Sunlight may kill the coronavirus on surfaces within minutes, according to an unpublished study carried out by US Department of Homeland Security scientists that has not been reviewed by independent experts.

Their results suggest radiation given off by UV rays can damage the virus' genetic material and hamper its ability to replicate on surfaces. There is no evidence UV rays can kill the coronavirus in the body.

The 'evidence' was unveiled at last night's White House press briefing by DHS offical Bill Bryan, who has no scientific background - and triggered a bizarre outburst by Donald Trump.

On the back of the claims, Trump proposed two dangerous new treatments, which included injecting cleaning agents in the body and the use of ultraviolet lights.

Leading scientists today rubbished the use of UV rays as a therapeutic, and begged the public to not expose themselves to harmful radiation, proven to cause skin cancer. Makers of disinfectants rushed out emergency statements warning people not to consume them in any way.

One virologist said that sitting in the sun will not stop any pathogen replicating in an individual patient's internal organs because it cannot penetrate the body.

Others told MailOnline it will not able to make its way 'by some magic' into the lungs to stop the infection in its tracks.

But they agreed that UV rays, which are used by hospitals in the US and UK for decontamination of areas, can kill viruses on surfaces - something which has long been well known.

The DHS 'study', first leaked last week, was carried out by the National Biodefense Analysis and Countermeasures Center. The laboratory in Frederick, Maryland, was set up following the 9/11 terrorist attacks to address biological threats.

A graphic on 'best practices' called for moving activities outside, and noted that heat and humidity hurt the virus. President Donald Trump listens to William Bryan, science and technology advisor to the Department of Homeland Security secretary

The original report was leaked last week (an excerpt of the paper is shown). It suggests the virus cannot survive in high temperatures and humidity

The DHS found that simulated sunlight 'rapidly killed the virus in aerosols,' while without that treatment, 'no significant loss of virus was detected in 60 minutes

The results suggests the coronavirus is most stable in lower humidity than compared to higher temperatures. However, the unpublished documents also state that the results have yet to be proven nor does this not mean the world will see a drop in new cases if they are

WHAT DID THE 'STUDY' FIND? Bryan shared a slide summarizing major findings of the experiment that was carried out at the National Biodefense Analysis and Countermeasures Center in Maryland. 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 70-75F (21-24C). That was based on a 20 per cent humidity on a non-porous surface, which includes things like door handles and stainless steel. But the half-life dropped to six hours when humidity rose to 80 per cent - and to just two minutes when sunlight was added to the equation. When the virus was aerosolized - suspended in the air - the half-life was one hour when the temperature was 70-75F with 20 per cent humidity. In the presence of sunlight, this dropped to just one and a half minutes, according to the slides. Advertisement

'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,' Mr Bryan said. 'We've seen a similar effect with both temperature and humidity as well.'

Bryan shared a slide summarizing major findings of the experiment that was carried out at the National Biodefense Analysis and Countermeasures Center in Maryland.

It showed that the virus's half-life outside the body - the time taken for it to reduce to half its amount -was 18 hours when the temperature was 70-75F (21-24C).

That was based on a 20 per cent humidity on a non-porous surface, which includes things like door handles and stainless steel.

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

When the virus was aerosolized - suspended in the air - the half-life was one hour when the temperature was 70-75F with 20 per cent humidity.

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

The paper itself was not immediately released for review, making it difficult for other experts to comment on how robust its methodology was.

Mr Bryan confirmed scientists had found ultraviolet rays had a potent impact on the pathogen, offering hope that its spread may ease over the summer

He explained increased temperature, humidity and sunlight were detrimental to the killer virus

DO OTHER STUDIES SHOW UV LIGHT CAN KILL THE VIRUS? It has long been known that UV light has a sterilizing effect because the radiation damages the genetic material of viruses and their ability to replicate. Most viruses - such as SARS-CoV-2 - are covered with a thin membrane that is easily broken apart by UV rays. A Columbia University study published in Scientific Reports two years ago showed the light can kill more than 95 per cent of pathogens like the coronavirus. Germicidal UV light is used in hospitals in the US as well as ones run by the NHS in the UK to clean rooms and equipment. The World Health Organization warns that you can catch COVID-19, 'no matter how sunny or hot the weather is'. Cases of the deadly virus have been recorded all over the globe, including in West Africa and the Middle-East. Scientists agree that you are always at risk of catching the virus in the middle of an outbreak because it is indiscriminate and never sleeps. Conventional germicidal UV light kills microbes but also penetrates the skin, raising the risk of various forms of skin cancer as well as cataracts. Advertisement

Professor Ian Jones, a virologist at the University of Reading, England, told MailOnline: 'It's been known for years that UV can lead to a loss of infectivity of many enveloped viruses so this is not really new. However it is good to see it formally confirmed for COVID-19.'

Professor Jones said it cannot be used as a treatment because UV light cannot penetrate the body, adding: 'It's not any sort of therapeutic, more a useful way of sanitizing clothes or surfaces when other options are not available.'

Paul Hunter, a professor of medicine at the University of East Anglia, told MailOnline: 'COVID-19 is predominantly droplet spread so the time for the droplets to get from one person to another is probably seconds rather than minutes.

'Seasonality of such droplet spread infections is probably more to do with people being less cramped together when able to go outside than anything to do with the sterilising effect of UV from sunlight, though it will help a little.

