US Agency Says Sunlight Destroys Coronavirus Quickly

WASHINGTON, United States (AFP) – The new coronavirus is quickly destroyed by sunlight, according to a new study announced by a senior US official on Thursday, offering hope that its spread may ease over the summer.

William Bryan, science and technology advisor to the secretary of the Department of Homeland Security, told reporters at the White House that government scientists had found ultraviolet rays had a potent impact.

“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,” he said.

“We’ve seen a similar effect with both temperature and humidity as well, where increasing the temperature and humidity or both is generally less favourable to the virus.”

He then showed a slide summarizing the results of the experiment that were carried out at National Biodefense Analysis and Countermeasures Center.

It showed that the virus’s half-life — the time taken for it to reduce to half its amount — was 18 hours when the temperature was 70 to 75 degrees Fahrenheit (21 to 24 degrees Celsius) with 20 per cent humidity on a non-porous surface.

This includes surfaces like door handles and stainless steel.

But the half-life dropped to six hours when humidity rose to 80 per cent — and just two minutes when sunlight was added to the equation.

When the virus was aerosolized — meaning suspended in the air — the half-life was one hour when the temperature was 70 to 75 degrees with 20 percent humidity.

In the presence of sunlight, this dropped to just one and a half minutes.

Bryan concluded that summer-like conditions “will create an environment with a transmission can be decreased.”

But he cautioned that reduced spread did not mean the pathogen would be eliminated entirely and social distancing guidelines cannot be fully lifted.

“It would be irresponsible for us to say that we feel that the summer is just going to totally kill the virus and then if it’s a free-for-all and that people ignore those guides,” he said.


  1. Sunlight, particularly UV rays, will kill almost anything if it is left exposed long enough. All viruses and bacteria are destroyed by sunlight, although the time for this to happen varies. This does not mean that once exposed to sunlight they will be destroyed. The fact of the matter is that although sunlight along with other conditions reduces the half life of the coronavirus, its ability to infect still exists and therefore requires the same precautionary measures. The simple failure to observe social distancing will mean absolutely nothing in a person to person transmission. These combined ‘perfect’ conditions, humidity, temperature, and UV rays, are controlled environment examples, and seldom occur frequently or regularly in the real world. Wash your hands, use an alcohol based hand sanitizer, and wear a mask.

  2. I have never seen such bull**** like this. If COVID19 was killed by sunlight like these people are suggesting then, we in the tropics should have nothing to fear but this is not so.

  3. Its logical. Yall forget Nature is boss??

    The SUN purifies and cleanses everything on the earth. It brings life and takes life. It brings the fire to purify water.

    To the sceptics….Its physics, basic physics:
    You dont have to live in the UK or Canada or NY to have personal experience of catching the flu every winter without fail. So sceptics you are still not excused because you have relatives abroad even if you never travel out of SLU during a foreign winter.

    Its obvious. It’s not spreading in st Lucia especially in our dry season ONCE WE SOCIAL DISTANCE AND MASK UP and WE JUST NEED TO PROTECT OUR BORDERS by testing to get the economy rolling. It will only be for a year or two until a global vacine is ready.

    • John public they are not saying the sunlight can kill the virus when it’s in your body. The virus cannot survive for long period on surfaces or in the air in the sunlight, just like the Aids virus. Aids virus cannot survive outside of the body in sunlight or no sunlight.

  4. Bon dieu!! There are the “skeptics” and the “bwa-bwa” people … and those who make perfect sense. I go with the “perfect sense” people @ Eye In the Sky” @Heat Purge It @Really. You all understand!!

  5. Some people only read the headlines, and not the content … the latter is where all the information lies.

Comments are closed.