Some backing for high temps, humidity, and sunlight as the enemy of the virus - Printable Version
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Some backing for high temps, humidity, and sunlight as the enemy of the virus - JustAnotherFan - 04-21-2020
Can we convince people to leave their air conditioning to spend their days under the sun in the summer heat? Time to bring back the open field hospitals.
"Preliminary results from government lab experiments show that the coronavirus does not survive long in high temperatures and high humidity, and is quickly destroyed by sunlight, providing evidence from controlled tests of what scientists believed — but had not yet proved — to be true."
https://news.yahoo.com/sunlight-destroys-coronavirus-very-quickly-new-government-tests-find-but-experts-say-pandemic-could-still-last-through-summer-200745675.html
RE: Some backing for high temps, humidity, and sunlight as the enemy of the virus - OutsiderFan - 04-21-2020
OK, now I'm confused:
https://www.newsweek.com/coronavirus-heat-kill-virus-1498074
RE: Some backing for high temps, humidity, and sunlight as the enemy of the virus - cardcrimson - 04-21-2020
(04-21-2020, 05:03 AM)JustAnotherFan Wrote: Can we convince people to leave their air conditioning to spend their days under the sun in the summer heat? Time to bring back the open field hospitals.
"Preliminary results from government lab experiments show that the coronavirus does not survive long in high temperatures and high humidity, and is quickly destroyed by sunlight, providing evidence from controlled tests of what scientists believed — but had not yet proved — to be true."
https://news.yahoo.com/sunlight-destroys-coronavirus-very-quickly-new-government-tests-find-but-experts-say-pandemic-could-still-last-through-summer-200745675.html
Time to reopen the pools. Chlorine, high humidity, sunlight, heat.
Just a hopeful thought, really. But I'm hoping. . .
RE: Some backing for high temps, humidity, and sunlight as the enemy of the virus - M T - 04-22-2020
(04-21-2020, 06:12 AM)OutsiderFan Wrote: OK, now I'm confused:
https://www.newsweek.com/coronavirus-heat-kill-virus-1498074
Confusion is what one gets when one listens to the media, and then applies logic to what you're told. From the Yahoo coverage of the unseen government lab report, we don't know how quick "quickly" is, how high "high temperature" is, or how destroyed "destroyed" is.
The Newsweek article has a link to the actual report. First thing I notice is that they are actually working to a standard. About time. And they are reducing the levels of virus by 6 orders of magnitude, so a million-fold. AND they are reporting how long to get to that point, not some point arbitrarily short of that point.
Remember the report in early March that said something about 3 days on plastic and 24 hours on cardboard? What it really said was to get a TWO orders of magnitude reduction in virus, you needed to wait 4 days on plastic and 48 hours on cardboard. (Their criteria was from some arbitrary starting concentration of virus, and deciding it was enough when their test wasn't sensitive enough to detect any. For a few tests, that was a bit over 3 orders of magnitude, but IIRC most tests were a reduction of two orders of magnitude.)
Then it was reported as "The virus is still alive after 3 days on plastic and 1 day on cardboard". They did show that, as well as showing the virus was still active after 1 day on plastic and 6 hours on cardboard. It wasn't until 4 days had elapsed that the virus was below their instrument's sensitivity on plastic. 2 days on cardboard.
This new study is setting a much higher bar, a million-fold reduction in viral levels. If you want to be really sure you don't have much virus left, to get from a 2-log drop to a 6-log drop, triple the time involved. One could expect the virus to reach a 6-order of magnitude drop on plastic around day 12 (3 * 4), based on the earlier result. For cardboard, it would be about 6 (= 3*2) days. That's at room temperature & normal humidity (40-60% RH, I believe).
The report referenced by Newsweek reported on times that it took to achieve this level of reduction at temperatures of 30min@56C, 60min@60C, and 15min@92 degrees C. The first two were >5-log reductions; the last was >6-log. These kinds of times are consistent with what was reported in 2009 for coronaviruses.
Oh, by the way, regarding humidity and viruses: The role humidity plays for inactivating viruses seems to be all over the map. Different effects at different temperatures, etc.
RE: Some backing for high temps, humidity, and sunlight as the enemy of the virus - JustAnotherFan - 04-22-2020
(04-21-2020, 06:12 AM)OutsiderFan Wrote: OK, now I'm confused:
https://www.newsweek.com/coronavirus-heat-kill-virus-1498074
LOL, you Californians are so soft. Give me the 150 degree summer days!
(04-21-2020, 08:22 AM)cardcrimson Wrote:(04-21-2020, 05:03 AM)JustAnotherFan Wrote: Can we convince people to leave their air conditioning to spend their days under the sun in the summer heat? Time to bring back the open field hospitals.
"Preliminary results from government lab experiments show that the coronavirus does not survive long in high temperatures and high humidity, and is quickly destroyed by sunlight, providing evidence from controlled tests of what scientists believed — but had not yet proved — to be true."
https://news.yahoo.com/sunlight-destroys-coronavirus-very-quickly-new-government-tests-find-but-experts-say-pandemic-could-still-last-through-summer-200745675.html
Time to reopen the pools. Chlorine, high humidity, sunlight, heat.
Just a hopeful thought, really. But I'm hoping. . .
I've wondered what sick people spitting out pool water that others will have go up their noses will mean for the spread of the virus. Can't be good.
RE: Some backing for high temps, humidity, and sunlight as the enemy of the virus - cardcrimson - 04-22-2020
(04-22-2020, 05:25 AM)JustAnotherFan Wrote:(04-21-2020, 06:12 AM)OutsiderFan Wrote: OK, now I'm confused:
https://www.newsweek.com/coronavirus-heat-kill-virus-1498074
LOL, you Californians are so soft. Give me the 150 degree summer days!
