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Sunlight and bleach might kill the coronavirus on a park bench, but they can be harmful to the body

U.S. President Donald Trump speaks during the daily briefing of the coronavirus task force at the White House on April 22, 2020, in Washington, D.C. (Photo by Drew Angerer/Getty Images)

(CNN) — Sunlight and bleach can both kill the new coronavirus, a federal official told the daily White House briefing Thursday. But President Trump turned what should have been a simple scientific summary into a puzzling stream of dangerous ideas about somehow streaming light into the body and suggestions about injecting disinfectants.

Here’s what was said, and what science really tells us about safely killing viruses.

Bill Bryan, a senior official at the US Department of Homeland Security, said studies on the virus showed bleach kills coronavirus in about five minutes, and isopropyl alcohol destroys it even faster. Tests showed the virus in droplets of saliva survives best indoors and in dry conditions.

“The virus dies the quickest in the presence of direct sunlight under these conditions,” he said.

Bryan, who is not a scientist, said a U.S. Army biological lab outside Washington, DC, had been testing the virus.

“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. Temperature and humidity also affect how long the virus survives, Bryan said.

Vice President Mike Pence called Bryan’s presentation “encouraging news about the impact of that heat and sunlight have on the coronavirus, which will increase the confidence that we feel about the coming summer.”

Bryan called it “another weapon in the fight that we can add to it and in the summer.” But he added: “It would be irresponsible for us to say that we feel the summer will totally kill the virus. We have an opportunity though to get ahead with what we know now and factor that into the decision-making.”

Earlier this month, members of an influential National Academy of Sciences committee told the White House in a letter that it doesn’t look like the coronavirus will go away once the weather warms up, writing: “There is some evidence to suggest that [coronavirus] may transmit less efficiently in environments with higher ambient temperature and humidity; however, given the lack of host immunity globally, this reduction in transmission efficiency may not lead to a significant reduction in disease spread without the concomitant adoption of major public health interventions.” The panel noted that the virus continued to spread in countries experiencing warm weather.

But how the virus reacts in a lab is not necessarily relevant to how it is transmitted. It can be transmitted on very small particles of saliva or mucus that spray out from people’s mouths when they talk or cough, or from noses when they sneeze. But the particles do not linger in the air long for long, and drop to the ground.

The danger of catching the virus comes from being in close contact with someone who is infected and emitting particles from the nose and mouth, or touching something that virus-laden particles have landed on.

The findings Bryan shared are not surprising. Scientists have long known that chemicals such as bleach can kill viruses, including coronaviruses, as can ultraviolet light.

What was perhaps surprising during Thursday’s briefing was President Trump’s take on Bryan’s comments.

“Suppose that we hit the body with a tremendous, whether it’s ultraviolet or just very powerful light and I think you said that it hasn’t been checked and you’re going to test it,” Trump told Bryan. “Suppose you can bring the light inside the body.”

It was not immediately clear how Trump would propose bringing light into the body.

“And then I see the disinfectant where it knocks it out in one minute. Is there a way we can do something like that by injection inside or almost a cleaning … it would be interesting to check that,” Trump added.

Trump’s statement echo myths and rumors that got so rampant on the internet and in social media that the World Health Organization posted a mythbusters pages to debunk them.

“Exposing yourself to the sun or to temperatures higher than 25C degrees DOES NOT prevent the coronavirus disease,” WHO says on its website. “You can catch COVID-19, no matter how sunny or hot the weather is. Countries with hot weather have reported cases of COVID-19,” it adds.

It also warns specifically against using ultraviolet lamps, including tanning lamps, to try to kill virus. “UV lamps should not be used to sterilize hands or other areas of skin as UV radiation can cause skin irritation,” WHO cautions.

Ultraviolet light damage skin lead to cancer if people get enough of it.

And chlorine bleach it toxic. It can and does kill people who drink it. The US Food and Drug Administration regularly warns the public against drinking bleach, or even inhaling fumes from bleach. It’s also irritating to skin.

Last week, the US Centers for Disease Control and Prevention said calls about poisonings with cleaners and disinfectants had increased more than 20% in the first three months of 2020 — as coronavirus cleaning increased — than from the same period a year earlier. Among cleaners, bleaches accounted for the largest percentage increase in calls from 2019 to 2020.

The CDC recommends using soap and water or bleach to kill the virus. Rubbing alcohol that’s at least 70% alcohol will also kill it on surfaces; 60% for your hands.