'But this does not mean that UV can in any way be used to treat someone who is infected. The sunlight does not make its way by some magic into the lungs where this virus replicates.'

Dr Irwin Redlener, director of the National Center for Disaster Preparedness at Columbia University, was quick to challenge the presentation.

'Everything that this scientist talked about from Homeland Security was basically incoherent, nonsensical, not really supported by evidence and really quite contrary to a lot of things we do know,' Redlener said on MSNBC.

WHY IS THE DEPARTMENT OF HOMELAND SECURITY DOING SCIENTIFIC TRIALS? Following the 9/11 terror attacks in 2001, the DHS set up a facility dedicated to defending the US against biological threats. The National Biodefense Analysis and Countermeasures Center (NBACC) works in assessing and preparing responses to acts of terror. Its 150 staff work with Government agencies including the FBI and CIA, conducting biological research in their lab in Fredrick, Maryland. But when the US declared COVID-19 a national emergency, the team became pivoted its research efforts to tackling the crisis. Advertisement

A key question will be what the intensity and wavelength of the UV light used in the experiment was, scientists say.

For instance, it may have been under a setting that did not accurately mimic natural light conditions in summer.

Dr Benjamin Neuman, chair of biological sciences, Texas A&M University-Texarkana, said: 'It would be good to know how the test was done.

'Not that it would be done badly, just that there are several different ways to count viruses, depending on what aspect you are interested in studying.'

Scientists across the world also disagree over whether the deadly virus really will ease off in the warmer weather. Infectious disease experts believe transmission rates will drop off in the summer, like seen for flu.

But a Chinese study earlier this month dashed hopes that the pandemic will start to die down in the northern hemisphere after finding no evidence that the infection rate dropped in areas with more sunlight.

Speaking at the White House press conference last night, Mr Bryan concluded that summer-like conditions 'will create an environment (where) transmission can be decreased'.

He added, though, reduced spread did not mean the pathogen would be eliminated entirely and social distancing guidelines cannot be fully lifted.

A separate study looked at the cases in 100 Chinese cities last month and found transmission rates fell as the weather grew warmer or more humid. Each blue dot signifies the average number of transmissions per infected person at a given humidity level, meaning that on days when humidity was 100%, the transmission rate hovered mostly below two per infected person

As temperatures rose in 100 Chinese cities, the average number of people who those infected with coronavirus passed it to fell from 2.5 to less than 1.5, Chinese researchers found

WHO IS BILL BRYAN? William Bryan is an army veteran with 17 years of active military service and three years in the Virginia National Guard - but he is not a scientist William Bryan is an army veteran with 17 years of active military service and three years in the Virginia National Guard - but he is not a scientist. He was appointed science and technology advisor to the Department of Homeland Security Secretary in May 30, 2017. Bryan was given the job on the back of a three-year stint as president of ValueBridge International's Energy Group, a sustainable energy firm. Before that, he held a number of leadership roles at the Department of Energy and Department of Defense. However, his years as a civil servant did not come without controversy. A New York Times article in 2018 reported that US and Ukrainian officials had expressed concern about whether Mr Bryan had been working for a Ukrainian company seen as aligned with a prominent oligarch while working for the US Government. The Times reported that concerns were heightened when Mr Bryan later joined ValueBridge and pursued business with the company. Mr Bryan told the newspaper at the time he 'never made a dime off any of the people I knew from the Ukraine, deliberately, because I didn't want to violate any of the ethics rules.' During the nomination process to become science and technology advisor to the DHS, he said: 'I believe the mission of (Science and Technology) is to deliver results,' Bryan testified in the Senate during his nomination process. 'To do this, we must enable effective, efficient, and secure operations across all homeland security missions by applying timely scientific, engineering and innovative solutions through research, design, test and evaluation, and acquisition support.' Advertisement

Bryan said: 'It would be irresponsible for us to say that we feel that the summer is just going to totally kill the virus.'

But US health authorities believe that even if COVID-19 cases slow over summer, the rate of infection is likely to increase again as winter approaches.

Transmission of flu and the common cold both drop in the summer, partly because people spend less time indoors and in close contact with others.

One Chinese study earlier this month dashed hopes that warmer weather will halt the pandemic in the northern hemisphere.

Fudan University researchers analysed the spread of coronavirus in 224 Chinese cities — including 17 in Hubei province, where the outbreak began.

The study then compared this information with daily weather data over the period between January and early March 2020.

The team found there was no significant association between either the temperature or the levels of UV exposure from sunlight and the total infection rate.

But some scientific work has also agreed that the virus fares better in cold and dry weather than it does in hot and humid conditions.

Studies from both Beihang and Tsinghua Universities found the transmission rate of COVID-19 in China fell in as the temperature grew warmer.

And the lower rate of spread in southern hemisphere countries - which were hit by outbreaks in their summer - offers proof of the theory.

Australia, for example, has had just under 7,000 confirmed cases and 77 deaths - well below many northern hemisphere nations.

The reasons are thought to include that respiratory droplets can remain airborne for longer in colder weather.

Studies also show that viruses degrade more quickly on hotter surfaces because a protective layer of fat that envelops them dries out faster.

It has long been known that UV light has a sterilizing effect because the radiation damages the genetic material of viruses and their ability to replicate.

Most viruses - such as SARS-CoV-2 - are covered with a thin membrane that is easily broken apart by UV rays.