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* Click here for some background in case you missed it last weekend. Here’s William Bryan, the temporary head of science and technology at the Department of Homeland Security, speaking at yesterday’s White House briefing…
First, let me tell you what a half-life is. We don’t measure the virus as far as how long will it live on a surface. We have to measure the decay of the virus in terms of its half-life because we don’t know certain-… That has a bearing on how long the virus is going to be alive and active. So, we measure it in half-life because half-life doesn’t change.
So, if you look at an 18 hour half-life, what you’re basically saying is that every 18 hours the life of the virus is cut in half. So, if you start with 1000 particles of the virus, in 18 hours you’re down to 500, and 18 hours after that you’re down to 250 and so on and so forth. […]
So, the virus is dying at a much more rapid pace just from exposure to higher temperatures and just from exposure to humidity. If you look at the fourth line, you inject the sunlight into that, you inject UV rays into that, the same effects on line two as 70 to 75 degrees with 80% humidity on the surface and look at line four but now you inject the sun, the half-life goes from six hours to two minutes. That’s how much of an impact UV rays has on the virus. […]
So, in summary, within the conditions we’ve tested today, the virus in droplets of saliva survives best in indoors and dry conditions. … look at the aerosol as you breathe it, you put it in a room, 70 to 75 degrees, 20% humidity, low humidity. Half-life is about an hour, but you get outside and it cuts down to a minute and a half. Very significant difference when it gets hit with UV rays. […]
(I)ncreasing the temperature and humidity of potentially contaminated indoor spaces appears to reduce the stability of the virus, and extra care may be warranted for dry environments that do not have exposure to solar light.
Translation: Open the windows and turn up the heat in congregate settings like nursing homes, retail establishments, offices, etc. And even if turns out this doesn’t work, it’s not going to do any harm. Fresh air is fresh air.
* More on indoor humidity…
Several studies support the idea that indoor humidity plays a role in seasonal disease transmission. When someone coughs or sneezes, they release tiny droplets into the air (if they’re sick, these droplets will contain virus). The bigger droplets typically fall before they get very far, but the tiniest droplets, called droplet nuclei, can go much farther. In humid conditions, these tiny droplets don’t evaporate as much, so they drop down more quickly than they would in dry conditions. Virus-containing droplets that travel farther are more likely to infect a new host.
* Outside might be a different thing, however…
Bryan warned it would be “irresponsible” to say the warmer summer months will eliminate the virus. But he said that time period would provide an “opportunity to get ahead” of the pandemic.
* Bryan also said this, by the way…
We’re also testing disinfectants readily available. We’ve tested bleach, we’ve 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 bring it on and leaving it go. You rub it and it goes away even faster.
posted by Rich Miller
Friday, Apr 24, 20 @ 2:08 pm
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Trump just trademarked bleach-o-matic, a machine that lets coronavirus sufferers bleach their lungs at home. It supposedly has free replacement wands for application and tubes for fluid extraction. But numbing agent for the choking reflex will be sold separately.
Comment by Grandson of Man Friday, Apr 24, 20 @ 2:23 pm
OK, let’s stick to the topic at hand. It’s OK to have some fun, but this is a serious topic.
Comment by Rich Miller Friday, Apr 24, 20 @ 2:26 pm
0Now I would be more science nerd curious how much humidity has to do with transmission due to the air being denser and what impact that has on the cooties flying out of someones’ nose or mouth.
My guess isn’t much, but it seems like that could be mathematically modeled. Again would just be curious; don’t see that as a solution.
But man, the other impacts on most places by turning up the heat and the humidity in a modern office (or even a current grocery store) may not be trivial. Also, nothing like a warm office to either convince someone who has a fever that they are just hot due to the building being hot or make someone think they have a fever when they don’t.
Comment by OneMan Friday, Apr 24, 20 @ 2:27 pm
Rich - I understand the intention of the post, but I’d hesitate encouraging folks to “turn up the heat.” Hydration and fluid retention are big issues for many of these individuals.
Comment by Patient safety Friday, Apr 24, 20 @ 2:27 pm
I think most people knew or suspected all of that could help prevent people getting infected (NOT as a treatment for infected people). UV light in particular has been used for a while to help disinfect rooms. It’s always good to get officials studies to make sure this virus reacts like other viruses though.
Comment by Perrid Friday, Apr 24, 20 @ 2:34 pm
This might be a small, ever so slight reason as to why infection rates and numbers seem higher in cold climates and places where folks are indoors in say the winter when forced air heat dries things out.
So not a scientist says COIVD is going to be here all spring and summer and fall and winter - But the transmission of the virus person to person might be less than in the late winter or spring.
Comment by Cool Papa Bell Friday, Apr 24, 20 @ 2:58 pm
For those without humidifiers, boil a pot of water on the stove if you feel safe doing that. Also, allowing fresh air in may act to lower the indoor concentration by dilution (air comes in, air with corona goes out hopefully). Very dry mucous membranes in the nose and throat are also more susceptible to the virus sticking to the membranes and causing infection (https://health.clevelandclinic.org/can-best-combat-effects-dry-winter-air/)
Comment by revvedup Friday, Apr 24, 20 @ 3:01 pm
I am puzzled by the example used to explain half life. Any virus deposited on a surface at the same time would degrade. So all of the virus present in droplets would have a half life. It doesn’t mean that half the viruses are gone and half remain. It means that all the virus deposited in droplets at a specific time are degrading. If I am correct then William Bryan the temporary head of technology and science for Homeland security either doesn’t understand what half life is or he chose a poor example to try and explain it. This should create doubt regarding other information in his presentation. I wonder if he was appointed by the man who asked if bleach could be injected into our bodies to cure the virus.
Comment by Almost retired Friday, Apr 24, 20 @ 3:06 pm
hydrate - drink water. put a pan of water on your radiator if you have that kind of heat, or use a hanging device for water, or buy even a tiny cool mist device for your bedroom. there are even ceramic water holders that are specifically designed to use for humidity.
Comment by amalia Friday, Apr 24, 20 @ 4:02 pm
What? No mention of my favorite, ethanol?
Comment by Da Big Bad Wolf Friday, Apr 24, 20 @ 4:23 pm