(04-21-2020, 08:22 AM)cardcrimson Wrote:(04-21-2020, 05:03 AM)JustAnotherFan Wrote: Can we convince people to leave their air conditioning to spend their days under the sun in the summer heat? Time to bring back the open field hospitals.
"Preliminary results from government lab experiments show that the coronavirus does not survive long in high temperatures and high humidity, and is quickly destroyed by sunlight, providing evidence from controlled tests of what scientists believed — but had not yet proved — to be true."
https://news.yahoo.com/sunlight-destroys-coronavirus-very-quickly-new-government-tests-find-but-experts-say-pandemic-could-still-last-through-summer-200745675.html
Time to reopen the pools. Chlorine, high humidity, sunlight, heat.
Just a hopeful thought, really. But I'm hoping. . .
I've wondered what sick people spitting out pool water that others will have go up their noses will mean for the spread of the virus. Can't be good.
According to several studies posted previously, chlorine and bromine, the chemicals typically used to keep pools clean, inactivate coronaviruses. Pools, especially community ones, have to keep their levels way up to inactivate all sorts of nasty stuff--urine, feces (including e coli), cold and flu, etc. and are tested by the local health agencies quite often.
RE: Some backing for high temps, humidity, and sunlight as the enemy of the virus - OutsiderFan - 04-22-2020
My friend who has the husband who works as Nurse at Long Term Care facility, was so concerned about the amount of bleach required to wash his clothes, she decided to use the pool shock for her pool in the washing machine to save on bleach.
RE: Some backing for high temps, humidity, and sunlight as the enemy of the virus - BostonCard - 04-22-2020
Good points MT. I think the challenge is knowing how low is low enough. To really know, you would have to know the IC50 (concentration that results in a 50% probability of infection), but of course a lot of that has to do with behavior. Like, does the individual touch their face after touching the infected surface. How prevalent is hand washing? Etc.
The problem is that we don't know how many log order reduction in viral particles is required to reduce the infectiousness significantly.
BC
RE: Some backing for high temps, humidity, and sunlight as the enemy of the virus - M T - 05-14-2020
I still haven't seen even a preprint of the sunlight (etc) study that was highlighted in an April 23 White House press briefing. Has anyone else?
I remember being furious at the idiocy of presenting half life information to the 144-character public. This was just begging to get misunderstood. Indeed, a friend later said about their cloth mask that they could just put it on their car dashboard for 3 minutes in the sunlight. Amongst the things I informed her of was that the windshield filters out the UV that probably does most of the inactivation. And, oh yes, the time of day matters. And 3 minutes is nowhere near long enough.
There were some posters presented that I haven't seen in an easy-to-read format. Indeed, I tried some Google searches and didn't find the contents of the posters, so I'm going to put them here.
Quote:Increased temperature, humidity, and sunlight
are detrimental to SARS-CoV-2 in saliva droplets
on surfaces and in the air
CONDITION Temp Humidity Solar HALF LIFE Surface 70-75 F 20% None 18 hours Surface 70-75 F 80% None 6 hours Surface 95 F 80% None 1 hour Surface 70-75 F 80% Summer 2 minutes Aerosol 70-75 F 20% None ~60 minutes Aerosol 70-75 F 20% Summer ~1.5 minutes
Hmmmm... I wonder why they didn't put up 50-55 F and 30-35 F?
From a scientific viewpoint, this chart is quite simplistic. Only 2 points are listed on each of the 3 variables. I guess you're supposed to believe these are monotonic at least (which other studies have shown isn't true for humidity). They also showed half-life times and didn't show something like to get rid of 99.9% of the virus particles, you need 10 half-lives, and that leaves alive a billion particles from a cough.
Then there's the matter of summer sunlight. Noon? Latitude? Altitude? It all makes a difference. The above half-life of 2 minutes suggests a 1 log (10x) reduction inn 6.6 minutes. That's a good bit less than the >= 20 minutes (to 100 minutes) for a different virus in this earlier study, which gives some indication of how the duration for a 1 log reduction at different places at different times.
If a surface is at 30 degrees from horizontal (for noon sun) it will get cos(30) = 87% as much sunlight (so to get as much, it has to go (100-87)/87 longer = 15% longer, so 2.3 minutes.
If at 45 degrees, 71%, so 29/71 =41% longer, or 2.82 minutes.
If at 60 degrees, 50% so 50/50 = 100% longer or 4 minutes
90 degrees gets no benefit from the sun.
And no shadows. The strap of a mask casts a shadow that gets NO benefit of the sun, so it is as strong as ever. No overhead clouds. No window in the way
The underside of the mask would seem to get no benefit.
RE: Some backing for high temps, humidity, and sunlight as the enemy of the virus - Farm93 - 05-14-2020
I believe the heat, light and disinfectant story at a White House press briefing was largely lost when President Trump then suggested the doctors and scientists could look into injecting things directly into the body.
Given the research I would rather be spending a summer day outside in an urban community pool than a night inside at movie theater with A/C. The forecasts the Fed and the states are using generally anticipate a rather significant decline in cases and death by mid-June with almost no new deaths in July or August. The warm weather, sunny day scenario is what gets us to the projections of ~150,000 deaths by early August.
And all could be fine if everyone on the planet lived in the Northern Hemisphere and worked outside. However, a lot of people in our industrialized society spend large portions of their life indoors, and those in the Southern Hemisphere can always bring the virus back to us in September and October as they end their winter months.
I HOPE the USA spends the summer working diligently to build PPE supplies, assemble test kits and train tracing teams. My fear is that if cases drop in August our government will declare victory and then will not prepare the supply chain or citizens for a surge in October and November cases.