyl alcohol on the virus, specifically in saliva or in respiratory fluids. And I can tell you that bleach will kill the virus in five minutes; isopropyl alcohol will kill the virus in 30 seconds, and that’s with no manipulation, no rubbing — just spraying it on and letting it go,” he said.
Bryan, however, added: “This is not the end of our work as we continue to characterize this virus and integrate our findings into practical applications to mitigate exposure and transmission.”